ECOLOGY AND CONSERVATION OF NEOTROPICAL-NEARCTIC MIGRATORY DISSERTATION Presented in Partial...

ECOLOGY AND CONSERVATION OF NEOTROPICAL-NEARCTIC MIGRATORY

BIRDS AND MIXED-SPECIES FLOCKS IN THE ANDES

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the

Degree Doctor of Philosophy in the Graduate

School of The Ohio State University

By

Gabriel J. Colorado, M.S.

Environmental and Natural Resources Graduate Program

The Ohio State University

2011

Dissertation Committee:

Professor Amanda D. Rodewald, Adviser

Professor Elizabeth Marschall

Professor Paul Rodewald

Copyright by

Gabriel J. Colorado

2011

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ABSTRACT

The tropical Andes are widely recognized as one of the world´s great centers of

biodiversity. High levels of both species richness and endemism coupled with one of the

greatest rates of deforestation among tropical forests have made the Andes a major focal

point of international conservation concern. In the face of current and projected rates of

deforestation and habitat degradation of Andean forests, persistent large gaps in our

understanding of ecological responses to anthropogenic disturbances limit our ability to

effectively conserve biodiversity in the region. My dissertation focused on ecology and

conservation of two poorly known components of Andean forest bird communities,

mixed-species flocks and overwintering Neotropical-Nearctic migratory birds.

Specifically, I (1) examined assembly patterns of mixed-species avian flocks, (2)

evaluated the sensitivity of mixed-species flocks and Neotropical-Nearctic migratory

birds to deforestation and structural changes in habitat, and (3) identified potential

physiological consequences of both using shade coffee and flocking to wintering

Neotropical-Neartic migratory birds.

To achieve this, I evaluated richness and abundance patterns of the community of

wintering Neotropical-Nearctic migratory birds and resident mixed-species flocks across

a broad geographical area (approximately 200,000 km2) of Northern and Central Andes,

ranging from northwestern Venezuela in the Mérida Cordillera (± 10 o S, 70 o W) to

northern Peru’s Cóndor Cordillera (± 5 o S, 78 o W), and including the Eastern, Central

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and Western Colombian Cordilleras. From October-March 2007-2010, I surveyed bird

communities and measured habitat characteristics within 84 study sites representing a

range of altitudes, from tropical lowlands at 400 m to low-montane tropical forest at

2,600 m. I examined patterns of non-randomness in Andean mixed-species flocks using

three assembly models: (a) co-occurrence patterns (b) guild proportionality and (c)

constant body-size ratios applied to data on 221 species of resident and Neotropical

migrant birds participating in 311 mixed-species flocks in Venezuela, Colombia,

Ecuador, and Peru. By applying null model analysis to regional presence-absence

matrices of flocking species, I found evidence of assembly patterns for mixed-species

flocks in the Andes suggesting that competitive interactions at both interspecific and

inter-guild levels played important roles in structuring flock social systems in the Andes.

Flock structure seemed less related to morphological (i.e., body size ratios) than to

behavioral attributes, such as foraging behavior, as evidenced by the fact that foraging

guilds (i.e., insectivore, omnivore, nectivore, frugivore) remained relatively proportional

across flocks.

To examine sensitivity of montane forest birds to environmental heterogeneity, I

used an information-theoretic approach to study the association of landscape-scale (i.e.

percentage of forest cover in 1-km2 pixels) and micro-habitat level (i.e. habitat

complexity) on richness and abundance patterns of Neotropical migrants and mixed-

species flocks. I conducted systematic avian surveys within five broadly-defined habitat

types (shade coffee, pastures with isolated trees, successional, secondary forest and

mature forest) at 84 sites distributed from Colombia to Peru based on a stratified-random

design. Distance-based line transect surveys (n = 3 per site) were used to quantify

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patterns of species richness and abundance of Neotropical migrants and mixed-species

flocks. I found that patterns in flock and migrant attributes were well explained by

environmental heterogeneity at multiple spatial scales, though habitat-specific

associations depended upon landscape context. The strength of the association between

regional forest cover and Neotropical migrants was habitat-dependent, and forest cover

was most strongly positively related to flocks within shade coffee. Increasing levels of

habitat complexity had mixed relationships with flock attributes. Whereas complexity

was positively associated with abundance and diversity in successional and silvopastoral

habitats, the opposite pattern was true in shade coffee and secondary forests. Overall, this

research showed that (a) Neotropical migrants and mixed-species flocks were influenced

by environmental factors operating across multiple spatial scales, (b) the importance of

particular environmental attributes changed with landscape context and habitat type, and

(c) intensively managed habitats with overstory trees contributed to avian conservation

by supporting both Neotropical migratory birds and mixed-species flocks.

In my final chapter, I explored the suitability of shaded monocultures for

overwintering Neotropical-Nearctic migratory birds by examining body condition

changes. Because Neotropical-Nearctic migrants frequently join mixed-species flocks

during the nonbreeding season, I also evaluated the extent to which body condition

changed with flocking behavior. I mist-netted 8 species of Neotropical-Nearctic migrants

in shade coffee farms in the Colombian Andes in October-April 2008-2009 and 2009-

2010 and identified individuals as either solitary foragers or flock members. Several

common migratory species, including Cerulean Warbler, Blackburnian Warbler and

Tennessee Warbler, improved their body condition over the course of each day and

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throughout the nonbreeding season. However, neither body condition nor seasonal

change in body condition differed between flocking and solitary individuals for most of

the migratory species evaluated. Cerulean and Blackburnian Warblers showed stronger

improvements in condition when foraging solitary than in flocks. Because birds improved

condition in shade coffee, results also provided additional evidence that agroforestry

systems can provide suitable overwinter habitat to several common Neotropical migrants,

including species of conservation concern such as Cerulean Warbler.

Overall, my dissertation demonstrates that mixed-species flocks and Neotropical

migratory birds are widespread and common components of montane forest avifauna

throughout the tropical Andes. Patterns of community assembly suggest that flocks are

not random associations of species, but rather are structured at least partly in response to

competitive pressures. However, the demonstrated sensitivity of flocks and migratory

birds to landscape and local habitat changes suggests that continued patterns and rates of

land cover change might disrupt the unique social system of mixed-species flocks as well

as suitability of Andean forests for overwintering migratory birds. Fortunately, my

research provides evidence that certain management systems, such as shade coffee and

silvopasture, have the potential to support abundant and diverse migrants and flocks.

Regional conservation efforts should further explore how agroforestry systems can be

used to meet both ecological and social needs in human-dominated landscapes of the

Andes.

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DEDICATION

A Luciana. Eres el ser más hermoso que he visto en mi vida. Tu existencia cambió la mía,

y llena mi corazón.

A Yira. Pudiste haber llegado antes o pudiste haber llegado después, pero llegaste en el

momento indicado.

A Robinson. Lo siento mucho por mi incapacidad de haber hecho lo correcto. Estás

siempre ahí.

A Alberto. He pasado mucho tiempo tratando de encontrarte. Lo curioso, siempre estás

ahí, en mi personalidad, en mis acciones y en mi forma de pensar.

A Gloria. El tiempo no nos ayudó, pero te recuerdo tan fuerte como puedo.

A Carlos. Me alegra que estés de regreso. Te extrañé mucho.

A Eugenia. Todas mis acciones tienen una parte de ti, y soy la continuación de tus

pensamientos y deseos. Tu amor por la naturaleza está inevitablemente en mí.

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ACKNOWLEDGMENTS

I would like to express my gratitude to my advisor, Amanda D. Rodewald, for her

continued support and orientation during the process of this research. We had really

productive and enlightening conversations, here in the United States and in many other

places. I appreciate her optimism and enthusiasm as well as her interest for ecology and

conservation. Thanks for being so patient with me, in particular with my writing in a

foreign language. I would like to thank Professors Elizabeth Marschall and Paul

Rodewald for serving as members of my committee and for their invaluable suggestions

and comments throughout my study. I also would like to thank my colleagues from the

Terrestrial Wildlife Ecology Lab for advice, support and, particularly, enjoyable “happy”

hours. My study would not have been a reality without the funding support by USDA

Forest Service International Programs, National Council for Air and Stream

Improvement, National Fish and Wildlife Foundation, The Nature Conservancy, The

Corporación Autónoma Regional del Centro de Antioquia and The School of

Environment and Natural Resources from The Ohio State University. Special

acknowledgment to incredible field crews, who constantly demonstrated that the

impossible was possible and that we could beat the maldición cerulea: in Venezuela, I am

grateful with J. Miranda, D. muñoz, C. Tosta and C. Valeris; in Colombia, I am grateful

to E. Agudelo, C. Alcázar, H. Arias, F. Ayerbe, J. Botero, G. Buitrago, S. David, J. Díaz,

C. Estrada, A. Fernandez, P. Florez, S. Galeano, C. Gomez, A. Gonzalez, L. Gomez, A.

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Henao, E. Lara, C. Londoño, L. Londoño, J. López, L. Rubio, M. Martínez, C. Mazo, E.

Munera, J. Muñoz, D. Ocampo, A. Pizarro, P. Pulgarín, Y. Sanabria, Y. Sepulveda, G.

Suarez, and M. Sepulveda; in Ecuador, to Esteban Guevara and his crew from Aves &

Conservacion; in Peru, to Wily Palomino from ECOAN, Gerardo Medina from the

Rainforest Alliance, the Santos brothers and to Pablo Bazan-Jempekit; finally, from

United States, Ian Ausprey, Jay Carlisle and Felicity Newell. Thank you all for the hard

work, and for being part of such a challenging project. Without your effort and positive

attitude, this could not have been done. I also would like to thank Paul Hamel, D.

Mehlman and Carol Lively. Thank you for inviting me to be part of El Grupo Ceruleo,

and for trusting me to carry out this unforgettable adventure. I enjoyed our long

conversations and your sincere interest in conservation. I would like to thank my family,

Eugenia, Carlos and Luciana. Thanks for their love and for being so supportive and for

staying there, no matter what. Thanks for accepting me the way I am, and for accepting

that I was not there to be a good son, a good brother and a good uncle. I finally want to

thank Yira Sepulveda for understanding me and being there for me with her

unconditional affection.

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VITA

2008–present……………Graduate Associate, School of Environment and Natural

Resources, The Ohio State University

2003-present…………….Field Coordinator, Cerulean Warbler Research in wintering

grounds.

2006……………………..M.S. Forests and Environmental Conservation, Universidad Nacional de Colombia, Medellín, Colombia.

2003……………………. B.S. Forestry Engineering, Universidad Nacional de Colombia,

Medellín, Colombia.

2003……………………..Biological Technician, Idaho Bird Observatory, ID.

1999……………………..Intern, Hawk Mountain Sanctuary, PA.

PUBLICATIONS

Colorado G. 2010. Fall migration of Empidonax Flycatchers in Northwestern Colombia. Journal of Field Ornithology 81(3):259–266.

Colorado G., Hamel P., Rodewald A. and W. Thogmartin. 2008. El grupo cerúleo: collaboration to assess nonbreeding range of cerulean warbler in south America. Ornitologia Neotropical (suppl.) 19: 521-529.

Barker, S., Benítez, S., Baldy, J., Cisneros Heredia, D., Colorado Zuluaga, G., Cuesta, F., Davidson, I., Díaz, D., Ganzenmueller, A., García, S., Girvan, M. K., Guevara, E., Hamel, P., Hennessey, A. B., Hernández, O. L., Herzog, S., Mehlman, D., Moreno, M. I., Ozdenerol, E., Ramoni-Perazzi, P., Romero, M., Romo, D., Salaman, P., Santander, T., Tovar, C., Welton, M., Will, T., Pedraza, C., Galindo, G. 2007. Modeling the South American Range of Cerulean Warbler. ESRI conference paper. http://gis.esri.com/library/userconf/proc06/papers/pap_1656.pdf

Sierra C.A., del Valle J.I., Orrego S.A., Moreno F.H., Harmon M.E., Zapata M., Colorado G.J., Herrera M.A., Lara W., Restrepo D.E., Berrouet L.M., Loaiza L.M. and Benjumea J.F.2007. Total carbon stocks in a tropical forest landscape of the Porce region, Colombia. Forest Ecology and Management, 243 (2-3):299-309.

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FIELDS OF STUDY

Major Field: Natural Resources

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TABLE OF CONTENTS

ABSTRACT……………………………………………………………………………....ii

DEDICATION…………………………………………………………………................vi

ACKNOWLEDGMENTS……………………………………………………………….vii

VITA………………………………………………………………...................................ix

LIST OF TABLES………………………………………………………………….......xiii

LIST OF FIGURES……………………………………………………………………xviii

1 INTRODUCTION…………………………………………………………………......1

Objectives and Chapter Overview………………………………………………... 4

2 ASSEMBLY PATTERNS OF MIXED-SPECIES AVIAN FLOCKS IN THE ANDES ……………………………………………………………………................................6

Introduction………………………………………………………………….......... 7

Study area and methods…………………………………………………………. 11

Results…………………………………………………………………................ 17

Discussion………………………………………………………………….......... 20

Literature Cited………………………………………………………………….. 24

3 MULTISCALE INFLUENCE OF DEFORESTATION AND HABITAT ALTERATION ON NEOTROPICAL-NEARCTIC MIGRATORY BIRDS AND MIXED-SPECIES FLOCKS IN THE ANDES…………………………………………. 45

Introduction…………………………………………………………………........ 46

Study area and methods…………………………………………………………. 49

Results…………………………………………………………………................ 57

Discussion………………………………………………………………….......... 62

Literature cited…………………………………………………………………... 71

4 PATTERNS OF MASS CHANGE IN WINTERING NEOTROPICAL-NEARCTIC MIGRATORY BIRDS IN SHADED MONOCULTURES IN THE ANDES………… 115

Introduction…………………………………………………………………...... 116

Study area and methods………………………………………………………... 118

Results………………………………………………………………….............. 123

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Discussion…………………………………………………………………........ 125

Literature cited…………………………………………………………………. 131

5 BIBLIOGRAPHY………………………………………………………...………... 156

APPENDICES…………………………………………………………………............. 189

Appendix A. Field design for Neotropical-Nearctic migratory birds and mixed-species flocks surveys in the Northern and Central Andes…………………….. 189

Appendix B. Presence-absence matrix built from the species pool of flocking species in the locality of Aguachica, Eastern Andes, Colombia………………..191

Appendix C. Percentage of species per guild in 311 mixed-species bird flocks recorded in 13 regions in the Andes. 2007-2010………………………………. 194

Appendix D. Bird species and families recorded in 311 mixed-species flocks in the Andes, 2007-2010………………………………………………………….. 207

Appendix E. Characteristics of 84 1-km2 pixels surveyed in 11 different regions in the Andes in Colombia, Ecuador and Peru. Wintering seasons 2007-2010….... 218

Appendix F. Neotropical-Nearctic migratory birds and mixed-species flocks attributes recorded in 1-km2 pixels (84 and 39 pixels, respectively) in 11 different regions in the Andes in Colombia, Ecuador and Peru. Wintering seasons 2007-2010……………………………………………………………………………..225

Appendix G. Coefficients of top-ranked regression models relating flock richness and abundance attributes and environmental variables in the Andes. Statistics include model estimates, the standard errors (SE) and t-statistic. Analysis based on 39 1-km2 pixels……………………………………………………………... 232

Appendix H. Coefficients of top-ranked regression models (ΔAICc < 2) relating Neotropical migrant attributes and environmental variables in the Andes. Statistics include model estimates, the standard errors (SE), t for estimate and P value……………………………………………………………………………. 238

Appendix I. Occurrence of Neotropical-Nearctic migrant land birds in 84 1-km2 pixels surveyed in 11 different regions in the Andes in Colombia, Ecuador and Peru. Wintering seasons 2007-2010………………………………………….... 240

Appendix J. Relationship of body condition and sex, age, body molt and season for Neotropical-Nearctic migratory bird species in shaded monocultures in Southwestern Antioquia department, Colombia, 2008-2010. *P < 0.05 and **P < 0.01……………………………………………………………………………...246

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LIST OF TABLES

Table 2.1. Site characteristics for 12 different regions on the Colombian, Ecuadorian and

Peruvian Andes where mixed-species flocks were recorded,October-March, 2007-2010.

Values are mean ± SD. ...................................................................................................... 34

Table 2.2. Mean number of species and individuals recorded in 311 flocks in 12 regions

in the Northern and Central Andes, October-March, 2007-2010. Values are mean ± SD.

........................................................................................................................................... 35

Table 2.3. Number of bird species per family found in 311 mixed-species flocks recorded

in the Northern and Central Andes, October-March, 2007-2010. .................................... 36

Table 2.3 (continued) ........................................................................................................ 37

Table 2.4. Percentage of most common bird species assisting mixed-species flocks in the

Northern and Central Andes. Species present in 10% or more of flocks are listed. Mean

abundance calculated for those flocks with the species present. Asterisk denotes

Neotropical-Nearctic migratory birds. .............................................................................. 38

Table 2.4 (continued) ........................................................................................................ 39

Table 2.5. Result of three co-occurrence indices, C-score, number of species

combinations and checkerboard pairs, and the null model analysis for 11 sites in the

Andes. Expected score generated using the Knight’s Tour Algorithm. Fixed-fixed null

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model (SIM9 in Gotelli 2000). P < 0.05*, P < 0.01**. Two localities, Chicamocha and

Tolima, were excluded due to small sample size (< 3 flocks). ......................................... 40

Table 2.6. Number of flocks that showed significant differences (P < 0.05) in the

minimum size ratios and the variance of size ratios when compared with randomly

generated flocks. After conducting the binomial test for greater minimum size ratios and

less variance of size ratios, no significant differences were found. Two localities,

Chicamocha and Tolima, were excluded due to small sample size (< 3 flocks). ............. 41

Table 3.1. Site characteristics for 11 different landscapes on the Colombian, Ecuadorian

and Peruvian Andes. Values presented are mean ± SD. ................................................... 84

Table 3.2. Pearson’s correlations for 6 structural variables derived from 487 vegetation

plots in 11 regions in the Andes. *P < 0.05; **P < 0.01. .................................................. 85

Table 3.3. Set of candidate models to test for relationships between flocks and migrants

attributes and environmental effects. K represents number of parameters to be estimated.

........................................................................................................................................... 86

Table 3.4.Correlation of habitat variables with derived Principal Components Analysis

scores, eigenvalue and cumulative variance explained in 11 regions in the Northern and

Central Andes. *P < 0.05; **P < 0.01. ............................................................................. 87

Table 3.5. Fifteen most common bird species in 186 mixed-species flocks in the Andes.

The metric represents the percentage of flocks that included the listed species. .............. 88

Table 3.6. Summary statistics for MRPP results of comparisons of average within-group

distance of mixed-species flocks across five different habitats in the Andes. T represents

the test statistic describing the separation between habitats (the more negative, the

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stronger the separation); P represents the probability of the expected delta (the weighted

mean within-group distance) calculated for all possible partitions of the data being as

small or smaller than the observed delta; and A represents the chance-corrected within

group agreement describing the within-group homogeneity as compared to random

expectation (e.g. A = 0 when heterogeneity within groups equals expectation by chance;

MacCune and Grace 2002). .............................................................................................. 89

Table 3.7. Regression models to relate flock attributes and environmental variables.

Model selection was based on biased-adjusted Akaike’s Information Criterion (AICc).

Statistics include the number of estimated parameters (K), the second-order Akaike

Information Criterion (AICc), AIC differences (ΔAICc), and Akaike weights (wi).

Models are listed in descending order of wi. Models with ΔAICc < 2 are listed.............. 90

Table 3.8. Regression models relating environmental variables and richness and

abundance of Neotropical migrants detected on transects. Model selection was based on

biased-adjusted Akaike’s Information Criterion (AICc). Statistics include the number of

estimated parameters (K), the second-order Akaike information Criterion (AICc), AIC

differences (ΔAICc), and Akaike weights (wi). Models are listed in descending order of

wi. Only models with ΔAICc < 2 are listed. ..................................................................... 91

Table 3.9. Summary of main relationships of forest cover and habitat complexity on

flocks and Neotropical migrant attributes in different habitat types. ................................ 92

Table 4.1. First captured individuals and mean weight of 8 Neotropical migratory species

in shaded monocultures over two winter seasons in southwestern Antioquia, Colombia,

2008-2010. Values are mean ± standard deviation. ........................................................ 143

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Table 4.2. Body condition for Neotropical-Neartic migratory birds captured in flocks and

solitary in shaded monocultures in southwestern Antioquia Department, Colombia, 2008-

2010. Values are mean ± SE. Values in parenthesis are sample sizes. ........................... 144

Table 4.3. Result of ANOVA test for differences in body frame (PC1) between

Neotropical-Nearctic migratory birds captured in flocks and solitary in shaded

monocultures in southwestern Antioquia department, Colombia, 2008-2010. Values are

mean ± SE. Values in parenthesis are sample sizes. ....................................................... 145

Table 4.4. Regression models to relate body condition and (1) time of day and (2) day of

season for Neotropical-Neartic migratory bird species in shaded monocultures in

southwestern Antioquia department, Colombia, 2008-2010. ......................................... 146

Table 4.5. Coefficients (± SE) of regression models to evaluate the relationship between

daily changes in body condition and flocking behavior in Neotropical-Neartic migratory

birds in shaded monocultures in Southwestern Antioquia department, Colombia. 2008-

2010. Interaction term represents status x Time of day. P < 0.01*, P < 0.05**, 0.05 < P <

0.1***.............................................................................................................................. 147

Table 4.6. Mean body condition for eight Neotropical-Nearctic migratory bird species in

relation to their social status, segregated by sex, age and season in shaded monocultures

in southwestern Antioquia department, Colombia, 2008-2010. Values are mean ± SD.

Sample size in parenthesis. * P < 0.05. .......................................................................... 148

Table 4.7. Coefficients (± SE) of regression models to evaluate the relationship between

seasonal changes in body condition and flocking behavior in Neotropical-Neartic

migratory birds in shaded monocultures in Southwestern Antioquia department,

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Colombia. Interaction term represents status x Day of season. P < 0.01*, P < 0.05**, 0.05

< P < 0.1***. ***. Empidonax Flycatchers were excluded from this analysis for lack of

individuals caught in flocks later in the season. ............................................................. 149

Table 4.8.F-test for comparison of standard deviations of body condition between flock

and solitary individuals for Neotropical-Nearctic migratory birds in shaded monocultures

in Southwestern Antioquia department, Colombia. ........................................................ 150

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LIST OF FIGURES

Figure 2.1.Relative proportion of flocking species in Andean flocks represented by each

foraging guild. Lines were constructed by regressing relative abundance vs. log flock size

(following Feeley 2003; for an example, see Appendix C). a. Carache; b. Aguachica; c.

San Jose de la Montana; d. Yariguies. .............................................................................. 42

Figure 2.1.(Continued). e. Abejorral; f. Paya; g. Cauca; h. Sangay National Park. ......... 43

Figure 2.1.(Continued). i. Cajamarca; j. Pacora; k. Southwestern Antioquia; l. All

localities together. ............................................................................................................. 44

Figure 3.1. Five habitat types identified during surveys in the Andes. From the top left to

the bottom, clockwise: mature forest, secondary forest, shade coffee, pastures with

isolated trees and successional. ......................................................................................... 93

Figure 3.2. Eleven surveyed locations in the Northern and Central Andes. Numbers

represent 1-km2 pixel sites visited within each region. From north to south: Aguachica,

San José de la Montaña, Yariguies, Chicamocha, Abejorral, Paya, Ibague, Rosas, Patia,

Sangay National Park and Chingozales. ........................................................................... 94

Figure 3.3. Example of field sampling design for allocating 100 m line transects within 1-

km2 pixels to survey bird fauna and to locate temporary vegetation plots in the Andes. . 95

Figure 3.4. Ordination of habitat features for 11 regions in the Northern and Central

Andes based on habitat factors. Data labels refer to percentage of forest cover per region.

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PC1 reflected increasing habitat complexity (e.g., density of woody plants, canopy height

and cover, basal area, ground cover), and PC2 was positively correlated with percentage

of ground cover. ................................................................................................................ 96

Figure 3.5. Percent forest cover within 1-km2 pixels differed among five habitat types in

the Andes, 2007-2010. Different letters indicate significant differences among habitats

using α = 0.05. ................................................................................................................. 97

Figure 3.6. Relationship between structural complexity of the habitat and percentage of

forest cover obtained for 84 1-km2 pixels in the Andes. ................................................... 98

Figure 3.7. Species richness of Neotropical-Nearctic migrants increased with flock

richness and flock encounter rate (i.e. Number of flocks encountered per hour of survey).

Lineal models were constructed accounting for flock size. .............................................. 99

Figure 3.8. Geographic distribution of Neotropical-Nearctic migrants in the Andes along

elevation and latitude gradients. ..................................................................................... 100

Figure 3.9. Sample-based smoothed accumulation curves of species in mixed-species

flocks among five habitats. Arrow indicates maximum rarefaction point in the number of

individuals achieved for all the habitats. ......................................................................... 102

Figure 3.10. Sample-based smoothed accumulation curves of Neotropical-Nearctic

migrant species assisting mixed-species flocks among five habitats. Arrow indicates

maximum rarefaction point in the number of individuals achieved for all the habitats. 103

Figure 3.11. NMS ordination joint plot of sample scores (i.e. mixed-species flocks) in

species space on the first and third NMS axes for the two most contrasting habitats, shade

coffee (open circles) and mature forest (crosses). .......................................................... 104

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Figure 3.12. Relationship between flock species richness and increasing percentage of

forest cover within 1-km2 pixels in the Andes, 2007-2010. Graphs constructed using top-

ranked models simulating a gradient of forest cover. Dotted lines along major line

represent standard errors for the predictions. .................................................................. 105

Figure 3.13. Relationship between flock size and increasing percentage of forest cover

within 1-km2 pixels in the Andes, 2007-2010. Graphs constructed using top-ranked

models simulating a gradient of forest cover. Dotted lines along major line represent

standard errors for the predictions. ................................................................................. 106

Figure 3.14. Relationship between flock encounter rate per hour and increasing

percentage of forest cover within 1-km2 pixels in the Andes, 2007-2010. Graphs

constructed using top-ranked models simulating a gradient of forest cover. Dotted lines

along major line represent standard errors for the predictions. ...................................... 107

Figure 3.15. Relationship between richness of flocks and habitat structure in the Andes,

2007-2010. Graphs constructed using top-ranked models simulating a gradient of habitat

complexity. Dotted lines along major line represent SE for the predictions. Gray line:

high regional forest cover (61.9%). Blue line: low regional forest cover (19.6%). ........ 108

Figure 3.16. Relationship between flock size and habitat structure in the Andes, 2007-

2010. Graphs constructed using top-ranked models simulating a gradient of habitat



Figure 3.17. Relationship between flock encounter rate per hour and habitat structure in

the Andes, 2007-2010. Graphs constructed using top-ranked models simulating a gradient

xxi

of habitat complexity. Dotted lines along major line represent standard errors for the

predictions. Dotted lines along major line represent SE for the predictions. Gray line:


Figure 3.18. Association between richness of Neotropical migrant birds recorded on

distance-based line transects and percentage of forest cover within 1-km2 pixels in the

Andes. Graphs constructed using top-ranked models simulating a gradient of forest cover.

Dotted lines along major line represent standard errors for the predictions. .................. 111

Figure 3.19. Association between abundance of Neotropical migrant birds recorded on



Dotted lines along major line represent standard errors for the predictions ................... 112

Figure 3.20. Association between richness of Neotropical migrant birds and local habitat

structure in the Andes. Graphs constructed using top-ranked models simulating a gradient

of habitat structure. Dotted lines along major line represent standard errors for the



Figure 3.21. Association between abundance of Neotropical migrant birds and local

habitat structure in the Andes. Graphs constructed using top-ranked models simulating a

gradient of habitat structure. Dotted lines along major line represent standard errors for

the predictions. Dotted lines along major line represent SE for the predictions. . Gray

line: high regional forest cover (63.8%). Blue line: low regional forest cover (17.8%). 114

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Figure 4.1.Banding stations in Southwestern Antioquia department, Colombia. 1.

Gualanday farm, Fredonia Municipality, 2. Cultivares farm, Jerico Municipality and 3. La

Cumbre farm, Tamesis Municipality. Source: msn Encarta. .......................................... 151

Figure 4.2.Relationship between daily body condition and social status in Neotropical

migratory bird species in shaded monocultures in Antioquia department, Colombia. Open

circle with solid line: birds in flocks. Closed circle with dotted line: solitary birds. ...... 152

Figure 4.3.Relationship between seasonal body condition and social status in Neotropical

migratory bird species in shaded monocultures in Antioquia department, Colombia. Open

circle with solid line: birds in flocks. Closed circle with dotted line: solitary birds. ...... 154

1

1 INTRODUCTION

Spanning nearly 9000 km of land over tremendous altitudinal and climatic diversity

(Jørgensen 2009), the Andes Mountains are considered one of the most diverse places in

the world with impressively high levels of endemism (Gentry 1986, Henderson et al.

1991, Jørgensen 2009). Unfortunately, deforestation and the accompanying loss of

biodiversity are rampant in the Andes (Skole & Tucker 1993, Bierregaard & Stouffer

1997, Orejuela 2000). Over 90% of the Northern Andes, for example, have been

deforested or highly altered by human activity (Henderson et al. 1991). Major causes of

deforestation include establishment of agriculture and silvopastoral systems, urbanization

and selective logging, among others (Henderson et al. 1991). Collectively, these

anthropogenic changes have made Andean forests among the most endangered

ecosystems in the world (Cavelier 1997).

The negative effects of forest loss and degradation are not only experienced by the

resident biota, but also by a wide range of transient populations of species that rely on

tropical montane forests during the nonbreeding season. Neotropical-Nearctic migratory

birds are one such example of a group that depends upon Andean habitats. Of the

approximately 650 Nearctic-Neotropical migratory birds, more than 200 species occur in

the Northern and Central Andes (Rappole 1995). In contrast to our knowledge of factors

limiting Neotropical migrants on breeding grounds (e.g. increased predation, parasitism,

shortage of suitable breeding habitat; Brittingham & Temple 1983, Wilcove 1985,

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Robbins et al. 1989), remarkably little is known of their ecology, distribution, and habitat

needs in the wintering grounds (e.g. Petit et al. 1995, Rotenberry et al. 1995, Marra et al.

1998, Marra & Holmes 2001, Newton 2004, Norris et al. 2004). This lack of knowledge

is particularly surprising given that most Neotropical-Nearctic migrants spend one-half to

two-thirds of their life cycle in Neotropical ecosystems. The rapid human-induced

changes in habitat throughout much of the Neotropics are widely believed to contribute to

population declines of numerous Neotropical migratory birds (Robbins et al. 1989,

Terborgh 1989, Rappole 1995), typically associated with conversion from high to low

quality habitats (Wunderle & Latta 1996, Marra & Holmes 2001, Brown et al. 2002,

Carlo et al. 2004, Johnson et al. 2006) and food availability (Strong & Sherry 2000,

Johnson & Sherry 2001). In contrast, others have reported greater abundance of

Neotropical migrants in early successional and edge habitats, and underrepresentation in

undisturbed moist forests (Orejuela et al. 1980, Pearson 1980, Robinson et al. 1988, Petit

et al. 1995). Moreover, while several studies have documented that resident bird species

are affected by both the amount of forest available within a landscape (e.g. Saab 1999,

Drapeau et al. 2000, Lee et al. 2002) and the nature of the landscape matrix (e.g.

Saunders et al. 1991, Sisk et al. 1997, Fahrig 2001, Renjifo 2001, Ricketts 2001,

Hersperger & Forman 2003, Dunford 2004), little is known about how Neotropical

migrants respond to local- and landscape-scale environmental variation in their wintering

grounds. Studies of the relative effects of deforestation and associated fragmentation on

migratory birds are still urgently needed (Petit et al. 1993).

Matching the paucity of information on wintering ecology of Neotropical migrants in

the Andes is our limited understanding of the response of social systems of birds (i.e.

3

mixed-species flocks) to deforestation and habitat alteration. Several studies have

indicated that mixed-species flocks are negatively affected by fragmentation and habitat

disturbance (e.g. Harper 1989, Stouffer & Bierregaard 1995, Maldonado-Coelho &

Marini 2004, Sodhi et al. 2004, Kumar & O’Donnell 2007). These alterations alter habitat

structure and microclimate in ways that can reduce food availability and predictability

(Bierregaard & Lovejoy 1989, Stratford & Stouffer 1999, Maldonado-Coelho & Marini

2000, 2004, Tellería et al. 2001), and ultimately affect the occurrence and abundance of

flocking species, as well as their propensity to flock (Stouffer & Bierregaard 1995,

Thiollay 1999, Maldonado-Coehlo & Marini 2000, Van Houtan et al. 2006). Despite

consistency with which negative responses of flocks to forest fragmentation and

degradation have been documented (Stouffer & Bierregaard 1995, Maldonado-Coehlo &

Marini 2000, Lee et al. 2005), flocks also have displayed some level of habitat flexibility

(e.g. Murcia 1995, Dale et al. 2000, Renjifo 2001). For example, in experimentally-

created fragments in Manaus (Brazil), mixed-species flocking species that used forest

edges and secondary forests survived, meanwhile those species restricted to the forest

interior locally disappeared (Stouffer & Bierregaard 1995). Moreover, the variation of

mixed-species flock attributes within disturbed and undisturbed habitats is apparently still

unclear. One illustration is the apparent absence of mixed species flocks in shade coffee

in Hispaniola, despite being common in forests on the island (Latta & Wunderle 1996). In

contrast, mixed-species flocks were more common in shaded coffee than in natural forest

in Panama (Pomara et al. 2003), though such patterns can arise from mechanisms acting

at different scales (e.g. Cleary et al. 2005). Knowledge of the relative importance of

different landscape elements on mixed-species flocks is crucial given that many bird

4

species, including Neotropical migrants, spend a large proportion of time with flocks

(Munn & Terborgh 1979, Latta & Wunderle 1996, Maldonado-Coelho & Marini 2004,

Lee et al. 2005, Sridhar & Sankar 2008).

Objectives and Chapter Overview

The objectives of my dissertation were to (1) examine assembly patterns of mixed-

species avian flocks, (2) evaluate the sensitivity of mixed-species flocks and Neotropical-

Neartic migratory birds to deforestation and habitat structural changes, and (3) identify

potential physiological consequences of using shade coffee and flocking to wintering

Neotropical-Neartic migratory birds.. To do this, I studied Neotropical-Nearctic

migratory birds and mixed-species flocks in montane forest habitats across the Northern

and Central Andes in Venezuela, Colombia, Ecuador and Peru between 2007-2010.

In chapter 2, I assessed patterns of non-randomness in Andean mixed-species flocks

using three complementary assembly models framed on the community assembly theory.

I demonstrated that Andean mixed-species flocks displayed structuring patterns at both

interspecific and inter-guild levels associated with deterministic competitive processes. In

contrast, I found weak evidence for a morphological segregation of avian species within

flocks, and some groups of birds may actually show aggregation in sizes.

In chapter 3, I evaluated the association of landscape-scale (i.e. percentage of forest

cover) and micro-habitat level (i.e. habitat complexity) changes with richness and

abundance patterns of Neotropical migrants and mixed-species flocks within five

broadly-defined habitat types. I found that patterns in flock and migrant attributes were

well explained by environmental heterogeneity at multiple spatial scales, though habitat-

5

specific associations depended upon the landscape context. I also provided empirical

evidence that changes in landscape forest cover (e.g. deforestation) contributed to the

spatial variation in Andean bird communities.

In chapter 4, I assessed diurnal and seasonal changes in body condition of

Neotropical-Nearctic migratory birds wintering in shaded monocultures and evaluated if

the patterns were related to flocking behavior. Neither body condition nor seasonal

change in body condition differed between flocking and solitary individuals for most of

the migratory species evaluated. However, Cerulean and Blackburnian Warblers showed

stronger improvements in condition when foraging solitary than in flocks. My results also

provided evidence that several common Neotropical migrants, including species of

conservation concern such as Cerulean Warbler, improved their body condition in shade

coffee farms, highlighting the relevance of this agroforestry system.

Overall, my research shows that mixed-species flocks and Neotropical migratory birds

are widespread and common components of montane forest avifauna throughout the

tropical Andes. Because these avian communities have complex structure (i.e., they are

not random assemblages) and are sensitive to landscape and local habitat changes, my

work cautions that continued land cover change has the potential to disrupt the unique

social system of mixed-species flocks as well as suitability of Andean forests for

overwintering migratory birds. Fortunately, certain management systems, such as shade

coffee and silvopasture, can support abundant and diverse migrants and flocks. Thus,

conservation efforts should explore how agroforestry systems can be used to meet both

ecological and social needs in human-dominated landscapes of the Andes.

6

2 ASSEMBLY PATTERNS OF MIXED-SPECIES AVIAN FLOCKS IN THE

ANDES

Abstract. Whether biotic communities are structured by deterministic or stochastic

processes is a central issue in community ecology. Several studies have shown patterns of

species segregation that are consistent with the hypothesis that competition and niche-

partitioning structure species assemblages in animal communities. However, the

theoretical framework has been seldom applied to social aggregations of species within

communities. I assessed patterns of non-randomness in Andean mixed-species flocks

using three assembly models: (a) co-occurrence patterns (b) guild proportionality; and (c)

constant body-size ratios using data from 221 species of resident and Neotropical migrant

birds participating in 311 mixed-species flocks at 12 sites distributed in Venezuela,

Colombia, Ecuador, and Peru. Significant assembly patterns for mixed-species flocks

based on co-occurrence models and guild proportionality models suggest that competitive

interactions at both interspecific and inter-guild levels play an important role in

structuring this social system in the Andes. The proportion of species among foraging

guilds (i.e., insectivore, frugivore, omnivore, nectivore) remained constant but with some

noise across flocks in different regions throughout the study area. In contrast, I found

little evidence that structuring of mixed-species flocks in the Andes was mediated by

constant body-size ratios. Rather, I found greater variance of body-size ratios within

flocks, suggesting that, in general, evidence for a morphological segregation of avian

7

species within flocks was weak and some groups of birds may show aggregation in sizes

within flocks. Overall, my findings indicate that bird flocks assemblages across the

Andes are shaped by negative interspecific interactions indicative of competitive effects.

Key words: mixed-species bird flocks, Andes, community, competition, assembly

rules, co-occurrence, guild proportionality, body-size ratio, null models.

Introduction

Few subjects in community ecology have generated as much attention or evoked as

much debate as the assembly of biotic communities and the role of deterministic and

stochastic processes in structuring local and regional assemblages of species (Clements

1916, MacArthur & Wilson 1967, Strong et al. 1984, Weiher & Keddy 1999, Hubbell

2001, Lortie et al. 2004). Community assembly provides a conceptual framework for

understanding these processes (Chase 2003), and two main tradeoff-based theories of

interspecific competition (niche-assembly theory; Tilman 1988, Algar et al. 2005) and

neutrality (dispersal- or neutral-assembly theory; Bell 2000, Hubbell 2001, Algar et al.

2005, McGill et al. 2006) have been promoted as potential explanations for the assembly,

dynamics and structure of ecological communities (Tilman 2004). The point of deviation

between these two theories is the extent to which species co-occurrence is determined by

stochastic versus deterministic factors (e.g. Hubbell 1979, Hubbell & Foster 1986,

Robinson & Terborgh 1995, Terborgh et al. 1996). Consequently, the two theories make

markedly different predictions about community assembly processes (Reshi et al. 2008).

While the niche tradeoff models predict that species will most strongly inhibit

establishment of species similar to them, neutral models assume that all species are

8

competitively identical and that distribution of species are determined by random forces

driven by demographic stochasticity (Hubbell 2001). Ecologists increasingly recognize

that both deterministic (e.g., competition) and stochastic or neutral (e.g., dispersal

limitation) processes contribute to community assembly (Ricklefs 1987, Svenning et al.

2004, John et al. 2007). The idea that species assemblages are governed more by the

outcome of deterministic competitive processes than by autoecological characteristics has

generated controversy (Connor & Simberloff, 1979, Diamond & Gilpin 1982, Gilpin &

Diamond 1984), but recent studies show patterns of species segregation that are

consistent with the hypothesis that competition and niche-partitioning structure species

assemblages in several living communities (Gotelli & MacCabe 2002).

While co-occurrence patterns and assembly rules (i.e. filters imposed on a regional

species pool that act to determine the local community structure and composition; Keddy

1992) have been studied across a wide range of taxa (e.g. plants: Holdaway & Sparrow

2006, Burns 2007; insects: Cole 1983; reptiles: Pianka 1986; birds: Diamond 1975;

fishes: Bellwood et al. 2002; mammals: Fox 1989, Fox & Kirkland 1992, Fox & Brown

1993, Meyer & Kalko 2008), the theoretical framework has been seldom applied to social

aggregations of species within communities. Structuring patterns of assemblages such as

mixed-species flocks have been almost entirely overlooked, and to my knowledge only

one published study has addressed this subject (Graves & Gotelli 1993). Mixed-species

flocks represent a prevalent and important component of most tropical forests, and

competition is generally thought to be the predominant underlying structuring mechanism

(Graves & Gotelli 1993). Although mixed-species flocks are relatively well studied in

terms of their composition, internal structure and social relationships among flock

9

participants (e.g. Hutto 1994, Develey & Peres 2000, Greenberg 2000, Lee et al. 2005,

Sridhar & Sankar 2008, Sridhar et al. 2009), the assemblage patterns and underlying

processes that drive their structure and organization are poorly understood (Goodale &

Kotagama 2005), particularly within tropical communities that harbor high species

diversity and large number of rare species. Understanding the processes that guide flock

assembly is especially important today, as natural habitats have been extensively

deforested and fragmented.

Mixed-species flocks present a unique opportunity for testing the strength of

deterministic vs. stochastic factors structuring flocks because the ecological similarity of

most participating species makes strong competition likely (Graves & Gotelli 1993). To

my knowledge, the only published research evaluating co-occurrence patterns and the

structure of mixed-species flocks was conducted by Graves and Gotelli (1993), who

studied permanent mixed-species flocks within a local Amazonian avifauna. In this

system, potentially competing pairs of congeneric species with similar ecologies co-

occurred in flocks less often than expected by chance, resulting in perfect checkerboard

distributions. The authors suggested that flocks may be considered analogs to islands (or

fragments) that are colonized by different subsets of species from the local avifauna and

the spatial scale may allow that any individual bird of the species pool could potentially

“colonize” any flock.

I examined patterns of non-randomness assembly in mixed-species flocks of resident

and Neotropical-Nearctic migrant birds in the northern Andes. I examined two specific

questions: (1) Does the presence of a particular flocking species influence the occurrence

of other flocking species? and (2) Do species sharing particular traits (i.e., members of

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the same foraging guild and similar body size) have inhibitory effects on each other? The

coexistence and structuring of species within communities under the ecological niche

theory is primarily based on two assumptions, (1) species with strong overlap in resource

use cannot coexist (Hardin 1960, Simberloff & Connor 1981) and (2) species that coexist

differ in functional morphology or body size allowing them to exploit different resources

(Hutchinson 1959, Simberloff & Boecklen 1981). Thus, to study non-random patterns in

mixed-species flocks following these assumptions, I used species- and trait-based

approaches. I first evaluated three co-occurrence metrics (C-score, number of species

combinations and the variance ratio; Gotelli 2000) to test for assembly patterns in mixed-

species flocks at the species level. To determine if flock composition and species co-

occurrence deviated from that expected for randomly-generated flocks, I used a null

model approach to exclude the biological effects (e.g. competition, mutualism) on the

occurrence of species in flocks, as suggested by Gotelli (2000) and Gotelli & McCabe

(2002). First promoted by Connor & Simberloff (1979), null models (i.e. models that

eliminate the effects of deterministic processes by randomization of observed data; Burns

2007) have been widely used to test hypothesis of assembly rules, especially to compare

random arrangements of species constructed from regional species pools to observed

patterns in species distributions (Zobel et al. 1993, Weiher & Clarke 1998, Anderson et

al. 2000, Gotelli 2000, Peres-Neto et al. 2001).

To evaluate the role of competition in structuring flocks at a higher level of

organization of functional groups (i.e. trait-based approach), I used two models of

assembly patterns, the guild proportionality model (Wilson 1989) and the constant body-

size ratio model (Case et al. 1983, Dayan & Simberloff 1994). Because competitive

11

exclusion is expected to occur primarily within rather than between guilds (Wilson &

Gitay 1995), the number of species representing each guild should be limited, thereby

resulting in relatively similar distribution of species across guilds (Fox 1989, Wilson

1989, Wilson & Roxburgh 1994, Wilson & Whittaker 1995). However, competition can

also structure communities by constraining the degree of “similarity” that is allowed

between co-occurring species (Case et al. 1983). Therefore, species that co-occur within

assemblages should differ in body size or morphology to reduce overlap in resource use

and allow for species coexistence (MacArthur & Levins 1967, Wiens 1982, Dayan &

Simberloff 2005).

If deterministic processes mediated by competition are responsible for structuring

mixed-species flocks, then I predict that (1) composition of observed flocks would differ

from flocks randomly generated from the regional species pool of flocking species, (2)

proportion of species within foraging guilds (i.e. frugivore, nectivore, insectivore, and

omnivore) would be similar across flocks in different regions (derived from Wilson 1989)

and (3) body sizes of species should show minimum overlap (Case et al. 1983).

Study area and methods

Study area

I sampled mixed-species flocks in the Northern and Central Andes, from Northern

Venezuela (± 10 o N, 61o W) to Southern Peru (± 13 o S, 78 o W), including Colombia and

Ecuador. Fieldwork was conducted in October-March 2007-2010, a period that typically

spans the wet (Oct-Nov) and dry (Jan-Feb) seasons in the Andes. Sites were located on

the Pacific and Amazon slopes of the Andes, as well as along the Magdalena and Cauca

12

interAndean Valleys in Colombia and on the Merida Cordillera in Venezuela. Study sites

represented a range of altitudinal diversity, from tropical lowlands at 400 m to low-

montane tropical forest at 2,600 m. Surveyed sites included evergreen tropical,

premontane and lower montane moist forest, evergreen tropical wet forest and

premontane dry forest (Holdridge 1967).

Flock sampling

Data on richness and size of mixed-species flocks were recorded in 20 geographically

separated clusters (hereafter termed “regions”) of 10-1 km2 pixels (i.e. 200-1 km2 pixels)

distributed across the Northern and Central Andes following a stratified random design

(Colorado et al. 2008; see Appendix A for methodology). Of the 20 regions initially

selected, 10 regions encompassing 43-1km2 pixels were visited and surveyed for flocks in

Venezuela (1 region, 4 pixels), Colombia (7, 34), Ecuador (1, 4) and Peru (1, 3; Table

2.1). For the purpose of my study, I grouped information for all pixels within each region,

thus focusing my analysis at the regional level. In addition, I included 2 additional

regions in Colombia (namely “SW Antioquia” and “Pacora”) that were frequently

searched and surveyed for flocks using the same methodology of non-systematic

observations (see below).

I recorded flock information using two techniques – systematic observations along line

transects and non-systematic observations. Within each pixel, three 100-m line transects

separated at least by 250 m were randomly placed to survey birds entirely within

dominant and relatively homogeneous habitats. Each transect was placed following the

same contour line, and the three transects were allocated across the pixel in order to

sample the range of elevations. Each of the three transects per pixel was surveyed at least

13

5 times for a minimum of 15 surveys per pixel typically within a 2-days period. Flocks

were recorded by one trained observer while walking transects at constant rate (ca. 30

min for the 100-m length). Surveys were conducted during peak activity, between the

first half hour after sunrise and 11:00 h and in the afternoon between 14:30 h and 17:00 h,

except during inclement weather. In addition, non-systematic observations of flocks were

conducted by walking and searching for flocks within and around the pixels, generally

within the same region or cluster. A mixed-species flock was defined as at least two

different species foraging and moving in a similar direction, with flock members less than

10 m apart (Morse 1970). For each flock, I recorded the species identity, number of

species and individuals participating in flocks. Observations of a flock seldom exceeded

15 min, as most members were detected within this period. Finally, I constructed a

regional species pool of flocking species for each one of the surveyed regions by

grouping together the species recorded in different mixed-species flocks in each region.

Statistical analysis

I used null model analyses (Gotelli & Graves 1996) and species- and trait-based

approaches to examine co-occurrence patterns in mixed-species bird flocks. I constructed

presence-absence matrices using the species pool of flocking species per region (i.e. 12

regions in total). A flocking species was defined as any bird that was found in at least one

flock in the region. The presence-absence matrix was constructed by assigning the flocks

to columns (analog to islands; Graves & Gotelli 1993) with rows representing flocking

species (see example in Appendix B). I first checked for similarity of pools of flocking

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species by region, and found that regions shared only ∼ 38% of the flocking species

(range 35%-53%). Therefore, each region was treated independently.

Indices of co-occurrence. I applied null model analyses to two indices of co-

occurrence (i.e. statistical indices), namely the C-score (Stone & Roberts 1990) and the

number of species combinations (Pielou & Pielou 1968). Each of these indices is

represented by a single number that summarizes co-occurrence patterns in a presence-

absence matrix (Gotelli 2000). Co-occurrence indices have long been used to test

assembly patterns in communities and their validity has been tested elsewhere (e.g.

Gotelli & McCabe 2002, Feeley 2003).

The C-score index quantifies the average number of “checkerboard units” between all

possible unique pairs of species in the assemblage. As the C-score is an index that is

negatively correlated with species co-occurrence, assemblages structured by competition

should have significantly more species pairs forming checkerboard units than expected

by chance (i.e., the C-score should be significantly larger than expected by chance;

Gotelli & McCabe 2002, Sanders et al. 2007, Krüger et al. 2010). This index supports the

fifth assembly rule by Diamond (1975), “5. Some pairs of species never coexist, either by

themselves or as part of a larger combination”.

The number of species combinations (Pielou & Pielou 1968) is another index of

community structure which states that in a competitively structured community (e.g. set

of islands or sites; Gotelli & McCabe 2002) there should be significantly fewer species

combinations than expected by chance because competition leads to combinations that

are unlikely to occur (Diamond 1975, Gotelli & McCabe 2002, Reshi et al. 2008). This

index is related to the first and second assembly rules by Diamond (1975), “1. If one

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considers all the combinations that can be formed from a group of related species, only

certain ones of these combinations exist in nature. 2. These permissible combinations

resist invaders that would transform them into a forbidden combination”.

Observed indices were compared with randomly generated indices (i.e. simulated

indices), obtained from the null model analysis (Manly 1995). To achieve this, the

original matrices were permuted 1000 times using Monte Carlo randomizations (Gotelli

2000, Feeley 2003, Sanders et al. 2007, Wallen et al. 2010). To create the null matrices

(i.e. randomly constructed assemblages without the influence of interspecific

competition), I used the Random Knight’s Tour algorithm (Gotelli & Entsminger 2005)

and row and column sums of the original matrix were held constant in all interations (i.e.

“fixed-fixed”sensu Gotelli 2000). The Knight’s tour is an algorithm that allows randomly

filling cells of an empty matrix until the imposed constraint (i.e. fixed row and column

totals) is violated. When a constraint is violated, the algorithm removes a filled cell and

begins the fill process again (Sanderson et al. 1998, Gotelli & Entsminger 2005). Null

models constructed using the Knight’s tour algorithm are unbiased and have been shown

to have good statistical properties, including good type I properties (low chance of falsely

rejecting the null hypothesis when it is true) and good power for detecting non-random

patterns in noisy data sets (Gotelli 2000, Gotelli & Entsminger 2005).

Guild proportionality. I also analyzed non-random patterns of flock assembly among

different foraging guilds (i.e. collection of species using the similar resources in similar

ways; Root 1967) by assessing whether the proportion of species within the selected

foraging guilds remained constant across flocks (Wilson 1989, Feeley 2003). I assigned

each of the bird species recorded to one of four foraging guilds (insectivores, frugivores,

16

nectarivores and granivores) determined by personal observations or following literature

(e.g. Terborgh 1990). I transformed the presence-absence matrix into a contingency table

such that each column represented a flock and each row represented a guild, following

Feeley (2003). Each cell of the new matrix represented the number of species of the

respective guild that occurred in a particular flock (Appendix C). I then analyzed this

contingency table using the log-likelihood ratio test (LLR) for homogeneity of repeated

samples (Sokal & Rohlf 1995), which determines if proportionality of guilds differs

significantly among flocks (i.e. P < 0.05), remains constant but with noise

(0.05<P<0.95), or remained fixed (P>0.95; sensu Feeley 2003). According to this model,

if competition is important at the guild level, the relative proportion of species within

each guild is expected to remain stable among islands (i.e. flocks) of varying species

diversity and composition (Wilson 1989, Mikkelson 1993, Wilson & Whittaker 1995).

Body-size overlap. I analyzed the non-randomness of flock assembly by analyzing

patterns of body size overlapping among species recorded in a flock. In this case, a flock

structured by competition should present species with differences in size with a minimum

overlap (Krüger et al. 2010), resulting as a mechanism allowing coexistence of apparently

similar species (Dayan & Simberloff 1994). Two metrics, the minimum size ratio and the

variance of size ratio were calculated between the body lengths (i.e. entire length

measured from the tip of the bill to the end of the tail feathers) of co-occurring bird

species separately for each flock. The observed indices were then compared to the

distribution of simulated indices generated from 5000 permutations, following Feeley

(2003). A competitively-structured community should contain species that generate an

unusually (1) large minimum size ratio and (2) small variance in the body size ratios

17

when compared to the null model. I used the uniform null model to generate flocks with

random body size distributions. In this model, the endpoints of the distribution are fixed

by the largest and the smallest species in the assemblage and the remaining species are

selected from a log uniform distribution within these limits (Gotelli & Ellison 2002,

Krüger et al. 2010). I used a binomial test to calculate the probability of finding the

observed number of flocks per site with minimum size ratios significantly greater than

expected by change as well as to estimate the probability of finding the observed number

of flocks per site with significantly less variance of size ratios than expected by chance

(Case et al. 1983, Feeley 2003). While the co-occurrence and the guild analyses account

for non-random patterns in both species distributions and functional differences in the

guild proportions, respectively, the body size ratio is complementary in incorporating

morphological differences among individuals within flocks. For example, if co-

occurrence or guild structure patterns are not different from the null hypothesis in either

ecological or taxonomic groups, mechanisms leading to co-existence are not expected to

be related to constant body size ratios (Hutchinson 1959).

For all statistical tests, an alpha of 0.05 was used to indicate statistical significance.

Mean values are reported with SD. Analyses were performed using EcoSim 7.0 (Gotelli

& Entsminger 2005), STATGRAPHICS Centurion XV (Statpoint 2005) and R version

2.11 (R Development Core Team 2009).

Results

I recorded 221 species participating in 311 flocks recorded in Venezuela (34 flocks),

Colombia (252), Ecuador (8) and Peru (17). Mean richness per flock was 8.24 ± 3.95

18

species (range 2-27), and average flock size (i.e., number of individuals) was 15.3 ± 9.3

(range 3-60; Table 2.2). Avian families most commonly detected in flocks were Tanagers

(Thraupidae: 48 species), Flycatchers (Tyrannidae: 36), and Ovenbirds (Furnariidae: 24,

Table 2.3 & Appendix D). Neotropical- Nearctic migrants comprised 10% of the species

recorded in flocks. Fifty-four species (24.4%) were only detected in a single flock among

the 311 flocks observed, whereas Blackburnian Warbler (Dendroica fusca) and Blue-gray

Tanager (Thraupis episcopus) represented the most abundant migrant and resident

species detected in flocks (62% and 31%, respectively; Table 2.4). Of the 221 flocking

species, the majority were insectivores (47%) and frugivores (45%). The remaining few

species were classified as either omnivores (5%) or nectarivores (3%).

The observed C-scores for the presence-absence matrices of mixed-species flocks for

the 12 regions across the Andes were significantly higher than expected by chance (i.e.,

significantly more checkerboard units between all possible pairs of species), suggesting a

negative pattern of species co-occurrence (Table 2.5). The index of number of species

combinations (Pielou & Pielou 1968) was less than expected by chance only for two

regions, Paya (observed No. of species combinations = 14, expected No. of species

combinations = 15, P < 0.01) and SW Antioquia (observed No. of species combinations =

82, expected No. of species combinations = 100, P < 0.01, Table 2.5).

The proportion of species within the selected four major foraging guilds remained

significantly stable among flocks in five regions (LLR Carache = 70.84, df = 99, P >

0.95; LLR Paya = 25.94, df = 42, P > 0.95; LLR Abejorral = 82.18, df = 105, P > 0.95;

LLR Pacora = 21.85, df = 42, P > 0.95 and LLR SW Antioquia = 187.54, df = 297, P >

0.95) as well as throughout all regions (Log-likelihood ratio = 809.98, df = 882, P > 0.95;

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Fig. 2.1). The proportion of species within each flock remained stable but with noise for

the rest of the regions (LLR Aguachica = 23.86, df = 22, P = 0.36; LLR San Jose de la

Montana = 77.68, df = 75, P = 0.39; LLR Yariguies = 13.58, df = 12, P = 0.33; LLR

Cauca = 81.99, df = 84, P = 0.54; LLR Sangay National Park = 24.85, df = 21, P = 0.25;

LLR Cajamarca = 47.15, df = 48, P = 0.51; LLR Chicamocha = 0.67, df = 2, P = 0.72

and LLR Tolima = 0.26, df = 1, P = 0.61 Fig. 2.1).

There was no evidence for morphological segregation of bird species within flocks

based on the body-size ratio model. Only five of 305 flocks had minimum body-size ratio

significantly greater than expected by chance (P < 0.05) distributed in four regions:

Carache in the Merida Cordillera of Venezuela (2 flocks out of 34), San José de la

Montaña in the Central Colombian Andes (1 out of 26), Abejorral in the Central

Colombia Andes (1 out of 36) and Pácora, Central Colombian Andes (1 out of 22).

Neither proportion represented a significantly greater number of flocks according to the

binomial test (P > 0.1; Table 2.6). Similarly, variance of body-size ratios was lower than

expected by chance for only 3 of 305 flocks (2 out of 34 in Carache and 1 out of 36 in

Abejorral), which was not a significant proportion of the flocks (P > 0.01, Table 2.6).

Conversely, the variance in body-size ratios was larger than expected by chance in 44 out

of 305 flocks, distributed across all the regions. However, the proportion of flocks with

larger variances was only significant in Carache (11 out of 34 flocks, Binomial test, P <

0.05).

20

Discussion

Despite the controversy associated with the deterministic view of community

assembly (Strong et al. 1984, Weiher & Keddy 1999, Hubbell 2001), a wide variety of

local to regional-scale studies have provided evidence that competitive interactions

among species can be a major driver of the assembly of plant and animal communities

(e.g. Gotelli & McCabe 2002, Krüger et al. 2010). Comparatively little work has been

conducted in social systems such as mixed-species flocks, which are known to be

strongly influenced by interspecific interactions (Graves & Gotelli 1993). My study

provides evidence of assembly patterns for mixed-species flocks in the Andes and further

suggests that competitive interactions at both interspecific and inter-guild levels play an

important role in structuring this social system in the Andes.

My findings of species co-occurrence are consistent with Diamond’s fifth assembly

rule (1975) that “some pairs of species never coexist, either by themselves or as part of a

larger combination”. Specifically, I found greater numbers of “checkerboard units”

between all possible pairs of species derived from the regional dataset of flocking species

than random flock assemblages. This pattern implies that certain flocking species are

consistently excluded from joining the same flock (e.g. Cerulean Warbler vs. bay-

breasted Warbler, Dendroica castanea, and Yellow-throated Bush-Tanager,

Chlorospingus flavigularis, vs. Common Bush-Tanager, C. ophthalmicus), and thus

provides some support for the hypothesis that interspecific competition structures flocks

(Graves & Gotelli 1993). Several studies have documented non-random patterns in

species co-occurrences in animal and plant communities (Cole 1983, Graves & Gotelli

1993, Gotelli & Ellison 2002, Sanders et al. 2003, Burns 2007, Reshi et al. 2008). In their

21

meta-analysis of co-occurrence patterns, Gotelli & MacCabe (2002) showed fewer co-

occurring species than expected by chance for a variety of taxonomic groups (e.g. birds,

bats, invertebrates, reptiles, amphibians and plants) and across spatial scales ranging

from small quadrats (0.25 m2) to large islands in oceanic archipelagos (2.3 x 1010 m2).

Specifically for flocks, Graves & Gotelli (1993) reported co-occurrence patterns of

species in permanent mixed-species flocks of Amazonian bids based on null model

analysis of 22 color-marked flocks. Since their work, no other study, to my knowledge,

has further explored co-occurrence patterns in tropical mixed-species flocks. My

contribution extends their findings on co-occurrence patterns to mixed-species flocks in

the Andes.

My data from flocks in the Andes do not provide strong support for the first and

second assembly rules by Diamond (1975), which predict fewer species combinations

than expected by chance and a limited number of permissible combinations. Although I

detected several flocking species that apparently never co-occurred in the same flock (e.g.

Yellow-throated Bush-Tanager, Chlorospingus flavigularis, vs. Common Bush-Tanager,

C. ophthalmicus), I did not find that closely-related species co-occurred less than

expected. I also detected fewer species combinations than expected by chance in two

regions out of 12, namely Paya and Southwestern Antioquia. Therefore, whereas Andean

flocks showed that some pairs of species do not co-occur in the same flock more often

than expected by chance, there were, to some extent, few apparent “forbidden

combinations” and flocks regularly supported related species.

Patterns of flock composition were consistent with the guild proportionality

hypothesis, thereby implying that assembly patterns in mixed-species flocks are at least

22

partially deterministic, guild-structured entities (Wilson 1999, Fargione et al. 2003).

However, the amount of noise varies among flocks across the study area, to the extent

that in some regions, such as Sangay National Park, some guilds tended to be

overrepresented in larger flocks (e.g. Frugivores tended to become dominant in larger

flocks). Empirical evidence for guild proportionality include studies on Alpha and Beta

guilds in plant communities along successional riverbed to grassland succesion sequences

in river terraces in New Zealand (Holdaway & Sparrow 2006), plant species in salt-

marshes under rabbit and wildfowl grazing in north Wales (Wilson & Whittaker 1995),

vegetation of dune slacks in west Wales (Wilson & Gitay 1995) and guilds stratification

in natural forests (Wilson 1989). The consistent proportion of species among different

foraging guilds provides indirect evidence that flocks are shaped by competitive forces

that align with the general principle of “limiting similarity” (Wilson & Roxburgh 1994,

Wilson et al. 2000, Fargione et al. 2003), in which species most strongly inhibit or limit

heterospecifics with similar patterns of resource use, usually from their own guild. Strong

within-guild competition should result in pattern of community assembly that tends

toward specific relative abundances of functional guilds (i.e. guild proportionality; Pacala

& Tilman 1994, Fargione et al. 2003). Particularly for birds, flocking species may

exclude other attendants with intra- or inter-specific antagonistic behaviors (Morse 1970,

Rappole & Warner 1980, Gaddis 1983, Ewert & Askins 1991, Latta & Wunderle 1996).

Such exclusion of species from flocks due to antagonistic behaviors are well-documented

in permanent Neotropical flocks containing territorial species, where flock participation

by any one species is limited to a single individual, mated pair, or family group (Munn &

Terborgh 1979, Powell 1979). Although I did not quantify behaviors in the field, I

23

commonly observed antagonistic interactions within and among species in my flocks,

especially among insectivorous birds, such as the Neotropical migratory parulids that

encompassed 47% of the migratory species participating in Andean mixed-species flocks.

Thus, antagonistic interactions might represent an important mechanism explaining the

patterns observed in guild proportionality. In addition, while insectivores are especially

likely to share similar broad preferences for feeding resources (i.e. insects) and

morphological characteristics (e.g. Johnson et al. 2005), interspecific competition may be

reduced by using specific foraging behaviors, substrates and preys (Curson et al. 1994,

Strong 2000).

Contrary to the co-occurrence and guild proportionality patterns in my data, structure

of my Andean flocks does not appear to be mediated by constant body-size ratios. There

was no evidence for a morphological segregation of avian species within flocks based on

the body-size ratio model (i.e. variance of body-size ratios was almost never found to be

significantly less than expected by change). Rather, greater variances of body-size ratios

were commonly detected in mixed-species flocks (∼ 15 % of flocks analyzed). Patterns of

greater variances suggest that, in general, Andean mixed-species flocks contained

aggregations of relatively small or large species (Krüger et al. 2010). Thus, some groups

of birds may show aggregation in sizes within flocks, instead of more constant body-size

ratio spacing. For example, tanagers and parulids, respectively, could be dominating the

distribution of body sizes in flocks in my study, allowing aggregated pattern.

Most community assembly studies, regardless of scale, have assumed that

communities are in an equilibrium state, and there has been little consideration of

whether co-occurrence patterns are stable in time or vary in space (Sanders et al. 2007).

24

Although I found non-random assembly patterns based on co-occurrence and guild

proportionality models in flocks joined by Neotropical migrants during the nonbreeding

season, I did not evaluate the potential association between interhabitat and temporal

variation and assembly patterns. Besides competition, available habitat and habitat

requirements of species are other important factors affecting the assembly of avian

communities (James 1971, James et al. 1984) that can profoundly influence flock

structure. Future work should therefore be directed to evaluate the stability of co-

occurrence patterns across gradients of anthropogenic disturbance and habitat

heterogeneity.

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34

Table 2.1. Site characteristics for 12 different regions on the Colombian, Ecuadorian and

Peruvian Andes where mixed-species flocks were recorded,October-March, 2007-2010.

Values are mean ± SD.

Locality Abejorral Pacora Tolima

South

Western

Antioquia

Rosas

Sangay

National

Park

Cajamarca

Country Colombia Colombia Colombia Colombia Colombia Ecuador Perú

Latitude 5.7125 5.4968 4.5042 5.8177 2.2292 -1.6625 -4.8125

Longitude -75.5208 -75.5895 -75.0125 -75.7961 -76.7375 -78.1875 -78.7291

Elevation

(m)

1188 ± 96 1338.2 ±

104.3

674.17 ±

185.2

1387.6 ±

52.1

1715.7 ±

361.9

1082.7 ±

115

1336.7 ±

250.3

Life zone Premontane

forest

Premontane

forest

Tropical

lowland

forest

Premontane

forest

Premontane

forest

Tropical

lowland

forest

Tropical

lowland

forest

Geographic

position

Central

Cordillera

Central

Cordillera

Central

Cordillera

Western

Cordillera

Western

Cordillera

Amazon-

Eastern

Ecuadorian

Andes

Amazon-

Eastern

Peruvian

Andes

35

Table 2.2. Mean number of species and individuals recorded in 311 flocks in 12 regions

in the Northern and Central Andes, October-March, 2007-2010. Values are mean ± SD.

Locality Country Mean No. of species Mean No. of individuals

Carache Venezuela 6.68 ± 3.91 12.47 ± 8.49

Aguachica Colombia 7.25 ± 2.9 13.67 ± 8

San Jose de la Montana Colombia 7.38 ± 2.45 14.31 ± 5.75

Yariguies Colombia 12.29 ± 3.99 30.29 ± 18.64

Chicamocha Colombia 4.33 ± 2.31 7.67 ± 5.51

Abejorral Colombia 9 ± 5.66 19.11 ± 12.95

Pacora Colombia 6.59 ± 2.4 12 ± 4.09

Paya Colombia 6.53 ± 1.68 12.4 ± 4.31

Tolima Colombia 6.5 ± 4.95 6.5 ± 4.95

Rosas Colombia 9.17 ± 3.95 15.21 ± 7.47

Sangay National Park Ecuador 5.88 ± 1.89 13.5 ± 4.14

Cajamarca Perú 7 ± 3.03 11.9 ± 6.93

Southwestern Antioquia Colombia 9.26 ± 3.71 16.11 ± 8.92

Total 8.24 ± 3.95 15.33 ± 9.3

36

Table 2.3. Number of bird species per family found in 311 mixed-species flocks recorded

in the Northern and Central Andes, October-March, 2007-2010.

Family No. of bird species

Capitonidae 1

Cardinalidae 10

Corvidae 1

Cotingidae 1

Cuculidae 1

Emberizidae 7

Fringillidae 6

Furnariidae 24

Icteridae 6

Incertae sedis 10

Mimidae 1

Parulidae 19

Picidae 11

Pipridae 3

Polioptilidae 1

Rhinocryptidae 1

Thamnophilidae 4

Thraupidae 48

Tityridae 3

Troglodytidae 7

Trogonidae 1

continued

37

Table 2.4 (continued)

Turdidae 11

Tyrannidae 36

Vireonidae 8

Total 221

38

Table 2.5. Percentage of most common bird species assisting mixed-species flocks in the

Northern and Central Andes. Species present in 10% or more of flocks are listed. Mean

abundance calculated for those flocks with the species present. Asterisk denotes

Neotropical-Nearctic migratory birds.

Species

Common name

% occurrence

in flocks

Mean abundance

± SD

Dendroica fusca* Blackburnian Warbler 61.9 2.78 ± 2.67

Dendroica cerulea* Cerulean Warbler 37.41 1.92 ± 1.09

Vermivora peregrina* Tennessee Warbler 32.65 2.39 ± 3.29

Thraupis episcopus Blue-gray Tanager 31.29 2.80 ± 2.44

Zymmerius chrysops Golden-faced Tyrannulet 25.51 1.32 ± 0.81

Hemithraupis guira Guira Tanager 23.81 2.07 ± 1.08

Mniotilta varia* Black and White Warbler 23.13 1.35 ± 0.71

Tangara vitriolina Scrub Tanager 22.11 2.45 ± 1.03

Parula pitiayumi Tropical Parula 20.07 1.46 ± 0.68

Wilsonia canadensis* Canada Warbler 18.71 1.16 ± 0.42

Myioborus miniatus Slate-throated Whitestart 17.35 2.43 ± 1.20

Tangara gyrola Bay-headed Tanager 16.67 2.35 ± 0.97

Tangara cyanicollis Blue-necked Tanager 16.33 2.04 ± 1.01

Basileuterus culicivorus Golden-crowned Warbler 14.29 1.45 ± 0.67

Vireo olivaceus* Red-eyed Vireo 13.61 1.33 ± 0.57

Coereba flaveola Bananaquit 13.61 2.25 ± 1.74

Piranga rubra* Summer Tanager 12.93 1.13 ± 0.34

Polioptila plumbea Tropical Gnatcatcher 12.24 1.56 ± 0.50

continued

39

Table 2.6 (continued)

Ramphocelus flammigerus Flame-rumped Tanager 10.54 3.00 ± 1.57

Pachyramphus polychopterus White-winged Becard 9.52 1.29 ± 0.46

40

Table 2.7. Result of three co-occurrence indices, C-score, number of species

combinations and checkerboard pairs, and the null model analysis for 11 sites in the

Andes. Expected score generated using the Knight’s Tour Algorithm. Fixed-fixed null

model (SIM9 in Gotelli 2000). P < 0.05*, P < 0.01**. Two localities, Chicamocha and

Tolima, were excluded due to small sample size (< 3 flocks).

Site Country Observed

C-score

Simulated

C-score

Observed species

Combinations

Simulated species

combinations

Carache Venezuela 10.44 10.07** 34 33.99

Aguachica Colombia 2.68 2.54** 14 13.99

San Jose de la Montana Colombia 5.08 4.89** 26 26

Yariguies Colombia 1.56 1.52* 7 7

Abejorral Colombia 9.53 9.03** 36 36

Paya Colombia 3.44 3.33** 14 15 **

Cauca Colombia 6.55 6.45* 29 29

Sangay National Park Ecuador 1.77 1.74** 8 8

Cajamarca Peru 2.36 2.17** 16 16

Pacora Colombia 7.19 1.14** 22 22

SW Antioquia Colombia 45.61 43.37** 82 100**

41

Table 2.8. Number of flocks that showed significant differences (P < 0.05) in the

minimum size ratios and the variance of size ratios when compared with randomly

generated flocks. After conducting the binomial test for greater minimum size ratios and

less variance of size ratios, no significant differences were found. Two localities,

Chicamocha and Tolima, were excluded due to small sample size (< 3 flocks).

Minimum size

ratio

Variance of size

ratio

Site Country Total #

flocks

Smaller Greater Smaller Greater

Carache Venezuela 34 23 2 2 11

Aguachica Colombia 12 9 0 0 2

San Jose de la Montana Colombia 26 14 1 0 1

Yariguies Colombia 7 7 0 0 2

Abejorral Colombia 36 12 1 1 4

Paya Colombia 15 13 0 0 1

Cauca Colombia 29 25 0 0 6

Sangay National Park Ecuador 8 6 0 0 1

Cajamarca Peru 16 9 0 0 2

Pacora Colombia 22 14 1 0 2

SW Antioquia Colombia 100 92 0 0 12

42

Figure 2.1.Relative proportion of flocking species in Andean flocks represented by each

foraging guild. Lines were constructed by regressing relative abundance vs. log flock size

(following Feeley 2003; for an example, see Appendix C). a. Carache; b. Aguachica; c.

San Jose de la Montana; d. Yariguies.

0

0.2

0.4

0.6

0.8

1

0.30 0.60 0.78 1.11

Prop

ortio

n of

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cies

in fl

ocks

Log flock size

0

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ortio

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in fl

ocks

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ortio

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in fl

ocks

Log flock size

0

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0.6

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0.85 1.11 1.28

Prop

ortio

n of

spe

cies

in fl

ocks

Log flock size

Omnivore

Nectarivore

Insectivore

Frugivorea b

c d

43

Figure 2.2.(Continued). e. Abejorral; f. Paya; g. Cauca; h. Sangay National Park.

0

0.2

0.4

0.6

0.8

1

0.30 0.70 0.90 1.26

Prop

ortio

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cies

in fl

ocks

Log flock size

0

0.2

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0.60 0.85

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ortio

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in fl

ocks

Log flock size

0

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0.48 0.85 1.04

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ortio

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cies

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ocks

Log flock size0

0.2

0.4

0.6

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0.60 0.70 0.90

Prop

ortio

n of

spe

cies

in fl

ocks

Log flock size

Omnivore

Nectarivore

Insectivore

Frugivoree f

h g

44

Figure 2.3.(Continued). i. Cajamarca; j. Pacora; k. Southwestern Antioquia; l. All

localities together.

0

0.2

0.4

0.6

0.8

1

0.48 0.90 1.11

Prop

ortio

n of

spe

cies

in fl

ocks

Log flock size

0

0.2

0.4

0.6

0.8

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0.48 0.78 1.04

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ortio

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cies

in fl

ocks

Log flock size

0

0.2

0.4

0.6

0.8

1

0.60 0.85 0.90 1.00 1.04

Prop

ortio

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cies

in fl

ocks

Log flock size

0

0.2

0.4

0.6

0.8

1

0.3 0.7 0.8 1.0 1.2

Prop

ortio

n of

spe

cies

in fl

ocks

Log flock size

Omnivore

Nectarivore

Insectivore

Frugivorei j

k l

45

3 MULTISCALE INFLUENCE OF DEFORESTATION AND HABITAT

ALTERATION ON NEOTROPICAL-NEARCTIC MIGRATORY BIRDS AND

MIXED-SPECIES FLOCKS IN THE ANDES

Abstract. Understanding how anthropogenic disturbance and deforestation affect the

suitability of wintering grounds remains a key issue in the ecology and conservation of

migratory birds. In this study, I examined the association of landscape-scale (i.e.

percentage of forest cover within 1-km2) and microhabitat level (i.e. habitat complexity)

factors on richness and abundance patterns of Neotropical-Nearctic migrants and mixed-

species flocks within five broadly-defined habitat types (shade coffee, pastures with

isolated trees, successional, secondary forest and mature forest) throughout the Northern

and Central Andes. From 2007-2010, I conducted systematic avian surveys along line

transects at 84 1-km2 pixels distributed from Colombia to Peru based on a stratified-

random design. Greatest richness and abundance of migrants and flocks were detected in

forested habitats such as secondary forest and shade coffee. Forest cover tended to

promote species richness and size of flocks, though the strength of association was

habitat-dependent. Whereas habitat complexity was positively associated with flock size

and migrant abundance and diversity in successional and silvopastoral habitats, the

opposite pattern was true in shade coffee and secondary forests. As a whole, richness and

abundance of Neotropical-Nearctic migrantory birds and encounter rates of flocks were

46

poorly explained by simple metrics of forest cover and habitat complexity. My research

supports the idea that intensively managed habitats with overstory trees can contribute to

avian conservation by supporting mixed-species flocks. However, the extent to which

restoration and management at regional (e.g., forest protection) and local (e.g., increasing

structural complexity) scales improve ecological conditions for birds cannot be

generalized since it is habitat specific.

Key words: Neotropical-Nearctic migratory birds, mixed-species flocks, Andes, forest

cover, habitat complexity, shade agriculture, silvopasture.

Introduction

The tropical Andes (hereafter the Andes) are widely recognized as one of the

world´s great centers of biodiversity (Rodríguez-Mahecha et al. 2004). High levels of

both species richness and endemism coupled with one of the greatest rates of

deforestation among tropical forests (Whitmore 1997, Wright 2005) have made the

Andes a major focal point for international conservation (Orme et al. 2005). With more

than 70% of the original cover already transformed, the region accounted for more than

one-third of the global forest area that was loss from 2000 to 2005 (FAO 2009). Despite

current and expected increases in deforestation, habitat degradation and fragmentation of

Andean forests, little is still known on the responses of species and key ecological groups

to these processes. Studies on anthropogenically-altered environments have provided

evidence of the effect of landscape matrix on avifauna (Soulé et al. 1988, Harris & Silva-

Lopez 1992, Enoksson et al. 1995), in particular for boreal and temperate birds (Flather

& Sauer 1996, Jokimaki & Huhta 1996, Bayne & Hobson 1997). Much of this research

47

has been conducted in Neotropical lowland ecosystems (e.g. Laurance & Bierregaard

1997, Maldonado-Coelho & Marini 2001, 2004), and comparatively little work has been

done in montane forests in the Andes. Previous studies in Andean and subandean forests

have shown that the nature of the landscape matrix is a major factor influencing resident

bird composition and abundance (Restrepo & Gomez 1998, Renjifo 1999, 2001).

Resident birds are known to be sensitive to high rates of nest predation in fragmented

landscapes (Kattan 1994, Renjifo 1999, 2001), especially for extinction-prone

insectivores and large frugivores (Bierregaard et al. 1992, Karr 1982, Sekercioglu et al.

2002, Renjifo 1999, Kattan et al. 1994).

The effects of deforestation and habitat degradation extend beyond direct

population impacts on resident species and also can alter social systems (e.g., mixed-

species flocks; Maldonado-Coelho & Marini 2004, Lee et al. 2005) and wintering

species, including Neotropical-Nearctic migratory birds that rely on Andean forests

during the nonbreeding season (e.g. Robbins et al. 1989). Indeed, declines in populations

of Neotropical-Neartic migrants are frequently attributed, in part, to habitat degradation

and deforestation on wintering grounds (Terborgh 1980, Holmes & Sherry 1988, Faaborg

& Arendt 1989, Robbins et al. 1989, Rappole & MacDonald 1994). However, there

remain large gaps in our understanding of the sensitivity of migratory birds to large-scale

changes in land cover on wintering grounds. Observational and experimental studies have

linked declines in populations of Neotropical migratory birds to reduced food availability

and habitat complexity associated with diminishing habitat patch size and forest cover, as

well as the conversion of the landscape matrix from high to low-quality habitats (Rappole

& MacDonald 1994, Wunderle & Latta 1996, Johnson & Sherry 2001, Carlo et al. 2004).

48

Similarly, mixed-species flocks, a key widespread social system in tropical communities,

are reported to be negatively affected by habitat fragmentation and degradation in the

Neotropics (e.g. Harper 1989, Stouffer & Bierregaard 1995, Maldonado-Coelho & Marini

2004, Kumar & O’Donnell 2007). The structure and dynamics of mixed-species flocks

also are known to change as a consequence of habitat fragmentation and degradation

(Maldonado-Coelho & Marini 2000, 2004, Tellería et al. 2001) by way of alterations in

habitat characteristics (e.g. disappearance of microhabitats) and reduction in food

availability (Maldonado-Coelho & Marini 2000, 2004, Tellería et al. 2001). These factors

can affect this social system by changing the frequency of occurrence and abundance of

species within flocks as well as their propensity to flock (Stouffer & Bierregaard 1995,

Thiollay 1992, 1997, 1999, Van Houtan et al. 2006). Because many migratory birds

frequently join mixed-species flocks (Keast & Morton 1980, Robbins et al. 1989,

Rappole 1995), the overwinter condition of migratory species might depend upon

flocking social systems.

Although Neotropical migrants and mixed-species flocks represent important

components of montane forest bird communities in the Andes, no studies have examined

the sensitivity of both groups to forest loss and degradation across regional or landscape

scales. Several studies have shown the importance of the combined effect of

microhabitat, patch and landscape factors in the distribution and patch use of animals

(e.g. Levin 1992, Dooley & Bowers 1998, Lyra-Jorge et al. 2010), including birds (e.g.

Jokimäki & Huhta 1996, Saab 1999, Sodhi et al. 1999, Lee et al. 2002, Luck 2002, Buler

et al. 2007, Coreau & Martin 2007, Deppe & Rotenberry 2008). Particularly, most avian

49

landscape studies in the Neotropics have focused on the response of birds within forest

patches (e.g. Kattan et al. 1994, Stouffer & Bierregaard 1995, Renjifo 1999), and very

few studies have evaluated the simultaneous effect of multiple spatial scales (e.g. patch-

and landscape-levels) on distribution of birds in several habitat types (but see Graham &

Blake 2001). Given the high bird diversity and extensive levels of habitat degradation and

deforestation in the Andes, understanding the effect of landscape context on habitat

relationships is key to determining the conservation potential of different habitats.

In this study, I adopted a multi-scale approach to examine the extent to which

migratory birds and mixed-species flocks respond to changes in landscape forest cover

and in local habitat structure across a broad geographical range in the Andes. I

hypothesized that the value of different habitats to Neotropical-Nearctic migratory birds

and mixed-species flocks (as indicated by abundance and diversity metrics) would be

mediated by local and landscape-scale factors. To the best of my knowledge, this is the

first multi-scale study to test for the effects of deforestation and habitat degradation in the

Andes on mixed-species flocks and Neotropical-Nearctic migratory birds along a gradient

of habitat types.


Study area

The study area encompassed the Northern and Central Andes, from Northern

Colombia (± 8 o N, 73o W) to Northern Peru (± 5 o S, 78 o W), including Ecuador.

Ecosystems in the Andes are diverse, including deserts, open pampas, dry thorn forest,

deciduous forest, rain forest, cloud forest, and paramo above 3,000 m (Petit et al. 1995).

50

The study area represented a range of altitudinal diversity, from tropical lowlands at 400

m to low-montane tropical forest at 2,600 m.

I studied five broadly-defined habitat types in the Andes: shade coffee, pastures with

isolated trees (hereafter termed “silvopastures”), successional, secondary forest and

mature forest (Figure 3.1). In this respect, my study differs from most others that focused

exclusively on mature forest in human-dominated matrices (e.g. Stouffer and Bierregaard

1995).

• Shade coffee (usually Coffea arabica) is planted under a layer of trees that dominate

the canopy, typically represented by Inga spp.(Mimosaceae), Tabebuia spp.

(Bignoniaceae), Cordia alliodora (Boraginaceae), Albizia spp. (Mimosaceae), and

Persea spp. (Lauraceae). This habitat type is usually located between 800 and 2,000

m of elevation and it is distributed virtually throughout my study area in the Andes.

• Silvopastoral systems with grazed fields and mature overstory trees were included as

a focal habitat type because they represent an increasingly popular land use that

supports livestock, produce timber, and contribute to ecological restoration efforts by

providing habitat for other species as well as improving soil conditions (Pomareda

2000). While the overstory component of silvopastures structurally resembled the

most open shade coffee farms, silvopastures generally lacked shrubs and dense

understory.

• Successional habitats are typically represented by second-growth habitats, with little

or no tree development (< 10 cm dbh), open canopy, and usually with poorly-

developed shrub layer (< 1 m height).

51

• Secondary forests represented naturally regenerating and riverine forests (i.e., not

planted or otherwise intensively managed) in intermediate to advanced levels of

structural (trees > 10 cm dbh and < 10 m height) and composition development (i.e. >

12 years old).

• Mature forests were structurally complex (high and dense canopy > 10 m height, high

basal area) and floristically diverse habitats with relatively little human use. Mature

forests usually occurred in association with reserves and Important Bird Areas, where

human extractive uses were largely prohibited.

Bird sampling

Data on composition, richness and abundance of migratory birds and mixed-

species foraging flocks were recorded within 1-km2 pixels distributed across the Northern

and Central Andes following a stratified random design (for details see Colorado et al.

200 and Appendix A for a summary of the methodology). Of the 200 1-km2 pixels

initially selected for survey, 84 were visited across 11 different regions (i.e. landscapes)

in Colombia (72 pixels), Ecuador (9) and Peru (3; Figure 3.2; Table 3.1). Neotropical-

Nearctic migrants were surveyed at each of 84 1-km2 pixels, but flock data were obtained

for only 39 1-km2 pixels. Surveys were conducted in October-March 2007- 2010, a

period that typically spans the wet (Oct-Nov) and dry (Jan-Feb) seasons in the Andes and

is unlikely to include the migratory period for most focal species. Within each pixel, three

100-m line transects were randomly placed to survey birds entirely within dominant and

relatively homogeneous habitats; transects were separated at least by 250 m, followed a

constant elevation, and sampled the range of elevations within the pixel (Figure 3.3).

Each of the three transects per pixel was surveyed at least 5 times for a minimum of 15

52

surveys per pixel typically within a 2-day period. Transects were walked at constant rate

(ca. 30 min for the 100-m length) and all Neotropical- Nearctic migratory birds seen or

heard were recorded by a single observer. Surveys were conducted during peak activity,

between the first half hour after sunrise and 11:00 h and in the afternoon between 14:30 h

and 17:00 h, except during inclement weather. For each individual detected,

perpendicular distance from the bird to the main transect line was visually estimated to

allow later correction for detection probability within each habitat type (Bibby et al.

1992, Thomas et al. 2006).

Flock sampling

I recorded size and species composition of mixed-species flocks encountered

during transect surveys. A mixed-species flock was defined as at least two different

species foraging and moving in a similar direction, with flock members less than 10 m

apart (Morse 1970). Because the boundaries of a flock are continually changing and not

immediately evident to a field observer, I was unable to record distance from transects

and apply distance-based sampling techniques to individuals within flocks. However,

birds foraging in flocks frequently vocalize with contact or alarm calls, and this behavior

improves the likelihood of detecting flocking individuals even in vegetatively-dense

habitats. For each flock, I recorded the number and identity of species and individuals

participating in flocks. For each region/cluster, I calculated flock encounter rate as the

number of flocks encountered per hour of survey. Observation of a flock lasted 15 min,

as most members were detected within this period. I developed a list of regional species

richness of flocking species by pooling all species detected during surveys, flock

53

observations, and incidental observations (Latta & Wunderle 1996, Maldonado-Coelho &

Marini 2004).

Vegetation sampling

Habitat structure was measured along each 100-m line transect using a modified

James & Shugart (1970) method. Two 0.04-ha circular plots were established at two

points randomly selected at 0, 20, 40, 60, 80, or 100-m along each transect. When

adjacent points were selected for sampling, plots were relocated to the adjacent point so

they did not overlap. The following variables were recorded within each plot: tree

density (number of stems ≥ 7.6 cm dbh per ha), shrub density (shrub stem count in two

perpendicular two arm-wide times plot radius length rectangular subplots, < 7.6 dbh),

percentage of canopy cover, percentage of ground cover (< 0.5 m), basal area (m2 per ha),

and canopy height (mean of five-randomly selected trees ≥ 7.6 cm dbh). Because

vegetation variables were highly correlated (Table 3.2), I used principal components

analysis to create a composite measure of structural complexity. A metric of regional

forest cover was calculated using ArcView GIS (Version 3.3, Environmental Systems

Research Institute 2002) to quantify the proportion of forest cover within 1-km2 using

500 m x 500 m images from the Global Land Cover Facility MODIS (2001).

Statistical analyses

Abundance estimates based on transect data were corrected for differences in

detection probability using program DISTANCE (Thomas et al. 2006). I lacked

sufficient numbers of detections to estimate detection probability for individual species

and, consequently, used DISTANCE to calculate a global detection function for each

54

habitat based on the four most abundant species: Tennessee Warbler (Vermivora

peregrina), Blackburnian Warbler (Dendroica fusca), Red-Eyed Vireo (Vireo olivaceus)

and Summer Tanager (Piranga rubra). Use of a global detection function also was

biologically valid because most migratory species co-occurred in mixed-species flocks.

To account for the differences in sampling (i.e. number of flocks and individuals) among

habitat types, I calculated sample-based rarefaction curves (i.e. smoothed accumulation

curves) rescaled to the number of individuals to compare the number of mixed-species

flock species among habitat types (following Lee et al. 2005). Samples are rarefied to the

same number of individuals (i.e. rescaling by individuals) to allow a valid comparison of

species richness among datasets (Gotelli and Colwell 2001).

I used χ2 to test how flocking frequency of Neotropical migrant species differed

among habitats. Flocking frequency of species was defined as the proportion of mixed-

species flocks in which each migratory species participated across habitats. Species that

flocked significantly less frequently (P < 0.05) in disturbed/deforested habitats were

classified as “sensitive”, whereas the remaining species can be classified as “persistent”

(sensu Lee et al. 2005).

Flock composition among habitats was compared with a two-step procedure.

First, I performed a multi-response permutation procedure (MRPP) to obtain a non-

parametric multivariate test of compositional differences in the mixed-species flocks

among habitats. MRPP is based on an analysis of a rank-transformed distance matrix,

55

adopting Sorensen (Bray-Curtis) distance as the distance measure. MRPP tests if the

within-habitat average dissimilarities are smaller than predicted at random (McCune &

Grace 2002), with a significant MRPP test (i.e. P < 0.5) indicating that flock composition

is more similar within than between habitats. Second, I ran an indirect gradient analysis

with non-metric multidimensional scaling (NMS) to ordinate sample units (i.e. 186

mixed-species flocks) in species space (i.e. 220 bird species), using presence-absence of

species in mixed-species flocks. To facilitate interpretation, I plotted the sample scores

(i.e. mixed-species flocks) in the species space on the first and third NMS axes to

graphically show the relative similarity in flock composition among more contrasting

habitats. NMS is similar in general purpose and philosophy to principal component

analysis (i.e. creating composite variables that summarize the dissimilarities in species

composition of the flocks), but reduces the dimension of the data in a nonlinear approach,

and allows the use of non-parametric tests (Péron & Crochet 2009). The NMS procedure

was run using the “autopilot (slow and thorough)” mode with random starting

configuration and applying the same distance measure used in the MRPP (i.e. Sorensen

distance) as a dissimilarity measure, as suggested by McCune & Grace (2002). Both

techniques have previously been used for the analysis of mixed-species flock

composition (e.g. Lee et al. 2005, Péron & Crochet 2009).

Neotropical-Nearctic migrants and mixed-species flocks. I assessed the

relationship between the occurrence of Neotropical migrant species and flock attributes

(i.e. flock richness and flock occurrence) with a multiple regression analysis including

flock size as a dummy variable since this is highly correlated with Neotropical migrant

56

attributes (Neotropical migrants in flocks vs. flock size: r = 0.62, P = 0.0, N = 39;

Neotropical migrant richness per site vs. flock size: r = 0.46, P = 0.003, N = 39).

Species associations with environmental variables at the large and small scales. I

used the Akaike’s Information Criterion corrected for small sample size (AICc; Burnham

& Anderson 2002) to identify the set of environmental variables that best explained

flocks and Neotropical migrants attributes across the Andes. Separate analyses were

completed for flocks (richness, abundance, and encounter rate used as response variables)

and Neotropical migrants (richness and abundance in flocks, richness and abundance on

survey transects).I developed an a priori set of 11 candidate models (Table 3.3)

hypothesized to influence abundance and composition of migratory birds and mixed-

species flocks. Each model was run using a regression analysis on the identical data set

(i.e., pixels without missing data). AIC values were calculated based on the log-

likelihood function and models were ranked according to difference (Δi) from the best

model. Models with Δi < 2 were considered to have a strong empirical support and

general linear models on these models were subsequently run to obtain regression

coefficients to describe the nature (positive/negative) of the associations. Akaike model

weights (wi) were used to indicate the relative weight of evidence for each of the

candidate models. To facilitate interpretation, I used the regression equations of the top-

ranked models to graphically assess the response of the Neotropical migrant and flock

attributes by habitat type to changes in the environmental variables by assigning values to

the two major predictor variables (i.e. forest cover and local habitat structure).

57

For all statistical tests, an alpha of 0.05 was used to indicate statistical

significance. Mean values are reported with SD. I conducted log-transformation (Y + 0.5)

for those variables that did not fulfill the normality and homogeneity of variance criteria

and they were back-transformed later for interpretability. Analyses were performed using

EstimateS Version 8.0 (Colwell 2006), Distance 5.0 (Thomas, et al. 2006), PC-ORD

version 5 (McCune & Mefford 1999), R version 2.11 (R Development Core Team 2009),

STATGRAPHICS Centurion XV (Statpoint 2005) and Minitab (Minitab Inc. 2007).

Results

Habitat and landscape attributes

The first principal component explained nearly 75% of the variance in local

habitat structure (Table 3.4) and represented a gradient of habitat complexity that was

associated with anthropogenic changes in the landscape. Increasing values indicated

increasing basal area, canopy height, and tree density.

Structural development and horizontal vegetation volume (e.g. canopy height, tree

density and shrub density) were higher in primary forests of the Cordillera del Cóndor in

Perú (Average percentage of forest cover: 72.8) and lower in the dry valleys of the

Chicamocha River (13.5; Figure 3.4). The former location, along with Serrania de los

Yariguies National Park in Colombia and Sangay National Park in Ecuador, represent the

most vegetatively dense sites visited (Figure 3.4, Table 3.4). On the other hand, the dry

valleys of the Chicamocha River along with the Patia region in Colombia, had less

structural complexity (farthest left along PC1, Figure 3.4, Table 3.4), which is consistent

58

with the harsh environmental conditions and extensive areas of exposed soils and

savannas.

Percentage of forest cover within 1 km2 differed among habitats (ANOVA, F4, 240

= 15.11, P < 0.001); forested habitats (mature forest = 57.66 ± 10.23, shade coffee =

46.75 ± 14.62) were surrounded by > 12% more forest cover than other habitats

(silvopastures = 31.24 ± 17.89, successional = 34.86 ± 15.53; Figure 3.5). Similarly,

habitat types significantly differed in habitat complexity (ANOVA, F4, 79 = 25.35, P <

0.001), with mature and secondary forest being significantly more complex (2.47 ± 0.29

and -0.24 ± 0.22, respectively) than other habitats (shade coffee = -0.89 ± 0.41,

silvopastures = -0.97 ± 0.32 and successional = -1.23 ± 0.35). Local structural complexity

of habitat (i.e. PC1) was positively associated with forest cover within 1-km2 (r = 0.58, P

< 0.001, N = 84 pixels; Figure 3.6).

Avian communities

I recorded 220 avian species from 27 families in 186 mixed-species flocks in

Colombia (130 flocks), Venezuela (47), Ecuador (8), and Peru (1) during flock surveys,

with an average number of species of 7.91 ± 4.19 (range 2-21) and average number of

individuals of 15.56 ± 10.11 (range 3-52). Avian families most represented in the flocks

were Thraupidae (N = 46 species) and Tyrannidae (N = 35 species). Differences in

sampling effort contributed to uneven distribution of flock observations among

successional (23 flocks), silvopastures (13), shade coffee (48), secondary forest (81) and

mature forest (21). However, after adjusting for effort, flocking frequency of all

59

migratory species was similar among the five habitat types surveyed (χ2 ≤ 6.87, P > 0.1,

df = 4), except for the Rose-breasted Grosbeak (χ2 = 10.91, P = 0.03, df = 4), which

flocked significantly less frequently in natural habitats than in shade coffee.

Of the 30 Neotropical-Nearctic migratory landbird species recorded, 20 (67%)

joined mixed-species flocks. Four Neotropical migrants were among the fifteen most

abundant bird species found in mixed-species flocks in the Andes (Table 3.5).

Blackburnian Warbler was found in nearly half of the flocks detected, Tennessee Warbler

in ∼ 20% of flocks, and Cerulean and Canada Warblers in ∼ 10% of flocks (Table 3.5).

Likewise, the most geographically widespread migrants were Blackburnian Warbler,

Tennessee Warbler, Empidonax Flycatchers, Red-eyed Vireo, Summer Tanager and

Swainson’s Thrush, with the latter being the species detected farthest south of the entire

surveyed range (Figure 3.7).

The majority of Neotropical migrants (24 of 30 species) were recorded in

premontane forests at 1000 - 2000 m elevation and between 2-8 o N in latitude, and 73-77

o W in longitude (Figure 3.8). However, after accounting for regional forest cover, neither

Neotropical migrant richness nor abundance were correlated with latitude (F1, 81 = 1.33, P

= 0.25 and F1, 81 < 0.01, P = 0.95, respectively) or elevation (F1, 81 = 0.28, P = 0.6 and F1,

81 = 0.46, P = 0.5, respectively).

As expected, flock richness increased strongly with flock size (r = 0.87, P < 0.01,

N = 186 flocks). Richness of flocks was positively related to regional avian richness (r =

0.64, P = 0.035, N = 11 regions). After accounting for flock size, mean Neotropical

60

migrant richness was positively related to both mean total richness per flock (F2,36 = 10.8,

P < 0.01) and flock occurrence (F2,36 = 8.33, P < 0.01; Figure 3.8). Flocks in forested

habitats (i.e. secondary forest, mature forest, silvopasture and shade coffee) gained

species more rapidly and had higher total numbers of species than in degraded

successional habitats (Figure 3.9). Mean species richness (± 95% confidence intervals) in

flocks was 8.9 ± 1.2 in shade coffee, 8.7 ± 3.1 in silvopastures, 7.8 ± 1 species in

secondary forest, 7.4 ± 1.5 in mature forest, and 5.1 ± 1 in successional. Different levels

of Neotropical migrant species richness in flocks were present in all five habitat types,

with flocks in mature forest showing the smallest expected number of migrants (Figure

3.10). Mean species richness (± 95% confidence intervals) of Neotropical migrants in

flocks was 2.1 ± 0.5 in shade coffee, 1.5 ± 0.76 in silvopasture, 1.3 ± 0.3 in secondary

forest, 1 ± 0.46 in mature forest and 0.9 ± 0.5 in successional.

Comparisons of flock composition among habitats based on average within-group

distances showed that all groups (i.e. habitats) had relatively high dispersions (> 0.6;

MacCune and Grace 2002; Table 3.6), and the species composition of mixed-species

flocks significantly differed among habitats (T = -12.095, P < 0.01; Table 3.6). Within

habitats, species composition of flocks was more similar within shade coffee than other

habitats (Figure 3.11), and most dissimilar within successional habitats (Table 3.6).

Among habitats, the greatest heterogeneity (A < 0.1) was found between flocks in

degraded and non-degraded habitats, whereas high homogeneity (A > 0.1) was recorded

among flocks in degraded habitats (Table 3.6).

61

Mixed-species flocks attributes (i.e., encounter rate, size, and species richness)

were best explained by the combined effect of patch- (habitat characteristics) and

landscape-scale (regional forest cover) factors (Table 3.7). Richness of mixed-species

flocks was positively associated with landscape-scale forest cover in all but one habitat

(mature forest), and the positive association between regional forest cover and flock

richness was more evident in less-structured habitats (successional and silvopastures,

Figure 3.12; Appendix E and Appendix F). Flock size increased with forest cover in

silvopastoral, successional and secondary forest, but did not increase in shade coffee and

mature forest (Figure 3.13). Flock encounter rate increased with surrounding forest cover

(when >40% forested) in shade coffee (0.59 ± 0.14 flocks·h-1) but was virtually invariant

across landscapes for secondary forest (0.4 ± 0.1 flocks·h-1), silvopastures (0.3 ± 0.13

flocks·h-1), successional (0.2 ± 0.11 flocks·h-1) and mature forest (0.05 ± 0.16 flocks·h-1)

habitats (Figure 3.14).

Increased habitat complexity seemed to promote diversity and abundance of

flocks in less-structured habitats (Figure 3.15 & Figure 3.16; Appendix F and Appendix

G). Flock richness increased with habitat complexity in more degraded habitats (i.e.

successional) and secondary forests, and tended to decrease in shade coffee and mature

forests. Small changes in habitat complexity enhanced the abundance of flocking species

in successional and silvopastoral habitats. For example, increases as small as ∼ 20% in

habitat complexity doubled the amount of individuals in flocks in these habitats. By

contrast, flock size declined with increasing structural complexity in mature forest and

62

shade coffee (Figure 3.16). Finally, flock encounter rate appeared insensitive to changes

in habitat complexity in all habitats (Figure 3.17).

Variation in richness and abundance of Neotropical migratory birds detected

along transects was explained by strong interactions among local-, patch- and landscape-

scale environmental factors (Table 3.8; Appendix H). The relationship between forest

cover and Neotropical migrant richness was weak, and migrants seemed to tolerate

variation in the amount of regional forest cover (Figure 3.18; Appendix H). Abundance

of migrants detected along transects in shade coffee was strongly and positively

associated with increasing forest cover (Figure 3.19).

Attributes of Neotropical migrants were most strongly associated with changes in

structural complexity in agroforestry/silvopastoral systems (Figure 3.20 & Figure 3.21).

The number of Neotropical migrant species was positively related to improvement in

structural complexity only in shade coffee. Similarly, complexity was positively

associated with abundance of Neotropical migrants in shade coffee and silvopastures.

Finally, there were no distinctive patterns in attributes of Neotropical migrants in

secondary, mature and successional habitats with changes in habitat complexity (Figure

3.20 & Figure 3.21).

Discussion

Working across broad latitudinal and altitudinal gradients in the Tropical Andes, I

found evidence that Neotropical-Nearctic migratory birds and mixed-species flocks are

sensitive to habitat changes across multiple scales. Although these montane birds were

63

sensitive to landscape-scale forest cover, patterns of response were habitat-dependent

(Table 3.9). Deforestation and habitat degradation in the Neotropics are widely

recognized among the most important threats to bird populations (e.g. Terborgh 1980,

Faaborg & Arendt 1989, Robbins et al. 1989, Rappole & MacDonald 1994), but our

current knowledge has largely been based on studies in Neotropical lowlands (e.g.

Laurence & Bierregaard 1997) with some limited work on resident Andean avifauna

(Kattan et al. 1994, Restrepo & Gomez 1998, Renjifo 1999, 2001). Even less research in

the Andes has focused on wintering populations, such as Neotropical-Nearctic migrants,

and social systems such as mixed-species flocks. Hence, my study fills some of these

gaps in knowledge by suggesting that deterministic ecological processes, such as

deforestation and changes in habitat structure, influence Andean forest bird communities.

Both mixed-species flocks and Neotropical-Nearctic migrants were detected at

∼85 % of my randomly-selected study locations, which highlights that flocks are

important components of montane forest ecosystems across the Northern and Central

Andes. My findings are similar to reports that 5 - 20% of tropical avian communities are

represented by migratory birds, and up to 80% of these species can participate to some

extent in flocks (e.g. Rappole & Warner 1980, Robbins et al. 1989, Hutto 1994, Latta &

Wunderle 1996, Maldonado-Coelho & Marini 2000, 2004, Lee et al. 2005, Sridhar &

Sankar 2008). Across the Andes, approximately 65% of the migratory species recorded

during surveys attended mixed-species flocks, and 25% of the most common flocking

species were migratory. Thus, migrants are not only an important component of avifauna

in the Neotropics, but likely play an important role in maintenance of flocking systems

during the non-breeding period.

64

I found that patterns in flock and migrant attributes were well explained by

environmental heterogeneity at multiple spatial scales, though habitat-specific

associations depended upon the landscape context. Poulin & Lefebvre (1996) showed

that Neotropical migrants depended upon intact humid lowland forests in central Panama

for food requirements. Similarly, Marra & Holmes (2001) showed that American

Redstarts wintering in xeric forest or successional habitats in Jamaica performed poorly

compared to those in mature mesic forest or mangrove habitats.

Despite complex interactions among landscape, habitat, and microhabitat

attributes, my results indicate that regional forest cover may play an important role in

determining suitability of nonbreeding habitat for overwintering migratory birds, but

apparently not as important as for mixed species flocks. Increasing amounts of forest

cover were generally associated with increasing the size and the richness of flocks. In my

study areas, migrants were consistently underrepresented in less disturbed mature forest.

Though Neotropical migrants were found in areas with regional forest cover as low as

~10% of a 1-km2 area, certain species of conservation concern, such as Cerulean

Warbler, Canada Warbler and Golden-winged Warbler, showed higher thresholds and

occurred only in landscapes with >20% forest cover within 1-km2 area. Because

Neotropical migrants seem are readily observed in disturbed landscapes, some have

suggested that wintering Neotropical migrants are less sensitive to forest cover than

during the breeding season (Robbins et al. 1987, 1992, Askins et al. 1992). Indeed,

several studies have reported that disturbed forests contained more Neotropical migrants

than undisturbed forests, suggesting that small-scale activities, forest openings, and other

minor-to-moderate disturbances enhance the suitability of forested habitats for many

65

species of over-wintering migratory birds (Orejuela et al. 1980, Pearson 1980, Petit et al.

1995). However, other empirical studies have demonstrated that migratory species are

highly dependent upon undisturbed forest while on their wintering grounds (e.g. Petit et

al. 1993).

Regional forest cover may be most important in landscapes surrounding

successional habitats and shade coffee. For example, an increase in ∼ 40% of regional

forest cover was associated with a ~ 25% increase in abundance of Neotropical migrants

in successional habitats and a ∼ 50% increase in shade coffee. My results then are

consistent with a large number of studies that document the importance to birds of forest

habitat availability in fragmented landscapes (e.g. McGarigal & McComb 1995, Saab

1999, Renjifo 2001, Lee et al. 2002, Cleary et al. 2005). Moreover, crops such as coffee

benefit from pollination services provided by nearby forests or other natural habitats,

which offer forage and nesting space for pollinators, and increasing forest conversion

may have negative effects on pollinator diversity (Ricketts 2004). Priess et al. (2007)

found for different landscapes with forest patches and coffee plantations in Indonesia,

that forest reduction and the associated decline in pollinators may directly reduce coffee

yields. Interestingly, Neotropical migrants were less sensitive to changes in regional

forest cover surrounding other habitat types, such as secondary forests. Thus, the strength

of the association between regional forest cover and Neotropical migrants seemed to be

habitat-dependent.

Habitat complexity, particularly as related to overstory trees, was most strongly

related to migratory birds in shade coffee and silvopastoral habitats. In these habitats,

increases in complexity of ∼15% to 20% resulted in a one-fold increase in numbers of

66

Neotropical migrants, suggesting that large gains may result from relatively small

changes in habitat management. Increasing the overstory tree component may produce

especially strong results, as Cerulean Warbler, Canada Warbler and Golden-winged

Warbler were virtually absent from sites with less than 45% of canopy cover. Tree-

dominated habitats, in particular shade coffee, are known to hold high conservation value

for resident and migratory birds (Robbins et al. 1992, Wunderle & Waide 1993,

Wunderle & Latta 1996, Greenberg 1997, Wunderle & Latta 2000, Tejeda-Cruz &

Sutherland 2004, Johnson et al. 2006), often supporting more migratory species because

the diverse floristic and multi-layer canopy structure of the shading trees (Robbins et al.

1992, Wunderle & Waide 1993, Greenberg et al. 2000, Johnson & Sherry 2001, Carlo et

al. 2004, Johnson et al. 2005). Wunderle & Latta (2000) showed, for example, that

overwinter site persistence and annual return rates of Neotropical migrants in shade

coffee plantations, fell within the average values reported for native forests. Moreover,

Bakermans et al. (2009) demonstrated not only that shade coffee harbored higher

densities of Neotropical migrants than primary forest, but also that several migratory

species significantly improved their body condition through the winter months.To some

extent, the arboreal component in silvopastures may provide some ecological services

resembling those by shade coffee, in particular leguminous trees such as Inga spp. and

Albizia spp., which may partially explain the similar use of silvopastures and shade

coffee. Tree-dominated habitats also may play an important role in establishing or

retaining connectivity among habitat patches in fragmented landscapes. For example,

resident and migratory birds were more reluctant to cross an open field without trees than

one with overstory trees (pers. obs.). Thus, my study further suggests that even in highly

67

disturbed landscapes, managing for increased structural complexity in the matrix may

positively influence Neotropical migrants. Several tropical studies have shown that the

type of matrix surrounding a particular patch may influence the movement of bird species

between patches of habitat and that more structurally complex matrices enhance bird

diversity and mobility, particularly for forest birds (Stouffer & Bierregaard 1995,

Bierregaard & Stouffer 1997, Renjifo 1999, Graham & Blake 2001). The potential

benefits of such a strategy are illustrated by one of my study areas, Abejorral (Colombian

Central Andes, Table 3.1), where despite of having a deforested landscape (< 28% of

forest cover remaining), supported >70% of all migrant species in the matrix dominated

by agroforestry systems moderately connected by riverine forests (pers. obs.).

Mixed-species flocks

Composition and size of mixed-species flocks were sensitive to landscape and

habitat features, particularly associated with reduction of forest cover within 1 km2.

When percentage of forest cover was reduced by half, ∼50% fewer species occurred in

mixed-species flocks in all but one habitat type (mature forest). Likewise, Maldonado-

Coelho & Marini (2001, 2004) and Tellería et al. (2001) reported declining species

richness and size of mixed-species flocks as size of rain forest fragments decreased. My

study further showed that the relationship between the reduction of regional forest cover

and the decline in richness of mixed-species flocks was sharper in more-disturbed habitat

such as successional and silvopastures (Fig. 3.12). This decline in richness in flocks was

mostly due to the decline or local disappearance of sensitive bird species of particular

habitat requirements (Tellería et al. 2001) with decrease in regional forest cover and

reduction in habitat complexity. For example, bark insectivores (Lepidocolaptes spp.),

68

ground-dweller flocking bird species (e.g. Golden-crowned Warbler and Three-stripped

Warbler), several brush-finches (Genus Atlapetes and Buarremon) and some migrants

such as Canada Warbler, among others, were absent from habitats with degraded

understory or reduced tree component. However, richness of flocks was greater in

secondary forest and agroforestry/silvopastoral habitats than mature forest, but

composition of flocks in the former habitats was most associated with generalists bird

species (e.g. several Tanagers such as Thraupis spp. and Hemithraupis spp.) as well as

several Neotropical migratory parulids (e.g. Dendroica spp. and Vermivora spp.), which

were virtually absent from mature forest.

Although I did not test mechanisms driving the observed patterns, other studies

show that changes in forest cover and habitat structure can affect resource availability

and the diversity of microhabitats (i.e. reduction in foraging strata), directly affecting the

flocking species pool (Robinson & Holmes 1982, Develey & Peres 2000, Telleria et al.

2001, Lee et al. 2005). The species pool, in turn, influences flocks, as demonstrated by

Latta & Wunderle (1996), who found that richness of mixed-species flocks in Hispaniola

was limited primarily by local species richness. Similarly, Maldonado-Coehlo & Marini

(2004) argued that the decrease in species richness of flocks was due to a reduced species

pool in fragments. In my study areas, I found a strong positive association between

richness of mixed-species flocks with both regional avian richness and Neotropical

migrant richness. Thus, low flock richness might stem from an impoverished regional

species pool of both resident a migratory birds. Reduction in the amount of regional

forest cover and an impoverished species pool may also limit the propensity of species to

flock, since they were more consistently found in areas with forest cover above ~ 20%.

69

Several studies in the Neotropical lowlands have shown that flocks tend to disintegrate in

forest fragments below a critical size, mainly due to the limitation to support a flock

territory or the extinction of important nuclear species (Maldonado-Coelho & Marini

2004, Stouffer & Bierregaard 1995). Non-systematic observations on several Andean

flocks in our study sites showed that they exhibit, to some extent, territoriality. In

addition, several nuclear bird species (e.g. Myioborus spp., Hylophilus spp. and

Chlorospingus spp.) were virtually absent from highly deforested habitats (e.g. < 10-15%

forest cover within 1-km2). Therefore, loss of regional forest cover may limit the

presence of important nuclear species key for flock formation.

Conservation implications

Overall, my research shows that Neotropical migrants and mixed-species flocks

were influenced by environmental factors operating across multiple spatial scales, and

that the importance of any particular environmental attribute changes with landscape

context and habitat type. As a whole, (1) regions with lower forest cover seemed less able

to support mixed species flocks, (2) habitat complexity tended to be most important (i.e.,

steeper slope) to flock and migrant attributes in deforested landscapes, and (3) high

structural complexity may partially compensate for some of the negative effects of

deforestation, as suggested by the converging trend lines with increasing hábitat

complexity. Nevertheless, while forested habitats continue to play a key role in

providing suitable habitat for both migratory birds and flocks in fragmented and human-

dominated landscapes, my research cautions that local habitat management or restoration

efforts aimed at enhancing conditions for migratory and flocking birds should consider

the strong interactions with environmental attributes at other spatial scales. In particular,

70

local conservation actions should carefully consider not only the type of habitat or

ecosystem but also the amount of regional forest cover in the surrounding landscape

matrix.

My research provides additional evidence that shade coffee can provide an

important habitat to overwintering migrants and generalist resident bird species (e.g.

Perfecto et al. 1996, Greenberg et al. 1997, Wunderle & Latta 1998, 2000, Johnson et al.

2006, Bakermans et al. 2009). Nevertheless, conservationists must be careful not to

judge value solely in terms of richness since given that (1) sensitive species, including

regional endemics, often are poorly represented in agroforestry systems and (2) managed

lands may fail to perform other ecosystem services (Tejeda-Cruz & Sutherland 2004,

Johnson et al. 2006). Consequently, agroforestry habitats should not be viewed as

surrogates for mature or primary forests.

Additional work is needed to develop landscape and habitat-specific guidelines

for management and ecological restoration. Future studies on Neotropical migrants

should explicitly incorporate multiple scales and elucidate underlying ecological

mechanisms. Given the scale-dependent nature of habitat selection (e.g. Hutto 1985,

Kelly & Hutto 2005, Deppe & Rotenberry 2008), studies at different spatial scales in the

Andes are needed to understand patterns of habitat use by montane forest birds, including

Neotropical migrants, and to identify effective conservation strategies for fragmented

environments.

71

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84

Table 3.1. Site characteristics for 11 different landscapes on the Colombian, Ecuadorian

and Peruvian Andes. Values presented are mean ± SD.

Correlation with

Habitat variable Mean ± SD PC1 PC2

Tree density (stems ha-1) 320.67 ± 197.87 0.973** -0.184

Shrub density 19.01 ± 11.8 0.904** -0.124

Canopy cover (%) 52.33 ± 16.17 0.829** 0.491

Ground cover (%) 54.39 ± 21.81 0.68* 0.708*

Basal area (m2 ha-1) 21.6 ± 22.67 0.824** -0.352

Canopy height (m) 10.33 ± 4.45 0.923** -0.332

Eigenvalue 4.44 1.03

Cumulative variance explained (%) 74.06 91.18

85

Table 3.2. Pearson’s correlations for 6 structural variables derived from 487 vegetation

plots in 11 regions in the Andes. *P < 0.05; **P < 0.01.

Tree density

(stems ha-1)

Shrub density Canopy cover

(%)

Ground cover

(%)

Basal area

(m2 ha-1)

Shrub density 0.599**

Canopy cover (%) 0.461** 0.161

Ground cover (m) 0.223 0.384* 0.548**

Basal area (m2 ha-1) 0.579** 0.366* 0.202 0.039

Canopy Height (m) 0.767** 0.457** 0.433** 0.322* 0.8**

86

Table 3.3. Set of candidate models to test for relationships between flocks and migrants

attributes and environmental effects. K represents number of parameters to be estimated.

Hypothesis Candidate model K Ecological rationale

Null model Null (Ø) 1 No relationship. Predictor variables do not explain variation any better than a constant.

Deforestation Forest cover within 1 km2 pixel

2 Forested landscapes improve connectivity, reduce area and edge effects, and reduce human-associated disturbances.

Habitat patch type Habitat types 5 Habitat types differ in the quality and type of resources provided to different species.

Local structural complexity

Structural complexity of local habitat

2 Increasing levels of structural complexity, both vertically (e.g., canopy height) and horizontally (e.g., shrub density), promote greater number of species and individuals.

Deforestation and habitat type

Forest cover + Habitat type

6 Species and flocks are sensitive both to amounts of forest cover in the landscape and type of habitat patch.

Habitat type and local structural complexity

Habitat type + local structure

6 Species and flocks are sensitive to both habitat type and local structural complexity.

Interaction- deforestation and habitat in the landscape

Forest cover + Habitat type + interaction

10 The effect of deforestation (i.e. percentage of forest cover) depends upon the type and amount of habitat in the landscape.

Interaction-Habitat type and local structural complexity

Habitat type + local structure + interaction

10 Sensitivity to deforestation depends on the structural complexity of the habitat.

Interaction-deforestation and local structural complexity

Forest cover + Local structure + interaction

4 Regional forest cover is associated with local habitat structure.

Deforestation-habitat type and local structural complexity relationships

Habitat type + local structure + forest cover

7 Multi-scale effects of predictor variables on attributes of mixed-species flocks and migrants.

Interaction- deforestation-Habitat type and local structural complexity relationships

Habitat type + local structure + forest cover + interactions

20 Landscape context affects relationships with habitat type and structure.

87

Table 3.4.Correlation of habitat variables with derived Principal Components Analysis

scores, eigenvalue and cumulative variance explained in 11 regions in the Northern and

Central Andes. *P < 0.05; **P < 0.01.

Correlation with

Habitat variable Mean ± SD PC1 PC2

Tree density (stems ha-1) 320.67 ± 197.87 0.973** -0.184

Shrub density 19.01 ± 11.8 0.904** -0.124

Canopy cover (%) 52.33 ± 16.17 0.829** 0.491

Ground cover (%) 54.39 ± 21.81 0.68* 0.708*

Basal area (m2 ha-1) 21.6 ± 22.67 0.824** -0.352

Canopy height (m) 10.33 ± 4.45 0.923** -0.332

Eigenvalue 4.44 1.03

Cumulative variance explained (%) 74.06 91.18

88

Table 3.5. Fifteen most common bird species in 186 mixed-species flocks in the Andes.

The metric represents the percentage of flocks that included the listed species.

Species

Occurrence in mixed-

species flocks (%)

Blackburnian Warbler Dendroica fusca 0.43

Blue-gray Tanager Thraupis episcopus 0.35

Golden-faced Tyrannulet Zymmerius chrysops 0.26

Slate-throated Whitestart Myioborus miniatus 0.25

Scrub Tanager Tangara vitriolina 0.24

Bay-headed Tanager Tangara gyrola 0.23

Tennessee Warbler Vermivora peregrina 0.22

Blue-necked Tanager Tangara cyanicollis 0.18

Golden-crowned Warbler Basileuterus culicivorus 0.14

Bananaquit Coereba flaveola 0.14

Cerulean Warbler Dendroica cerulea 0.13

Tropical Parula Parula pitiayumi 0.13

Golden-fronted Whitestart Myioborus ornatus 0.12

Canada Warbler Wilsonia canadensis 0.11

Golden Tanager Tangara arthus 0.11

89

Table 3.6. Summary statistics for MRPP results of comparisons of average within-group

distance of mixed-species flocks across five different habitats in the Andes. T represents

the test statistic describing the separation between habitats (the more negative, the

stronger the separation); P represents the probability of the expected delta (the weighted

mean within-group distance) calculated for all possible partitions of the data being as

small or smaller than the observed delta; and A represents the chance-corrected within

group agreement describing the within-group homogeneity as compared to random

expectation (e.g. A = 0 when heterogeneity within groups equals expectation by chance;

MacCune and Grace 2002).

Habitat (sample size) Average within-group distance (ranked Sorenson

distance)

T P A

Successional (23) 0.933

Secondary forest (81) 0.916

Mature forest (21) 0.901

Silvopasture (13) 0.895

Shade coffee (48) 0.84

All (186 flocks) -12.095 0.000 0.020

Multiple pairwise comparisons

Shade vs. mature forest -15.094 0.037 0.000

Shade vs. secondary forest -10.035 0.013 0.000

Secondary vs. mature forest -9.198 0.014 0.000

Pastures w/trees vs. mature forest -5.548 0.021 0.000

Successional vs. mature forest -4.975 0.028 0.000

Shade coffee vs. pastures w/trees -3.830 0.009 0.002

Secondary forest vs. successional -1.815 0.003 0.054

Shade coffee vs. successional -0.978 0.003 0.158

Pastures w/trees vs. successional -0.767 0.004 0.208

Secondary forest vs. silvopasture -0.589 0.001 0.245

90

Table 3.7. Regression models to relate flock attributes and environmental variables.

Model selection was based on biased-adjusted Akaike’s Information Criterion (AICc).

Statistics include the number of estimated parameters (K), the second-order Akaike

Information Criterion (AICc), AIC differences (ΔAICc), and Akaike weights (wi).

Models are listed in descending order of wi. Models with ΔAICc < 2 are listed.

Model K AICc ΔAICc wi

Flock richness

Habitat + local structure + forest cover

+ interactions 20 191.587 0.000 0.985

Flock size

Habitat + local structure + Habitat x

local structure 10 102.538 0.000 0.485

Habitat + local structure + forest cover

+ interactions 20 103.057 0.518 0.374

Flock encounter rate

Habitat + forest cover + interactions 10 21.888 0.000 0.441

Local structure + forest cover +

interactions 4 23.244 1.356 0.224

91

Table 3.8. Regression models relating environmental variables and richness and

abundance of Neotropical migrants detected on transects. Model selection was based on

biased-adjusted Akaike’s Information Criterion (AICc). Statistics include the number of

estimated parameters (K), the second-order Akaike information Criterion (AICc), AIC

differences (ΔAICc), and Akaike weights (wi). Models are listed in descending order of

wi. Only models with ΔAICc < 2 are listed.

Model K AICc ΔAICc wi

Neotropical migrants richness

NTMB richness = local structure + forest cover + local

structure*forest cover 4 91.047 0.000 0.533

NTMB richness = habitat type 5 92.693 1.646 0.234

Neotropical migrants abundance

NTMB abundance = local structure + forest cover + local

structure*forest cover 4 207.15 0.000 0.481

NTMB abundance = habitat type 5 208.41 1.26 0.256

92

Table 3.9. Summary of main relationships of forest cover and habitat complexity on

flocks and Neotropical migrant attributes in different habitat types.

Attribute Forest cover Habitat complexity

Flock richness Successional habitat + + Silvopasture + + Shade coffee + 0 Secondary forest + + Mature forest 0 - Flock size Successional habitat + + Silvopasture + + Shade coffee 0 - Secondary forest + + Mature forest - - Flock encounter rate Successional habitat 0 0 Silvopasture 0 0 Shade coffee + 0 Secondary forest 0 0 Mature forest 0 0 NTMB richness on transects Successional habitat 0 0 Silvopasture 0 0 Shade coffee 0 + Secondary forest 0 0 Mature forest 0 0 NTMB abundance on transects Successional habitat 0 0 Silvopasture 0 + Shade coffee + + Secondary forest 0 0 Mature forest 0 0

93

Figure 3.1. Five habitat types identified during surveys in the Andes. From the top left to

the bottom, clockwise: mature forest, secondary forest, shade coffee, pastures with

isolated trees and successional.

94

Figure 3.2. Eleven surveyed locations in the Northern and Central Andes. Numbers

represent 1-km2 pixel sites visited within each region. From north to south: Aguachica,

San José de la Montaña, Yariguies, Chicamocha, Abejorral, Paya, Ibague, Rosas, Patia,

Sangay National Park and Chingozales.

95

Figure 3.3. Example of field sampling design for allocating 100 m line transects within 1-

km2 pixels to survey bird fauna and to locate temporary vegetation plots in the Andes.

96

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Figure 3.7. Species richness of Neotropical-Nearctic migrants increased with flock

richness and flock encounter rate (i.e. Number of flocks encountered per hour of survey).

Lineal models were constructed accounting for flock size.

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101

Figu

re 3

.8b.

Geo

grap

hic

dist

ribut

ion

of N

eotro

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l-Nea

rctic

mig

rant

s in

the

And

es a

long

ele

vatio

n an

d lo

ngitu

de g

radi

ents

.

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ea

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nn

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Trin

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102

Figure 3.9. Sample-based smoothed accumulation curves of species in mixed-species

flocks among five habitats. Arrow indicates maximum rarefaction point in the number of

individuals achieved for all the habitats.

0

20

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60

80

100

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0 100 200 300 400 500 600 700 800 900

No.

of s

peci

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mix

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peci

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lock

s

No. of individuals

shaded monoculturemature forestpastures with isolated treessecondary forestsuccessional

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Figure 3.10. Sample-based smoothed accumulation curves of Neotropical-Nearctic

migrant species assisting mixed-species flocks among five habitats. Arrow indicates

maximum rarefaction point in the number of individuals achieved for all the habitats.

0

2

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of N

TMB

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in m

ixed

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floc

ks

No. of individuals

shaded monoculturemature forestpastures with isolated treessecondary forestsuccessional

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Figure 3.11. NMS ordination joint plot of sample scores (i.e. mixed-species flocks) in

species space on the first and third NMS axes for the two most contrasting habitats, shade

coffee (open circles) and mature forest (crosses).

-1

-0.5

0

0.5

1

-1 -0.5 0 0.5 1

NM

S 3

NMS 1

105

Figure 3.12. Relationship between flock species richness and increasing percentage of

forest cover within 1-km2 pixels in the Andes, 2007-2010. Graphs constructed using top-

ranked models simulating a gradient of forest cover. Dotted lines along major line

represent standard errors for the predictions.

0

2

4

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Floc

k ric

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Forest cover (%)

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k ric

hnes

s

Forest cover (%)

silvopastures

shade coffee

successional

secondary forest

mature forest

106

Figure 3.13. Relationship between flock size and increasing percentage of forest cover

within 1-km2 pixels in the Andes, 2007-2010. Graphs constructed using top-ranked

models simulating a gradient of forest cover. Dotted lines along major line represent

standard errors for the predictions.

0

5

10

15

20

25

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Floc

k ab

unda

nce

Forest cover (%)

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Floc

k ab

unda

nce

Forest cover (%)

silvopastures

shade coffee

successional

secondary forest

mature forest

107

Figure 3.14. Relationship between flock encounter rate per hour and increasing

percentage of forest cover within 1-km2 pixels in the Andes, 2007-2010. Graphs

constructed using top-ranked models simulating a gradient of forest cover. Dotted lines

along major line represent standard errors for the predictions.

-1

-0.5

0

0.5

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1.5

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0 20 40 60 80Floc

k en

coun

ter r

ate

Forest cover (%)-1

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Forest cover (%)

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-0.5

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0 20 40 60 80Floc

k en

coun

ter r

ate

Forest cover (%)

silvopastures

shade coffee

successional

secondary forest

mature forest

108

Figure 3.15. Relationship between richness of flocks and habitat structure in the Andes,

2007-2010. Graphs constructed using top-ranked models simulating a gradient of habitat


high regional forest cover (61.9%). Blue line: low regional forest cover (19.6%).

-4

-2

0

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-3 -2 -1 0 1 2 3

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k ric

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Gradient of habitat complexity

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silvopastures

shade coffee

successional

secondary forest

mature forest

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Figure 3.16. Relationship between flock size and habitat structure in the Andes, 2007-

2010. Graphs constructed using top-ranked models simulating a gradient of habitat



0

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Floc

k si

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silvopastures

shade coffee

successional

secondary forest

mature forest

110

Figure 3.17. Relationship between flock encounter rate per hour and habitat structure in

the Andes, 2007-2010. Graphs constructed using top-ranked models simulating a gradient

of habitat complexity. Dotted lines along major line represent standard errors for the



-2

-1.5

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Gradient of habitat complexity -2

-1.5

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Gradient of habitat complexity-2

-1.5

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ock

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silvopastures

shade coffee

successional

secondary forest

mature forest

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Figure 3.18. Association between richness of Neotropical migrant birds recorded on



Dotted lines along major line represent standard errors for the predictions.

-1

-0.5

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0.5

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1.5

0 20 40 60 80

Neo

trop

ical

mig

rant

rich

ness

Forest cover (%)-1

-0.5

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Neo

trop

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mig

rant

rich

ness

Forest cover (%)

-1

-0.5

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Neo

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mig

rant

rich

ness

Forest cover (%)-1

-0.5

0

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1.5

0 20 40 60 80N

eotr

opic

al m

igra

nt ri

chne

ss

Forest cover (%)

-1

-0.5

0

0.5

1

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0 20 40 60 80

Neo

trop

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mig

rant

rich

ness

Forest cover (%)

silvopastures

shade coffee

successional

secondary forest

mature forest

112

Figure 3.19. Association between abundance of Neotropical migrant birds recorded on



Dotted lines along major line represent standard errors for the predictions

-0.5

0.5

1.5

2.5

3.5

4.5

0 20 40 60 80

Neo

trop

ical

mig

rant

abu

ndan

ce

Forest cover (%)-0.5

0.5

1.5

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4.5

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Neo

trop

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mig

rant

abu

ndan

ce

Forest cover (%)

-0.5

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Neo

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mig

rant

abu

ndan

ce

Forest cover (%)-0.5

0.5

1.5

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3.5

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Neo

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mig

rant

abu

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ce

Forest cover (%)

-0.5

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Neo

trop

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mig

rant

abu

ndan

ce

Forest cover (%)

silvopastures

shade coffee

successional

secondary forest

mature forest

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Figure 3.20. Association between richness of Neotropical migrant birds and local habitat

structure in the Andes. Graphs constructed using top-ranked models simulating a gradient

of habitat structure. Dotted lines along major line represent standard errors for the



-1

-0.5

0

0.5

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ness


-0.5

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rant

rich

ness


silvopastures

shade coffee

successional

secondary forest

mature forest

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Figure 3.21. Association between abundance of Neotropical migrant birds and local

habitat structure in the Andes. Graphs constructed using top-ranked models simulating a

gradient of habitat structure. Dotted lines along major line represent standard errors for

the predictions. Dotted lines along major line represent SE for the predictions. Gray line:


-1

0

1

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-3 -2 -1 0 1 2 3

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trop

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mig

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silvopastures

shade coffee

successional

secondary forest

mature forest

115

4 PATTERNS OF MASS CHANGE IN WINTERING NEOTROPICAL-NEARCTIC

MIGRATORY BIRDS IN SHADED MONOCULTURES IN THE ANDES

Abstract. Despite the widely accepted idea that shaded monocultures are valuable

habitats for Neotropical migrants in disturbed landscapes, little empirical evidence is

available in relation to the quality of this habitat for Neotropical-Nearctic migratory birds

in the Andes. I evaluated the suitability of shaded monocultures for overwintering

Neotropical-Nearctic migratory birds by examining diurnal and seasonal variation in

body condition of migrants in shaded monocultures in the Colombian Andes.

Futhermore, because Neotropical-Nearctic migrants frequently join mixed-species flocks

during the nonbreeding season, I also evaluated the extent to which body condition

changed with flocking behavior. During October-April 2008-2009 and 2009-2010, I mist-

netted 8 species of Neotropical-Nearctic migrants in shaded monocultures in the

Colombian Andes. Body condition improved throughout the day for Cerulean Warbler,

Blackburnian Warbler, Tennessee Warbler, and especially Canada Warbler. Similarly,

body condition improved across the season for Tennessee Warbler, Rose-breasted

Grosbeak, and Summer Tanager. Neither body condition nor seasonal change in body

condition differed between flocking and solitary individuals for most of the migratory

species evaluated. However, Cerulean and Blackburnian Warblers showed stronger

improvements in condition when foraging solitary than in flocks. My results provided

116

additional evidence that several common Neotropical migrants, including species of

conservation concern such as Cerulean Warbler, may improve their body condition in

agroforestry systems of shaded monocultures.

Keywords: shaded monocultures, agroforestry systems, foraging enhancement,

flocking behavior, body condition, migratory birds, Colombia.

Introduction

Population declines in Neotropical-Nearctic migratory birds have been widely

documented during the breeding, migration and winter periods (Robbins et al. 1989,

Hussell et al. 1992, Faaborg & Arendt 1992, Faaborg et al. 2010). While most studies

focus on impacts of breeding season events , recent work demonstrates that habitat

quality experienced by birds during the non-breeding season may contribute strongly to

population limitation of Neotropical migrants (Holmes et al. 1989, Sliwa and Sherry

1992, Marra et al. 1993, Marra and Holmes 2001, Sherry et al. 2005). The availability of

high quality non-breeding habitat continues to be reduced byforest loss and conversion of

undisturbed forests to other land uses (Hutto 1988, Robbins et al. 1989, Terborgh 1989,

Petit et al. 1995). Although agroforestry systems also represent a form of land

conversion and intensification, previous studies suggest that agroforestry systems, in

particular shade coffee, might be beneficial for migratory birds and may represent a

valuable habitat by supporting high levels of biodiversity (Perfecto et al. 1996, Greenberg

et al. 2000, Perfecto et al. 2003, Komar 2006). The ecological value of agroforestry

systems to support migratory birds during the nonbreeding period usually has been

evaluated using measures such as richness, abundance and survival estimates (Wunderle

117

& Latta 1996, Johnson et al. 2006). However, these measures can be impractical and

misleading indicators of habitat quality because of the large amount of time and large

datasets needed (Johnson et al. 2006). These disadvantages have encouraged the use of

other metrics, particularly body condition (i.e. body mass corrected for body size) and its

patterns of overwinter change (Strong & Sherry 2001, Marra & Holmes 2001). Body

condition of migrants in wintering grounds has shown to be directly affected by habitat

quality and food availability (e.g. Strong & Sherry 2000). Improvement of body

condition is known to be related to annual survival (Sillet et al. 2000) and potentially

associated with carry-over effects to future reproductive success (Marra et al. 1998).Our

understanding of how different overwintering habitats (e.g. shaded agriculture) may

affect body condition remains limited (Strong & Sherry 2000, Wunderle & Latta 2000,

Bakermans et al. 2009). For example, despite the relevance of body condition as a proxy

for evaluating habitat quality of shade coffee for Neotropical migrants, only one recent

study conducted in the Venezuelan Andes showed that migrants can improve their body

condition while wintering in shade coffee (Bakermans et al. 2009).

Not only is body condition influenced by food availability (Strong and Sherry

2000), but other factors including social behavior (i.e. association in mixed species

flocks), might also influence body condition given that participating in flocks may incur a

variety of benefits (e.g.. enhancing foraging ability; Cody 1971, Waite & Grubb 1988,

Sridhar et al. 2009) and costs (e.g. intraspecific and interspecific competition for food

resources; Terborgh 1990, Greenberg 2000, Polo & Bautista 2002, Lange & Leimar

2004). Since a large proportion of Neotropical migratory birds join mixed species flocks

while in their wintering grounds (Moynihan 1962, Powell 1985, Robbins et al. 1989,

118

Hutto 1994, Rappole 1995, Latta & Wunderle 1996), including some species of

conservation concern such as the Cerulean Warbler (BirdLife International 2008),

understanding the ways in which flock participation may influence condition of

migratory birds during the nonbreeding period, may provide insight about limiting factors

affecting the overwinter performance of migratory birds. This knowledge is especially

important today, as montane habitas in the Neotropical Andes have been extensively

deforested and fragmented.

In this study, I evaluated (1) the suitability of shaded monocultures for

overwintering Neotropical-Nearctic migratory birds by examining diurnal and seasonal

variation in body condition and (2) the extent to which diurnal and seasonal variation in

body condition was associated with flocking behavior of Neotropical-Nearctic migratory

birds wintering in shaded monocultures.


Study area

Study sites were established in Southwestern Antioquia department, Colombia, in

the municipalities of Jerico (Cultivares farm: 5o 48’ N, 75o 48’ W. Western Andes),

Fredonia (Gualanday farm; 5o 56’ N, 75o 39’ W. Central Andes) and Tamesis (La

Cumbre farm; 5o 45’ N, 75o 42’ W. Western Andes; Fig. 1). Elevation ranged from 1450

to 1650 m. In all locations, the primary habitat type was shaded monoculture of coffee

(Coffea arabica; Rubiaceae) and cardamom (Elettaria cardamomum; Zingiberaceae).

119

Common shading trees included Inga spp. (Mimosaceae), Cordia alliodora

(Boraginaceae), and Persea spp. (Lauraceae).

Bird sampling

Migrants were captured in the three study sites from October to March during the

wintering seasons (October to March) of 2008-2009 and 2009-2010, using ten standard

nylon mist nets (12 m x 2.5 m, 36 mm mesh), deployed not only horizontally (i.e. ground

nets) but vertically (i.e. ~ 1-10 m height) by using a pulley system. Each site was visited

three times every season. In order to improve capture rate, three banding stations were

established within each site and separated by > 200 m. Mist nets were arranged using a

combination of ground and canopy nets in order to capture all the birds that passed

through a particular location. Nets were checked every 30 to 45 minutes.

Each station was run for 4 days for a total of 36 mist-netting days per wintering

season per location (3 stations per site x 4 days per visit x 3 visits per year). Mist nets

were run continuously 7-10 hours per day, opened within half an hour after sunrise,

typically between ∼ 6:30 h and ∼16:30 h. Captured birds were banded with numbered

aluminum leg bands and sexed and aged when possible by external characters and degree

of skull of ossification. Unflattened wing chord and tail lengths were measured using a

ruler (± 1 mm). Birds were weighed using a digital scale with precision ± 0.1 g. All birds

were examined for body molt with a possible range from 0 (none) to 4 (heavy), flight

feather molt in terms of symmetry and flight feather wear.

I used several indicators to determine whether a bird was considered captured

while foraging in a flock or solitary. First, mist nets were usually observed with

120

binoculars from a distance. This allowed us to determine if a flock hadmoved through the

area. Second, as our research in these farms spans several years, our knowledge of the

local flocking systems, in particular routes and timing of movement, is fairly good. Due

to this understanding in the behavior of the flocks and the species that join them, we

could anticipate and follow flock movements while watching nets.When a flock was

passing through our arrangement of canopy and ground mist nets, we were generally

confident that caught birds were flocking birds. Likewise, when no flocks were observed

either moving toward the nets or falling in the nets, caught birds were considered solitary

foragers. Finally, the number and type of bird species captured per net run was also

sometimes used as complementary criteria. Because we stacked nets and constructed a

pulley system to capture birds throughout the vertical strata (~1.0-10 m), we were

successful intercepting flocks and nearly always captured multiple flock participants.

Consequently, a bird captured alone or with one other bird in the same net or in the

closest net during the same net run was considered solitary. This pattern was confirmed

by our years of experience banding birds at these sites.

Body condition index

To assess physical condition of birds, I calculated a body condition index that

accounts for structural size. Body condition represents a good and useful proxy for

assessing habitat quality and its effects on individuals (Brown 1996, Johnson 2007). The

body condition metric accounted for body frame (structural) size by first performing a

principal components analysis (PCA) on wing chord and tail length. I then regressed

body mass against PC1 scores and the residuals were used as an index of body condition

(Wunderle & Latta 2000). The extent to which the predicted values deviated from

121

expected mass given a certain body size (i.e., residuals) indicated whether the bird was in

good (i.e., residual above the regression line) or poor (i.e. residual below) body condition.

I also tested the degree of association between body size (i.e. PC1) and flocking behavior

(e.g. smaller birds tended to join flocks more than large birds; Thiollay & Jullien 1998).

Statistical analysis

I used data only from first captured individuals (i.e., recaptures were excluded),

and selected eight Neotropical-Nearctic migratory species based on sample size (> 25

captures during the two-year period of study; Table 4.1) and regularity in flocks in my

study sites: Cerulean Warbler (Dendroica cerulea), Blackburnian Warbler (Dendroica

fusca), Tennessee Warbler (Vermivora peregrina), Canada Warbler (Wilsonia

Canadensis), Rose-breasted Grosbeak (Pheucticus ludovicianus), Red-eyed Vireo (Vireo

olivaceus), Summer Tanager (Piranga rubra), and Empidonax flycatchers (Empidonax

spp.).

I first assessed correlations between body condition and time of day, day of

season, sex, age, body molt and season. Because mean body conditions did not differ

among the three study locations (Jerico, Tamesis and Fredonia; P > 0.1), data from the

three locations were pooled together for analyses. Similarly, there was no a significant

relationship between body condition and sex, age, body molt or year for any of the

studied species (all P > 0.1; Appendix J). To further evaluate if flock and solitary samples

were comparable, I tested for differences between solitary and flocking birds for sex, age

and season. Similar sex ratios (i.e., proportions of males and females) were captured for

solitary and flocking categories for Cerulean Warbler (χ2 = 0.14, df = 1, P = 0.71),

Blackburnian Warbler (χ2 = 1.51, df = 1, P = 0.22), Tennessee Warbler (χ2 = 0.001, df =

122

1, P = 0.97), Canada Warbler (χ2 = 0.09, df = 1, P = 0.76), Rose-breasted Grosbeak (χ2 =

0.23, df = 1, P = 0.63) and Summer Tanager (χ2 = 0.001, df = 1, P = 0.98). Age

distributions (i.e. adult vs. juvenile) also were similar for solitary and flocking categories

across the same migratory species (χ2 < 2.68, df = 1, P > 0.1). Cerulean Warblers were

captured marginally more frequently in flocks than solitary in the wintering season of

2009-2010 than in the previous season (χ2 = 3.57, df = 1, P = 0.06), whereas other species

were evenly captured in flock vs. solitary in both seasons (χ2 < 3.26, df = 1, P > 0.1).

Because I also found no differences in body condition based on sex, age, molt, and year, I

pooled the data for subsequent analyses.

To determine if shaded monocultures provided habitat that allowed migratory

birds to gain mass, I ran regression models separately for each species to test

relationships between (1) body condition and time of day (i.e., trends in daily mass

change) and (2) body condition and day of season. I assessed the effect of social status

(i.e. flock and solitary) on daily and seasonal changes (hour of day and day of season,

respectively) in body condition separately for each species using linear regression

analysis. Previous studies have shown that these temporal variables can strongly affect

body condition (e.g. Carlisle et al. 2005, Seewagen & Slayton 2008). I excluded

Empidonax flycatchers from the seasonal analysis (i.e. relationship of body condition by

social status and day of the season), since no birds were captured in flocks later in the

season (∼after day 90). I constructed linear regression models for (1) hour of day and (2)

day of the season as predictors, and I incorporated social status as an indicator variable.

The models were run as,

123

𝐵𝐶𝐼 = 𝛽0 + 𝛽1 × ℎ𝑜𝑢𝑟 𝑜𝑓 𝑑𝑎𝑦 + 𝛽2 × 𝑓𝑙𝑜𝑐𝑘 𝑠𝑡𝑎𝑡𝑢𝑠 + 𝛽3 × ℎ𝑜𝑢𝑟 𝑜𝑓 𝑑𝑎𝑦 × 𝑓𝑙𝑜𝑐𝑘 𝑠𝑡𝑎𝑡𝑢𝑠

𝐵𝐶𝐼 = 𝛽0 + 𝛽1 × 𝑑𝑎𝑦 𝑜𝑓 𝑠𝑒𝑎𝑠𝑜𝑛 + 𝛽2 × 𝑓𝑙𝑜𝑐𝑘 𝑠𝑡𝑎𝑡𝑢𝑠 + 𝛽3 × 𝑑𝑎𝑦 𝑜𝑓 𝑠𝑒𝑎𝑠𝑜𝑛 × 𝑓𝑙𝑜𝑐𝑘 𝑠𝑡𝑎𝑡𝑢𝑠

I finally assessed whether the variances of the body condition of birds captured in

flock and solitary were significantly different (e.g. birds in flocks present less variation in

their body condition throughout the season than birds foraging solitary) using an F-test

for the ratio of variances which compares standard deviations. Data for each migrant

were checked for normality and homocedasticity. All statistical analyses were conducted

using STATGRAPHICS Centurion XV (Statpoint 2005).

Results

I captured and recorded complete measurements of 624 new individuals of 8

Neotropical migrant species in shaded monocultures from the wintering seasons 2008-

2009 and 2009-2010 (Table 4.1). After adjusting for effort, the average capture rate of

Neotropical-Nearctic migratory species in shaded monocultures in southwestern

Antioquia was 4.85 birds/100 net hours. Weights varied from 7.59 g (Tennessee Warbler)

to 56.5 g (Rose-breasted Grosbeak), with Cerulean Warbler averaging the minimum

weight (8.86 ± 0.54 g, N = 54) and Rose-breasted Grosbeak averaging the maximum

(43.68 ± 4.95 g, N = 78; Table 4.1). Most body condition scores were negative regardless

of social status (Table 4.2). For the 8 migrant species, the first principal component (PC1)

explained 96.3% of the variation in linear measurements and both wing and tail length

loaded positively with PC1 (r = 0.98, P < 0.001). I found no evident capture bias in body

frame (i.e. PC1) and flocking status (all P > 0.1 for all species; Table 4.3).

124

Temporal changes in body condition in shade monocultures

Four of eight migratory species showed evidence that body condition improved

throughout the day – Cerulean Warbler (β = 0.001 ± 0.0004, t = 2.43, P = 0.02),

Blackburnian Warbler (β = 0.001 ± 0.0003, t = 3.35, P = 0.001), Tennessee Warbler (β =

0.001 ± 0.0004, t = 3.57, P < 0.01), and Canada Warbler (β = 0.002 ± 0.0003, t = 5.14, P

< 0.01, Table 4.4). There were no significant associations between body condition and

time of day for Rose-breasted Grosbeak, Red-eyed Vireo, Summer Tanager and

Empidonax flycatchers (P > 0.1, Table 4.4).

Body condition improved over the non-breeding season for Tennessee Warbler (β

= 0.005 ± 0.0015, t = 3.19, P = 0.002), Rose-breasted Grosbeak (β = 0.023 ± 0.0062, t =

3.7, P < 0.01), and Summer Tanager (β = 0.021 ± 0.0067, t = 3.07, P < 0.01; Table 4.4).

Associations between body condition and flocking behavior

Irrespective of flocking behavior, birds were generally in poor body condition

early in the morning (Fig. 4.2), but only Cerulean Warbler showed significantly different

patterns of diurnal changes in body condition depending on social status. Ceruleans that

were captured when foraging solitarily showed increasing measures of body condition

throughout the day than individuals captured while participating in flocks (β solitary:

0.0023 ± 0.001; β flocks: 0.0002 ± 0.0006, P = 0.05, Table 4.5; Fig. 4.2). Daily changes

in body condition were not significantly related to social status for other species (P >

0.01, Table 4.5).

Differences in daily changes in body condition between individuals in flock or

solitary were not associated to sex or age, except for Summer Tanager for which males

125

marginally improved their body condition while foraging in flocks (β = 1.877 ± 4.111)

when compared with females in flocks (β = -2.385 ± 2.066; F4, 46 = 2.17, P = 0.09; β

social status x sex: -1.0207 ± 0.4521, t = 2.26, P = 0.03, Table 4.6).

Seasonal changes in body condition were not significantly related to flocking

behavior for most migratory bird species (P > 0.1; Table 4.7, Fig. 4.3), with the exception

of Blackburnian Warbler, which showed that increasing body condition across the seaon

for birds captured alone (β = 0.044 ± 0.002, P = 0.01) compared to birds captured in

flocks (β = -0.0006 ± 0.0013, P = 0.64, Table 4.7, Fig. 4.3). Differences in seasonal

changes in body condition between individuals in flock or solitary were not associated to

sex or age. I also found no evidence that variances of body condition differed between

flock and solitary foragers (F- test for the ratio of variances, P > 0.08, Table 4.8).

Discussion

Despite the widely accepted idea that shaded monocultures (e.g. shade coffee) are

valuable habitats for Neotropical migrants in disturbed landscapes (Wunderle & Latta

1996, Tejeda-Cruz and Sutherland, Koman 2006), little empirical evidence is available to

demonstrate the quality of this habitat for migratory birds in the Andes (but see

Bakermans et al. 2009). My study revealed that several common Neotropical-Nearctic

migratory species improved body condition both throughout the day and across the

season in shaded monocultures in the Colombia Andes. However, I found no evidence

that participating in mixed-species foraging flocks enhanced overwintering performance.

In fact, for Cerulean and Blackburnian Warblers, the strongest daily and seasonal

126

improvements in condition were associated with solitary foragers, not those individuals

participating in flocks. My findings then suggest that advantages to participating in flocks

are complex and do not simply translate into mass gain.

About half of the Neotropical-Nearctic migratory birds I examined during my

study (4 out of 8 species), improved their body condition as the day progressed

(Cerulean Warbler, Blackburnian Warbler, Tennessee Warbler and Canada Warbler).

Several studies support the linear increase in body masses throughout the day (Moore &

Kerlinger 1987, Moore & Wang 1991, Winker et al. 1992, Dunn 2002, Jones et al. 2002),

and daily increase in body condition is well established theoretically (e.g. McNamara et

al. 1994), empirically (e.g. Lehikoinen 1987, Rogers & Smith 1993, Gosler 1996,

Koivula et al. 2002, Bonter et al. 2007), and by experimental studies (e.g. Ekman & Hake

1990, Bednekoff & Krebs 1995). While this pattern also has been supported for migrating

birds (Dunn 2000, Schaub & Jenni 2000, Delingat et al. 2009), little information is

available in relation to daily body condition gains for migratory birds wintering in the

Neotropics (e.g. Strong & Sherry 2001, Brown & Sherry 2006, Bakermans et al. 2009),

particularly for the Andes. Thus, my data contribute novel information on daily patterns

of body condition improvement for several common migratory birds in shaded

monocultures. Rate of increase of body condition was virtually identical for Cerulean

Warbler, Blackburnian Warbler and Tennessee Warbler (β = 0.001), whereas it was

nearly twice as rapid for Canada Warbler (β = 0.002). The daily improvement of body

condition by the migratory birds in my study may be explained by the constant feeding

activity of these birds throughout the day, particularly after the overnight fasting. Other

127

species (i.e. Summer Tanager, Rose-breasted Grosbeak, Red-eyed Vireo and Empidonax

flycatchers) showed a more stable body condition across the day.

My study also revealed that approximately half of the Neotropical migrants I

tested (Tennessee Warbler, Rose-breasted Grosbeak and Summer Tanager) improved

body condition in shaded monocultures in the Colombian Andes throughout the wintering

season. At present, only one study has provided direct evidences of seasonal

improvement of body condition for three common Neotropical migrants in this habitat in

Venezuela (Bakermans et al. 2009), whereas others have shown stable patterns or

negative changes in the body condition throughout the wintering period (Strong & Sherry

2000, Wunderle & Latta 2000). Similar to Bakermans et al. (2009), nearly 80% of the

migratory birds caught in my study sites had <5% of fat stores in their bodies. Theoretical

and empirical studies have shown that the predictability in food resources in a particular

habitat allows birds to reduced or even eliminate fat storaging (Rappole & Warner 1980,

Strong & Sherry 2000). My study expands on the Venezuela patterns by providing further

evidence of not only seasonal but diurnal gains for several common Neotropical

migrants. This is especially relevant when considering that body condition cannot only

influence the overwinter survival of a bird (e.g. increase risk of mortality by starvation),

but also has carry over effects on the future reproductive period of birds (Marra et al.

1998, Sillet et al. 2000, Strong & Sherry 2000, Norris et al. 2004, Smith & Moore 2005).

Since temporal improvements in body condition have been largely regarded as the most

relevant metric to assess habitat quality for birds in breeding and stopover sites (e.g.

Lilliendahl 2002, Seewagen & Slayton 2008, Delingat et al. 2009, Benson & Bednarz

128

2010), future studies in habitat quality of migrant birds in nonbreeding habitats should

also attempt to include this metric.

My results did not provide compelling evidence that participating in mixed-

species foraging flocks benefited migrants via improvements in body condition, either

over daily or seasonal periods. To the contrary, the only statistically significant patterns

suggested that flock participation reduced mass gain for two species of migratory birds,

Cerulean Warbler and Blackburnian Warbler, both of which show strong flocking

propensities (> 75% of observations, unpubl. data) Interestingly, Cerulean Warbler is a

sensitive species exhibiting strong populations declines (e.g. Hamel 2000). Since several

studies have shown that flocking behavior promotes survival of bird species by reducing

predation pressure on individuals (Thiollay & Jullien 1998, Sridhar et al. 2009), my

results could be showing a behavioral response of maximizing overwinter survival.

Across the nonbreeding season, I found that individuals of Blackburnian Warbler

captured while foraging alone showed positive trends in body condition, in contrast to

patterns exhibited by birds captured while foraging with flocks.

As better body condition was not detected for most flocking vs. solitary

individuals the potential benefit of assisting flocks might be related to other reasons such

as reducing risk of predation. Many studies have shown that animals are subject to a

lower predation risk when in groups than when solitary (Foster & Treherne 1981, Godin

1986, Morgan & Colgan 1987, Jullien & Thiollay 1998, Jullien & Clobert 2000, Zoratto

129

et al. 2009), but competition for food remains one of the major costs of living in groups

(Greenberg 2000, Polo & Bautista 2002). Moreover, theoretical models predict that

joining a group will either have no effect or a negative effect on the net mean foraging

rate of an individual (Ruxton et al. 1995, Krause & Ruxton 2002). This has been

empirically supported by Warkentin & Morton (2000) and Pomara et al. (2003), who

demonstrated that foraging rates varied little or not at all between flocking and solitary

birds for migratory species in their wintering grounds, and joining mixed-species flocks

was more likely associated to reduce predation risk. At the same time, flocking may

confer protection against predation without necessarily improving feeding efficiency

(Rabenold & Christensen 1979, Hutto 1988, Pomara et al. 2003). Thus, solitary foragers

might improve condition at expense of increasing predation risk. Few significant

relationships between body condition and flocking behavior may stem from species-

specific tradeoffs and differences in the relative advantages of flocking. For instance,

some species may use substantially different foraging strategies when solitary than when

flocking (Pomara et al. 2003). These differences, in turn, imply that not necessarily all

participants in flocks accrue benefits and certain species that are joined by other species

might in fact suffer costs (e.g. Zamora et al. 1992, Cimprich & Grubb 1994, Pomara et al.

2003, Faaborg et al. 2010). For example, Jullien & Clobert (2000) studied the survival

rates of birds in several tropical forests, including French Guiana, discriminated by their

flocking propensity (i.e. obligate, facultative and solitary or pairs species). While survival

rates of obligate flock members were significantly higher than estimates for the species

feeding alone or in pairs, survival rates of facultative flock members did not differ from

those of nonflocking species (Jullien & Clobert 2000). In addition, birds may also spread

130

their mass gain more evenly throughout the day when feeding becomes more predictable

(e.g. McNamara & Houston 1990, Houston et al. 1993). An important caveat to my

findings is that I was not able to recapture the same individuals nor to determine the

proportion of time an individual spent foraging solitary versus with a flock throughout

the day. My knowledge of social status is limited to the time of capture. Therefore, the

possibility remains that birds switched strategies (i.e., foraged with flocks or alone)

depending upon their condition and mass gain in the period preceding capture.

My study showed that several common migratory species improved their body condition

in the agroforestry system of shaded monocultures. However, the extent to which this

agricultural system represents high quality habitat requires additional study, especially

comparisons with other types of habitats and the integration of demographic and

behavioral information. Though my study did not include estimations of demographic

parameters, the improvement of body condition for several common Neotropical

migratory birds at a daily and seasonal basis demonstrate that shaded monocultures

provide quality habitat for several common wintering Neotropical-Nearctic migratory

species, as suggested elsewhere (Wunderle & Latta 1996, Greenberg et al. 1997, Petit et

al. 1999), including Cerulean Warbler. Because mixed-species flocks are affected by

habitat disturbance and fragmentation (e.g. Maldonado-Coehlo & Marini 2004, Lee et al.

2005), future work also should continue to explore the benefits of flocking for migratory

and resident birds across disturbance gradients.

131

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143

Table 4.1. First captured individuals and mean weight of 8 Neotropical migratory species

in shaded monocultures over two winter seasons in southwestern Antioquia, Colombia,

2008-2010. Values are mean ± standard deviation.

Species Trophic Guild Individuals

captured

Weight

(g)

Cerulean Warbler, Dendroica cerulea Insectivore 54 8.86 ± 0.54

Blackburnian Warbler, Dendroica fusca Insectivore 124 9.12 ± 0.57

Tennessee Warbler, Vermivora

peregrina

Nectarivore/Insectivor

e 171 9.52 ± 0.87

Canada Warbler, Wilsonia canadensis Insectivore 73 9.6 ± 0.62

Rose-breasted Grosbeak, Pheucticus

ludovicianus Omnivore 78 43.68 ± 4.95

Red-eyed Vireo, Vireo olivaceus Omnivore 28 15.63 ± 2.22

Summer Tanager, Piranga rubra Omnivore 55 30.17 ± 3.73

Empidonax flycatchers, Empidonax spp. Insectivore 41 11.85 ± 0.77

144

Table 4.2. Body condition for Neotropical-Neartic migratory birds captured in flocks and

solitary in shaded monocultures in southwestern Antioquia Department, Colombia, 2008-

2010. Values are mean ± SE. Values in parenthesis are sample sizes.

Species Flock Solitary

Cerulean Warbler -0.326 ± 0.08 (38) -0.085 ± 0.11 (16)

Blackburnian Warbler -0.035 ± 0.07 (75) 0.076 ± 0.08 (49)

Tennessee Warbler -0.004 ± 0.06 (98) -0.198 ± 0.07 (72)

Canada Warbler 0.128 ± 0.11 (29) -0.074 ± 0.09 (44)

Rose-breasted Grosbeak -0.923 ± 0.82 (42) -0.123 ± 0.67 (36)

Red-eyed Vireo 0.005 ± 0.65 (14) -0.195 ± 0.39 (14)

Summer Tanager -0.393 ± 0.91 (18) -0.611 ± 0.33 (37)

Empidonax flycatchers -0.108 ± 0.13 (10) -0.097 ± 0.09 (31)

145

Table 4.3. Result of ANOVA test for differences in body frame (PC1) between

Neotropical-Nearctic migratory birds captured in flocks and solitary in shaded

monocultures in southwestern Antioquia department, Colombia, 2008-2010. Values are

mean ± SE. Values in parenthesis are sample sizes.

Species Flock Solitary F P

Cerulean Warbler -0.078 ± 0.41 (38) -0.224 ± 0.44 (16) 0.79 0.38

Blackburnian Warbler 0.038 ± 0.24 (75) 0.057 ± 0.41 (49) 0.01 0.93

Tennessee Warbler 0.077 ± 0.22 (98) 0.001 ± 0.27 (72) 0.21 0.65

Canada Warbler -0.19 ± 0.49 (29) 0.02 ± 0.41 (44) 0.44 0.51

Rose-breasted Grosbeak 0.02 ± 0.33 (42) 0.147 ± 0.43 (36) 0.23 0.63

Red-eyed Vireo 0.306 ± 0.63 (14) -0.022 ± 0.8 (14) 0.49 0.49

Summer Tanager -0.235 ± 0.73 (18) -0.057 ± 0.38 (37) 0.24 0.63

Empidonax flycatchers 0.181 ± 0.58 (10) -0.136 ± 0.36 (31) 0.85 0.36

146

Table 4.4. Regression models to relate body condition and (1) time of day and (2) day of

season for Neotropical-Neartic migratory bird species in shaded monocultures in

southwestern Antioquia department, Colombia, 2008-2010.

Time of day Day of season

Species df F P F P

Cerulean Warbler 1, 52 5.9 0.02 0.18 0.67

Blackburnian Warbler 1, 122 11.25 0.001 2.1 0.15

Tennessee Warbler 1, 172 12.72 0.001 10.2 0.002

Canada Warbler 1, 71 26.43 0.001 1.31 0.26

Rose-breasted Grosbeak 1, 80 0.04 0.84 11.55 0.001

Red-eyed Vireo 1, 26 0.13 0.73 1.86 0.19

Summer Tanager 1, 55 0.86 0.36 9.42 0.003

Empidonax flycatchers 1, 39 1.46 0.23 0.3 0.59

147

Tabl

e 4.

5. C

oeff

icie

nts (

± SE

) of r

egre

ssio

n m

odel

s to

eval

uate

the

rela

tions

hip

betw

een

daily

cha

nges

in b

ody

cond

ition

and

floc

king

beha

vior

in N

eotro

pica

l-Nea

rtic

mig

rato

ry b

irds i

n sh

aded

mon

ocul

ture

s in

Sout

hwes

tern

Ant

ioqu

ia d

epar

tmen

t, C

olom

bia.

200

8-

2010

. Int

erac

tion

term

repr

esen

ts st

atus

x T

ime

of d

ay. P

< 0

.01*

, P <

0.0

5**,

0.0

5 <

P <

0.1*

**.

Spec

ies

N

F- fu

ll m

odel

P

Soci

al S

tatu

s Ti

me

of D

ay

Inte

ract

ion

Term

Cer

ulea

n W

arbl

er

54

3.56

0

.02

-1

.310

7 ±

0.72

31**

* 0.

0002

± 0

.000

6 0

.002

± 0

.001

*

Bla

ckbu

rnia

n W

arbl

er

124

4.61

0

.004

0.7

209

± 0.

456

0.00

16 ±

0.0

005

-0.0

01 ±

0.0

007

Tenn

esse

e W

arbl

er

176

5.98

0

.007

0.4

913

± 0.

42

0.00

17 ±

0.0

005

-0

.001

1 ±

0.00

07

Can

ada

War

bler

73

8.

89

0.0

01

0.22

36 ±

0.4

737

0.00

16 ±

0.0

005

0.00

02 ±

0.0

007

Ros

e-br

east

ed G

rosb

eak

82

0.14

0.

94

-0

.720

5 ±

2.89

18

-0

.001

6 ±

0.00

34

0.00

19 ±

0.0

048

Red

-eye

d V

ireo

28

0.9

0.45

-0

.179

± 3

.211

3 0.

0042

± 0

.003

6

-0.0

002

± 0.

0051

Sum

mer

Tan

ager

57

1.

56

0.21

4.0

283

± 3.

304

0.00

79 ±

0.0

041

-0

.007

8 ±

0.00

5

Empi

dona

x fly

catc

hers

41

0.

78

0.51

1.

1564

± 1

.730

7 0.

0029

± 0

.003

1

-0.0

023

± 0.

0032

147

148

Tabl

e 4.

6. M

ean

body

con

ditio

n fo

r eig

ht N

eotro

pica

l-Nea

rctic

mig

rato

ry b

ird sp

ecie

s in

rela

tion

to th

eir s

ocia

l sta

tus,

segr

egat

ed b

y

sex,

age

and

seas

on in

shad

ed m

onoc

ultu

res i

n so

uthw

este

rn A

ntio

quia

dep

artm

ent,

Col

ombi

a, 2

008-

2010

. Val

ues a

re m

ean

± SD

.

Sam

ple

size

in p

aren

thes

is. *

P <

0.0

5.

Spec

ies

Stat

us

Sex

Age

Se

ason

Mal

e Fe

mal

e A

dult

Juve

nile

20

08-2

009

2009

-201

0 C

erul

ean

War

bler

Fl

ock

-0.1

98 ±

0.4

82 (2

2)

-0.

511

± 0.

499

(14)

-0

.319

± 0

.488

(33)

-0

.372

± 0

.579

(5)

-0.4

96 ±

0.5

53 (1

1)

-0.2

57 ±

0.4

59 (2

7)

So

litar

y -0

.091

± 0

.46

(10)

-0

.216

± 0

.388

(5)

-0.1

04 ±

0.4

47 (1

3)

-0.0

01 ±

0.5

85 (3

) -0

.016

± 0

.393

(11)

-0

.237

± 0

.59

(5)

Bla

ckbu

rnia

n W

arbl

er

Floc

k 0

.021

± 0

.553

(33)

-

0.07

7 ±

0.61

5 (4

4)

-0.0

57 ±

0.5

64 (8

7)

-0.

073

± 0.

412

(10)

-

0.09

± 0

.543

(36)

-0

.041

± 0

.555

(61)

So

litar

y 0

.163

± 0

.515

(16)

0.0

33 ±

0.5

86 (3

4)

0.0

52 ±

0.5

47 (5

4)

0.1

79 ±

0.3

21 (7

) 0

.044

± 0

.509

(24)

0.

081

± 0.

54 (3

7)

Tenn

esse

e W

arbl

er

Floc

k 0

.067

± 0

.739

(52)

-

0.21

5 ±

0.66

7 (3

6)

-0.0

15 ±

0.7

33 (1

02)

- 0

.164

± 0

.827

(41)

-0

.134

± 0

.643

(61)

So

litar

y 0

.048

± 0

.858

(38)

-

0.26

5 ±

0.84

9 (2

6)

-0.0

01 ±

0.9

16 (7

5)

-0.3

95 ±

0.7

3 (3

) -0

.051

± 0

.78

(32)

0

.006

± 0

.992

(46)

Can

ada

War

bler

Fl

ock

0.0

14 ±

0.7

23 (1

3)

0.

168

± 0.

547

(13)

0

.113

± 0

.609

(31)

0.

525

(1)

0.22

4 ±

0.59

3 (1

1)

0.0

91 ±

0.6

17 (2

1)

So

litar

y 0

.042

± 0

.683

(18)

-0

.187

± 0

.56

(21)

-0

.064

± 0

.614

(41)

-

0.14

3 ±

0.15

3 (2

) 0.

014

± 0.

598

(20)

-0

.147

± 0

.593

(24)

Ros

e-br

east

ed G

rosb

eak

Floc

k -0

.151

± 5

.773

(29)

-

2.19

6 ±

4.96

9 (1

7)

-0.8

94 ±

5.5

77 (4

5)

-2.2

26 (1

) -1

.237

± 2

.835

(16)

-0.7

5 ±

6.59

1 (3

0)

So

litar

y -0

.012

± 4

.587

(22)

-

0.28

5 ±

3.30

1 (1

6)

-0.1

23 ±

4.0

66 (3

8)

- -0

.031

± 5

.095

(18)

-0

.201

± 3

.073

(20)

Red

-eye

d V

ireo

Floc

k -

- -0

.937

± 2

.585

(7)

0.9

47 ±

1.9

78 (8

) 0

.46

± 2.

382

(4)

-0.1

77 ±

2.5

34 (1

1)

So

litar

y -

- -0

.331

± 1

.559

(10)

0

.146

± 1

.356

(4)

-0.4

84 ±

2.5

76 (4

) -0

.079

± 0

.923

(10)

Sum

mer

Tan

ager

Fl

ock

1.8

77 ±

4.1

11 (1

4)

-2.

385

± 2.

066

(6)*

0.

598

± 4.

087

(20)

-

0.9

62 ±

4.0

84 (1

2)

0.05

3 ±

4.30

8 (8

)

So

litar

y -0

.523

± 2

.104

(23)

-0

.533

± 2

.08

(10)

-0

.579

± 2

.061

(36)

-1

.739

(1)

-0.3

14 ±

2.3

59 (2

1)

-

1.0

± 1.

512

(16)

Empi

dona

x fly

catc

hers

Fl

ock

- -

-0.1

08 ±

0.4

18 (1

2)

- -0

.294

± 0

.618

(5)

-0.0

28 ±

0.3

31 (7

)

So

litar

y -

- -

0.07

6 ±

0.51

(27)

-0

.203

± 0

.472

(5)

-0.0

57 ±

0.4

56 (2

4)

-0.2

32 ±

0.6

47 (8

)

148

149

Tabl

e 4.

7. C

oeff

icie

nts (

± SE

) of r

egre

ssio

n m

odel

s to

eval

uate

the

rela

tions

hip

betw

een

seas

onal

cha

nges

in b

ody

cond

ition

and

flock

ing

beha

vior

in N

eotro

pica

l-Nea

rtic

mig

rato

ry b

irds i

n sh

aded

mon

ocul

ture

s in

Sout

hwes

tern

Ant

ioqu

ia d

epar

tmen

t, C

olom

bia.

Inte

ract

ion

term

repr

esen

ts st

atus

x D

ay o

f sea

son.

P <

0.0

1*, P

< 0

.05*

*, 0

.05

< P

< 0.

1***

. ***

. Em

pido

nax

Flyc

atch

ers w

ere

excl

uded

from

this

ana

lysi

s for

lack

of i

ndiv

idua

ls c

augh

t in

flock

s lat

er in

the

seas

on.

Spec

ies

N

F- fu

ll m

odel

P

Soci

al S

tatu

s D

ay o

f Sea

son

Inte

ract

ion

Term

Cer

ulea

n W

arbl

er

54

0.98

0.

41

0.18

42 ±

0.4

161

0.00

05 ±

0.0

019

0.00

05 ±

0.0

032

Bla

ckbu

rnia

n W

arbl

er

124

3.44

0.

02

0.5

76 ±

0.3

072*

**

-0.0

006

± 0.

0013

0.

005

± 0.

002*

*

Tenn

esse

e W

arbl

er

176

4.66

0.

004

-

0.47

61 ±

0.5

335

0.00

44 ±

0.0

02

0.00

18 ±

0.0

031

Can

ada

War

bler

73

1.

19

0.32

-0.3

9 ±

0.33

54

-0.0

024

± 0.

002

0.00

17 ±

0.0

026

Ros

e-br

east

ed G

rosb

eak

82

4.56

0.

006

1.68

66 ±

2.1

066

0.02

81 ±

0.0

084

-0.0

132

± 0.

0131

Red

-eye

d V

ireo

28

1.81

0.

17

-

2.01

52 ±

2.0

481

-0.0

187

± 0.

0085

0.

0126

9 ±

0.01

219

Sum

mer

Tan

ager

57

3.

48

0.02

1.

9203

± 2

.415

2 0.

0302

± 0

.012

5 -0

.014

8 ±

0.01

5

149

150

Tabl

e 4.

8. F

-test

for c

ompa

rison

of s

tand

ard

devi

atio

ns o

f bod

y co

nditi

on b

etw

een

flock

and

solit

ary

indi

vidu

als f

or N

eotro

pica

l-

Nea

rctic

mig

rato

ry b

irds i

n sh

aded

mon

ocul

ture

s in

Sout

hwes

tern

Ant

ioqu

ia d

epar

tmen

t, C

olom

bia.

Spec

ies

Floc

k So

litar

y F

df

P

Cer

ulea

n W

arbl

er

0.49

3 0.

455

1.17

37

, 15

0.77

Bla

ckbu

rnia

n W

arbl

er

0.58

7 0.

562

1.09

74

, 48

0.75

Tenn

esse

e W

arbl

er

0.69

6 0.

661

1.11

98

, 71

0.65

Can

ada

War

bler

0.

603

0.59

4 1.

03

28, 4

3 0.

91

Ros

e-br

east

ed G

rosb

eak

3.22

1 3.

172

1.03

42

, 36

0.93

Red

-eye

d V

ireo

2.41

8 1.

469

2.71

13

, 13

0.08

Sum

mer

Tan

ager

2.

871

2.04

1 1.

98

17, 3

6 0.

08

Empi

dona

x fly

catc

hers

0.

4179

0.

499

0.7

9, 3

0 0.

6

150

151

Figu

re 4

.1.B

andi

ng st

atio

ns in

Sou

thw

este

rn A

ntio

quia

dep

artm

ent,

Col

ombi

a. 1

. Gua

land

ay fa

rm, F

redo

nia

Mun

icip

ality

, 2.

Cul

tivar

es fa

rm, J

eric

o M

unic

ipal

ity a

nd 3

. La

Cum

bre

farm

, Tam

esis

Mun

icip

ality

. Sou

rce:

msn

Enc

arta

.

151

152

Figu

re 4

.2.R

elat

ions

hip

betw

een

daily

bod

y co

nditi

on a

nd so

cial

stat

us in

Neo

tropi

cal m

igra

tory

bird

spec

ies i

n sh

aded

mon

ocul

ture

s

in A

ntio

quia

dep

artm

ent,

Col

ombi

a. O

pen

circ

le w

ith so

lid li

ne: b

irds i

n flo

cks.

Clo

sed

circ

le w

ith d

otte

d lin

e: so

litar

y bi

rds.

6:00

8:00

10:0

012

:00

14:0

016

:00

18:0

0-1

.4-1

-0.6

-0.20.2

0.61

BCI CERW

Floc

kSo

litary

6:00

8:00

10:0

012

:00

14:0

016

:00

18:0

0-1

-0.50

0.51

1.52

BCI BLWA

BCI TEWA

Hour

6:00

8:00

10:0

012

:00

14:0

016

:00

18:0

0-1

.8

-0.80.2

1.2

2.2

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APPENDICES

Appendix A. Field design for Neotropical-Nearctic migratory birds and mixed-species

flocks surveys in the Northern and Central Andes.

A predictive map to elucidate occurrence of Cerulean Warbler in the Andes was created

by members of El Grupo Ceruleo, a subcommittee of the Cerulean Warbler technical

group. This map was developed by the combination of five GIS hypothetical models of

potential distribution of the bird in the Northern and Central Andes (Barker et al. 20061).

This map then represents the locations with the highest probability of occurrence of the

species. We used a stratified-random design to select 20 locations (hereafter called

random points) to verify the occurrence of the species (Colorado et al. 20082), and I

applied this design to accomplish the aims of chapter 2 and chapter 3 of my dissertation.

Each of these random points, represented by a 1-km2 area (or pixel) in the GIS map, was

predicted as potential habitat by all five hypothetical models. Each of these 20 random

points was paired with a randomly selected point (paired point) defined to have been

selected by three or fewer of the five models as potential habitat within a 5-km circus

radius of the random point. Finally, around each of the random and paired points a

systematically arrayed grid of four additional 1-km2 survey sites oriented in the cardinal

directions and located 1 km from the central random or paired point was selected. The

resulting total was ten 1-km2 pixels (i.e. one random point and four cardinal random

points, plus one paired point and four cardinal paired points) at each one of the 20

190

locations. The final sample consisted of two hundred 1-km2 pixels in the Northern and

Central Andes.

1 Barker, S., S. Benítez, J. Baldy, D. Cisneros H., G. Colorado, F. Cuesta, I. Davidson, D.

Díaz, A. Ganzenmueller, S. García, M. K. Girvan, E. Guevara, P. Hamel, A. B.

Hennessey, O. L. Hernández, S. Herzog, D. Mehlman, M. I. Moreno, E.

Ozdenerol, P. Ramoni-Perazzi, M. Romero, D. Romo, P. Salaman, T. Santander,

C. Tovar, M. Welton, T. Will, C. Pedraza, & G. Galindo. 2006. Modeling the

South American Range of the Cerulean Warbler. Proceedings of the 26th ESRI

International User Conference.

2 Colorado G., Hamel P., Rodewald A. and W. Thogmartin. 2008. El grupo cerúleo:

collaboration to assess nonbreeding range of cerulean warbler in south America.

Ornitologia Neotropical (suppl.) 19: 521-529.

191

Appendix B. Presence-absence matrix built from the species pool of flocking species in

the locality of Aguachica, Eastern Andes, Colombia.

Species

Floc

k 1

Floc

k 2

Floc

k 3

Floc

k 4

Floc

k 5

Floc

k 6

Floc

k 7

Floc

k 8

Floc

k 9

Floc

k 10

Floc

k 11

Floc

k 12

Xenops minutes 0 0 0 0 0 0 0 0 1 0 0 0

Xiphorhynchus triangularis 0 0 0 0 0 0 0 0 1 0 0 0

Dysithamnus mentalis 0 0 1 0 0 0 0 0 0 0 0 0

Cymbilaimus lineatus 0 0 0 0 1 0 0 0 0 0 0 0

Todirostrum cinereum 0 0 0 0 0 0 1 0 0 1 0 0

Leptopogon amaurocephalus 0 0 0 0 0 0 0 0 0 1 0 0

Phylloscartes ophtalmicus 0 0 0 0 0 0 0 0 0 1 0 1

Myiodynastes maculatus 1 0 0 0 0 0 0 0 0 0 0 0

Empidonax spp. 0 0 0 0 0 0 1 1 0 0 0 0

Phyllomyias nigrocapillus 0 0 1 0 0 0 0 0 0 0 0 0

Myiarchus cephalotes 0 0 0 1 1 0 0 0 0 0 0 0

Mionectes oleagineus 0 0 0 0 1 0 0 0 0 0 0 0

Elaenia flavogaster 0 0 0 0 0 0 1 0 0 0 0 0

Chiroxiphia lanceolata 0 0 0 0 0 0 0 1 0 1 0 0

Corapipo leucorrhoa 0 0 0 0 0 0 0 0 0 0 0 1

Thryothorus rufalbus 0 0 0 0 0 0 0 0 0 0 0 1

Catharus aurantiirostris 0 0 0 0 0 0 0 0 0 0 0 1

continued

192

Appendix B. (continued)

Turdus leucomelas 0 0 1 0 0 0 0 0 0 0 0 0

Hylophilus flavipes 0 0 0 1 1 0 0 0 0 0 0 0

Mniotilta varia 1 0 1 1 1 0 0 0 0 0 0 0

Dendroica fusca 1 0 0 1 0 0 0 0 0 0 0 0

Vermivora peregrina 1 0 0 1 1 1 0 1 1 0 1 0

Parula pitiayumi 0 0 0 0 0 0 0 0 0 1 0 0

Basileuterus culicivorus 1 1 1 1 0 0 0 1 1 0 0 1

Basileuterus rufifrons 0 1 0 0 0 0 1 0 1 1 0 1

Basileuterus cinereicollis 0 0 1 1 0 0 0 0 0 0 0 0

Euphonia laniirostris 0 0 0 0 1 0 0 0 0 0 1 0

Thraupis episcopus 0 0 0 0 0 1 1 0 0 0 0 0

Thraupis palmarum 0 0 0 0 1 0 0 0 0 0 0 0

Ramphocelus carbo 0 0 0 0 0 0 0 1 0 1 1 0

Tangara gyrola 0 0 0 1 1 0 0 0 0 0 0 0

Tangara guttata 0 0 1 1 1 0 1 0 0 0 0 0

Tangara cyanoptera 0 0 0 0 0 0 1 0 1 0 0 0

Piranga rubra 0 0 0 0 0 0 0 0 1 1 0 0

Chlorospingus canigularis 0 0 0 0 0 0 0 0 0 0 0 1

Rhodinocichla rosea 0 1 0 0 0 0 0 0 0 0 0 0

Pheucticus ludovicianus 1 0 0 0 1 0 0 0 0 0 0 0

Arremon schlegeli 0 1 0 0 0 0 0 0 1 1 0 0

Atlapetes rufinuchus 0 0 0 0 0 0 0 0 0 0 0 1

Arremon torquatus 0 0 0 0 0 0 0 0 0 0 0 1

Continued

193

Appendix B. (continued)

Saltator striatipectus 0 0 0 0 0 1 0 1 0 1 0 0

Saltator maximus 0 0 0 0 0 0 0 0 0 1 0 0

Tiaris fuliginosus 0 0 0 0 0 0 0 1 0 0 0 0

Volatinia jacarina 0 0 0 0 0 0 0 0 0 1 0 0

194

Appendix C. Percentage of species per guild in 311 mixed-species bird flocks recorded

in 13 regions in the Andes. 2007-2010.

Region Flock No. Frugivore Omnivore Insectivore Nectarivore No. species

No. % No. % No. % No. %

Carache Flock 1 7 46.7 0 0.0 8 53.3 0 0.0 15

Carache Flock 2 9 64.3 0 0.0 5 35.7 0 0.0 14

Carache Flock 3 6 46.2 0 0.0 7 53.8 0 0.0 13

Carache Flock 4 5 62.5 0 0.0 3 37.5 0 0.0 8

Carache Flock 5 8 61.5 0 0.0 5 38.5 0 0.0 13

Carache Flock 6 7 53.8 0 0.0 6 46.2 0 0.0 13

Carache Flock 7 2 25.0 0 0.0 6 75.0 0 0.0 8

Carache Flock 8 1 16.7 0 0.0 5 83.3 0 0.0 6

Carache Flock 9 6 60.0 0 0.0 4 40.0 0 0.0 10

Carache Flock 10 4 66.7 0 0.0 2 33.3 0 0.0 6

Carache Flock 11 5 62.5 1 12.5 2 25.0 0 0.0 8

Carache Flock 12 7 70.0 0 0.0 2 20.0 1 10.0 10

Carache Flock 13 3 75.0 0 0.0 1 25.0 0 0.0 4

Carache Flock 14 1 25.0 0 0.0 3 75.0 0 0.0 4

Carache Flock 15 3 60.0 0 0.0 2 40.0 0 0.0 5

Carache Flock 16 4 66.7 0 0.0 2 33.3 0 0.0 6

Carache Flock 17 1 33.3 0 0.0 2 66.7 0 0.0 3

Carache Flock 18 2 100.0 0 0.0 0 0.0 0 0.0 2

Carache Flock 19 4 100.0 0 0.0 0 0.0 0 0.0 4

continued

195

Appendix C. (continued)

Carache Flock 20 5 71.4 0 0.0 2 28.6 0 0.0 7

Carache Flock 21 4 80.0 0 0.0 1 20.0 0 0.0 5

Carache Flock 22 2 66.7 0 0.0 1 33.3 0 0.0 3

Carache Flock 23 3 100.0 0 0.0 0 0.0 0 0.0 3

Carache Flock 24 2 40.0 2 40.0 1 20.0 0 0.0 5

Carache Flock 25 8 61.5 0 0.0 5 38.5 0 0.0 13

Carache Flock 26 3 50.0 0 0.0 3 50.0 0 0.0 6

Carache Flock 27 1 25.0 0 0.0 3 75.0 0 0.0 4

Carache Flock 28 3 100.0 0 0.0 0 0.0 0 0.0 3

Carache Flock 29 2 66.7 0 0.0 1 33.3 0 0.0 3

Carache Flock 30 2 66.7 0 0.0 1 33.3 0 0.0 3

Carache Flock 31 0 0.0 0 0.0 2 66.7 1 33.3 3

Carache Flock 32 1 50.0 0 0.0 1 50.0 0 0.0 2

Carache Flock 33 4 50.0 0 0.0 4 50.0 0 0.0 8

Carache Flock 34 3 50.0 1 16.7 2 33.3 0 0.0 6

Aguachica Flock 35 1 16.7 0 0.0 5 83.3 0 0.0 6

Aguachica Flock 36 0 0.0 2 50.0 2 50.0 0 0.0 4

Aguachica Flock 37 3 37.5 0 0.0 5 62.5 0 0.0 8

Aguachica Flock 38 2 22.2 0 0.0 7 77.8 0 0.0 9

Aguachica Flock 39 6 54.5 0 0.0 5 45.5 0 0.0 11

Aguachica Flock 40 2 66.7 0 0.0 1 33.3 0 0.0 3

Aguachica Flock 41 4 57.1 0 0.0 3 42.9 0 0.0 7

Aguachica Flock 42 3 42.9 1 14.3 3 42.9 0 0.0 7

Aguachica Flock 43 2 25.0 1 12.5 5 62.5 0 0.0 8

Aguachica Flock 44 5 41.7 2 16.7 5 41.7 0 0.0 12

Aguachica Flock 45 2 66.7 0 0.0 1 33.3 0 0.0 3

continued

196


Aguachica Flock 46 4 44.4 1 11.1 4 44.4 0 0.0 9

San Jose de la Montana Flock 47 3 37.5 0 0.0 5 62.5 0 0.0 8

























continued

197



Yariguies Flock 73 9 69.2 0 0.0 4 30.8 0 0.0 13

Yariguies Flock 74 7 50.0 0 0.0 7 50.0 0 0.0 14

Yariguies Flock 75 4 30.8 0 0.0 9 69.2 0 0.0 13

Yariguies Flock 76 9 47.4 0 0.0 10 52.6 0 0.0 19

Yariguies Flock 77 3 25.0 0 0.0 8 66.7 1 8.3 12

Yariguies Flock 78 1 12.5 0 0.0 7 87.5 0 0.0 8

Yariguies Flock 79 3 42.9 0 0.0 4 57.1 0 0.0 7

Chicamocha Flock 80 6 85.7 0 0.0 1 14.3 0 0.0 7



Abejorral Flock 83 1 16.7 0 0.0 5 83.3 0 0.0 6

Abejorral Flock 84 6 50.0 0 0.0 5 41.7 1 8.3 12

Abejorral Flock 85 4 80.0 0 0.0 1 20.0 0 0.0 5

Abejorral Flock 86 4 66.7 0 0.0 2 33.3 0 0.0 6

Abejorral Flock 87 4 40.0 1 10.0 4 40.0 1 10.0 10

Abejorral Flock 88 10 47.6 1 4.8 10 47.6 0 0.0 21

Abejorral Flock 89 2 25.0 0 0.0 6 75.0 0 0.0 8

Abejorral Flock 90 9 50.0 1 5.6 8 44.4 0 0.0 18

Abejorral Flock 91 3 33.3 0 0.0 5 55.6 1 11.1 9

Abejorral Flock 92 3 60.0 0 0.0 1 20.0 1 20.0 5

Abejorral Flock 93 11 61.1 1 5.6 5 27.8 1 5.6 18

Abejorral Flock 94 5 50.0 0 0.0 4 40.0 1 10.0 10

Abejorral Flock 95 2 50.0 0 0.0 2 50.0 0 0.0 4

Abejorral Flock 96 3 60.0 0 0.0 1 20.0 1 20.0 5

Abejorral Flock 97 2 20.0 1 10.0 6 60.0 1 10.0 10

continued

198


Abejorral Flock 98 8 44.4 1 5.6 8 44.4 1 5.6 18

Abejorral Flock 99 3 37.5 1 12.5 4 50.0 0 0.0 8

Abejorral Flock 100 4 80.0 0 0.0 1 20.0 0 0.0 5

Abejorral Flock 101 5 62.5 0 0.0 3 37.5 0 0.0 8

Abejorral Flock 102 5 62.5 0 0.0 3 37.5 0 0.0 8

Abejorral Flock 103 5 83.3 0 0.0 1 16.7 0 0.0 6

Abejorral Flock 104 2 66.7 0 0.0 0 0.0 1 33.3 3

Abejorral Flock 105 3 75.0 0 0.0 1 25.0 0 0.0 4

Abejorral Flock 106 3 42.9 0 0.0 4 57.1 0 0.0 7

Abejorral Flock 107 6 85.7 0 0.0 1 14.3 0 0.0 7

Abejorral Flock 108 1 16.7 0 0.0 4 66.7 1 16.7 6

Abejorral Flock 109 3 60.0 0 0.0 2 40.0 0 0.0 5

Abejorral Flock 110 5 71.4 0 0.0 2 28.6 0 0.0 7

Abejorral Flock 111 9 52.9 1 5.9 6 35.3 1 5.9 17

Abejorral Flock 112 1 33.3 0 0.0 2 66.7 0 0.0 3

Abejorral Flock 113 11 57.9 0 0.0 7 36.8 1 5.3 19

Abejorral Flock 114 9 56.3 1 6.3 5 31.3 1 6.3 16

Abejorral Flock 115 6 28.6 1 4.8 13 61.9 1 4.8 21

Abejorral Flock 116 4 100.0 0 0.0 0 0.0 0 0.0 4

Abejorral Flock 117 1 50.0 0 0.0 0 0.0 1 50.0 2

Abejorral Flock 118 3 100.0 0 0.0 0 0.0 0 0.0 3

Paya Flock 119 5 83.3 0 0.0 1 16.7 0 0.0 6

Paya Flock 120 2 33.3 0 0.0 3 50.0 1 16.7 6

Paya Flock 121 2 40.0 0 0.0 3 60.0 0 0.0 5

Paya Flock 122 4 50.0 0 0.0 4 50.0 0 0.0 8

Paya Flock 123 4 50.0 0 0.0 4 50.0 0 0.0 8

continued

199


Paya Flock 124 5 50.0 0 0.0 5 50.0 0 0.0 10

Paya Flock 125 3 50.0 0 0.0 3 50.0 0 0.0 6

Paya Flock 126 3 42.9 0 0.0 4 57.1 0 0.0 7

Paya Flock 127 3 33.3 0 0.0 5 55.6 1 11.1 9

Paya Flock 128 4 66.7 0 0.0 2 33.3 0 0.0 6

Paya Flock 129 1 25.0 0 0.0 3 75.0 0 0.0 4

Paya Flock 130 3 50.0 0 0.0 2 33.3 1 16.7 6

Paya Flock 131 4 66.7 0 0.0 1 16.7 1 16.7 6

Paya Flock 132 3 42.9 0 0.0 4 57.1 0 0.0 7

Paya Flock 133 3 75.0 0 0.0 1 25.0 0 0.0 4

Tolima Flock 134 5 50.0 0 0.0 5 50.0 0 0.0 10

Tolima Flock 135 1 33.3 0 0.0 2 66.7 0 0.0 3

Cauca Flock 136 6 42.9 0 0.0 8 57.1 0 0.0 14

Cauca Flock 137 3 50.0 2 33.3 1 16.7 0 0.0 6

Cauca Flock 138 2 28.6 0 0.0 4 57.1 1 14.3 7

Cauca Flock 139 8 80.0 0 0.0 2 20.0 0 0.0 10

Cauca Flock 140 6 60.0 0 0.0 4 40.0 0 0.0 10

Cauca Flock 141 8 61.5 0 0.0 5 38.5 0 0.0 13

Cauca Flock 142 6 60.0 1 10.0 3 30.0 0 0.0 10

Cauca Flock 143 2 25.0 1 12.5 5 62.5 0 0.0 8

Cauca Flock 144 7 58.3 1 8.3 4 33.3 0 0.0 12

Cauca Flock 145 8 72.7 1 9.1 2 18.2 0 0.0 11

Cauca Flock 146 5 45.5 1 9.1 5 45.5 0 0.0 11

Cauca Flock 147 6 75.0 0 0.0 2 25.0 0 0.0 8

Cauca Flock 148 2 40.0 1 20.0 1 20.0 1 20.0 5

Cauca Flock 149 1 25.0 0 0.0 3 75.0 0 0.0 4

continued

200


Cauca Flock 150 1 33.3 0 0.0 2 66.7 0 0.0 3

Cauca Flock 151 3 60.0 0 0.0 2 40.0 0 0.0 5

Cauca Flock 152 3 50.0 0 0.0 2 33.3 1 16.7 6

Cauca Flock 153 11 57.9 0 0.0 7 36.8 1 5.3 19

Cauca Flock 154 1 20.0 0 0.0 3 60.0 1 20.0 5

Cauca Flock 155 9 64.3 0 0.0 5 35.7 0 0.0 14

Cauca Flock 156 4 57.1 0 0.0 3 42.9 0 0.0 7

Cauca Flock 157 5 55.6 0 0.0 3 33.3 1 11.1 9

Cauca Flock 158 7 63.6 0 0.0 3 27.3 1 9.1 11

Cauca Flock 159 0 0.0 2 28.6 4 57.1 1 14.3 7

Cauca Flock 160 9 50.0 0 0.0 8 44.4 1 5.6 18

Cauca Flock 161 6 54.5 0 0.0 5 45.5 0 0.0 11

Cauca Flock 162 7 70.0 0 0.0 3 30.0 0 0.0 10

Cauca Flock 163 3 42.9 0 0.0 4 57.1 0 0.0 7

Cauca Flock 164 4 80.0 0 0.0 1 20.0 0 0.0 5

Sangay National Park Flock 165 4 44.4 1 11.1 4 44.4 0 0.0 9








Cajamarca Flock 173 3 75.0 0 0.0 1 25.0 0 0.0 4

Cajamarca Flock 174 5 62.5 0 0.0 3 37.5 0 0.0 8

Cajamarca Flock 175 5 83.3 0 0.0 1 16.7 0 0.0 6

continued

201


Cajamarca Flock 176 2 66.7 0 0.0 0 0.0 1 33.3 3

Cajamarca Flock 177 3 75.0 0 0.0 1 25.0 0 0.0 4

Cajamarca Flock 178 2 20.0 0 0.0 7 70.0 1 10.0 10

Cajamarca Flock 179 3 33.3 0 0.0 6 66.7 0 0.0 9

Cajamarca Flock 180 6 66.7 0 0.0 3 33.3 0 0.0 9

Cajamarca Flock 181 5 38.5 0 0.0 8 61.5 0 0.0 13

Cajamarca Flock 182 2 25.0 0 0.0 6 75.0 0 0.0 8

Cajamarca Flock 183 1 25.0 0 0.0 3 75.0 0 0.0 4

Cajamarca Flock 184 2 50.0 0 0.0 2 50.0 0 0.0 4

Cajamarca Flock 185 2 50.0 0 0.0 2 50.0 0 0.0 4

Cajamarca Flock 186 0 0.0 2 50.0 2 50.0 0 0.0 4

Cajamarca Flock 187 3 37.5 0 0.0 5 62.5 0 0.0 8

Cajamarca Flock 188 2 22.2 0 0.0 7 77.8 0 0.0 9

Cajamarca Flock 189 6 54.5 0 0.0 5 45.5 0 0.0 11

Pacora Flock 190 4 50.0 0 0.0 4 50.0 0 0.0 8

Pacora Flock 191 2 40.0 0 0.0 3 60.0 0 0.0 5

Pacora Flock 192 3 75.0 0 0.0 1 25.0 0 0.0 4

Pacora Flock 193 6 66.7 0 0.0 3 33.3 0 0.0 9

Pacora Flock 194 6 50.0 0 0.0 6 50.0 0 0.0 12

Pacora Flock 195 3 27.3 0 0.0 7 63.6 1 9.1 11

Pacora Flock 196 4 57.1 0 0.0 3 42.9 0 0.0 7

Pacora Flock 197 5 55.6 0 0.0 4 44.4 0 0.0 9

Pacora Flock 198 3 33.3 0 0.0 6 66.7 0 0.0 9

Pacora Flock 199 1 33.3 0 0.0 2 66.7 0 0.0 3

Pacora Flock 200 4 57.1 0 0.0 3 42.9 0 0.0 7

Pacora Flock 201 4 66.7 0 0.0 2 33.3 0 0.0 6

continued

202


Pacora Flock 202 3 60.0 0 0.0 2 40.0 0 0.0 5

Pacora Flock 203 1 25.0 0 0.0 3 75.0 0 0.0 4

Pacora Flock 204 2 50.0 0 0.0 2 50.0 0 0.0 4

Pacora Flock 205 2 50.0 0 0.0 2 50.0 0 0.0 4

Pacora Flock 206 3 60.0 0 0.0 2 40.0 0 0.0 5

Pacora Flock 207 3 42.9 0 0.0 4 57.1 0 0.0 7

Pacora Flock 208 4 57.1 0 0.0 2 28.6 1 14.3 7

Pacora Flock 209 3 60.0 0 0.0 1 20.0 1 20.0 5

Pacora Flock 210 4 50.0 0 0.0 4 50.0 0 0.0 8

Pacora Flock 211 4 66.7 0 0.0 2 33.3 0 0.0 6

SW Antioquia Flock 212 2 20.0 0 0.0 7 70.0 1 10.0 10
















continued

203




























continued

204




























continued

205




























continued

206








207

Appendix D. Bird species and families recorded in 311 mixed-species flocks in the

Andes, 2007-2010.

Species Family Guilds

Piaya cayana Cuculidae Insectivore-frugivore

Eubucco bourcierii Capitonidae Frugivore-insectivore

Veniliornis kirkii Picidae Insectivore

Picoides fumigatus Picidae Insectivore

Melanerpes rubricapillus Picidae Insectivore

Melanerpes formicivorus Picidae Insectivore

Picumnus granadensis Picidae Insectivore

Picumnus squamulatus Picidae Insectivore

Picumnus olivaceus Picidae Insectivore

Colaptes rubiginosus Picidae Insectivore

Colaptes punctigula Picidae Insectivore

Dryocopus lineatus Picidae Insectivore

Piculus rivolii Picidae Insectivore

Trogon personatus Trogonidae Frugivore-insectivore

Furnariidae Furnariidae Insectivore

Lepidocolaptes souleyetii Furnariidae Insectivore

Continued

208

Appendix D. (continued)

Lepidocolaptes affinis Furnariidae Insectivore

Lepidocolaptes lacrymiger Furnariidae Insectivore

Dendrocincla fuliginosa Furnariidae Insectivore

Anabacerthia striaticollis Furnariidae Insectivore

Automolus ochrolaemus Furnariidae Insectivore

Xenops rutilans Furnariidae Insectivore

Xenops minutus Furnariidae Insectivore

Dendrocincla homochroa Furnariidae Insectivore

Sittasomus griseicapillus Furnariidae Insectivore

Xiphorhynchus flavigaster Furnariidae Insectivore

Xiphorhynchus susurrans Furnariidae Insectivore

Xiphorhynchus triangularis Furnariidae Insectivore

Cranioleuca erythrops Furnariidae Insectivore

Synallaxis azarae Furnariidae Insectivore

Synallaxis subpudica Furnariidae Insectivore

Synallaxis brachyura Furnariidae Insectivore

Synallaxis albescens Furnariidae Insectivore

Glyphorhynchus spirurus Furnariidae Insectivore

Xyphorhynchus picus Furnariidae Insectivore

Myiarchus cephalotes Tyrannidae Insectivore-frugivore

Myiotriccus ornatus Tyrannidae Insectivore-frugivore

Continued

209


Mionectes striaticollis Tyrannidae Frugivore-insectivore

Mionectes oleagineus Tyrannidae Frugivore-insectivore

Poecilotricus ruficeps Tyrannidae Insectivore

Elaenia frantzii Tyrannidae Frugivore-insectivore

Elaenia flavogaster Tyrannidae Frugivore-insectivore

Phyrromyias cinnamomeus Tyrannidae Insectivore

Tyrannus melancholicus Tyrannidae Insectivore-frugivore

Mecocerculus leucophrys Tyrannidae Insectivore-frugivore

Myiophobus flavicans Tyrannidae Insectivore-frugivore

Ochthoeca fumicolor Tyrannidae Insectivore

Ochthoeca rufipectoralis Tyrannidae Insectivore

Cyanocorax yncas Corvidae Omnivore

Chiroxiphia lanceolata Pipridae Frugivore

Corapipo leucorrhoa Pipridae Frugivore

Manacus manacus Pipridae Frugivore

Henicorhina leucosticta Troglodytidae Insectivore

Henicorhina leucophrys Troglodytidae Insectivore

Thryothorus mystacalis Troglodytidae Insectivore

Thryothorus maculipectus Troglodytidae Insectivore

Thryothorys genibarbis Troglodytidae Insectivore

Thryothorus leucotis Troglodytidae Insectivore

Continued

210


Thryothorus rufalbus Troglodytidae Insectivore

Catharus aurantiirostris Turdidae Frugivore-insectivore

Catharus ustulatus Turdidae Frugivore-insectivore

Turdus ignobilis Turdidae Frugivore-insectivore

Turdus serranus Turdidae Frugivore-insectivore

Turdus flavipes Turdidae Frugivore-insectivore

Myadestes ralloides Turdidae Frugivore-insectivore

Turdus grayi Turdidae Frugivore-insectivore

Turdus olivater Turdidae Frugivore-insectivore

Turdus obsoletus Turdidae Frugivore-insectivore

Turdus fuscater Turdidae Frugivore-insectivore

Turdus leucomelas Turdidae Frugivore-insectivore

Diglossa cyanea Thraupidae Nectarivore-Insectivore

Diglossa albilatera Thraupidae Nectarivore-Insectivore

Diglossa caerulescens Thraupidae Nectarivore-Insectivore

Mimus gilvus Mimidae Insectivore-frugivore

Euphonia cyanocephala Fringillidae Frugivore

Euphonia xanthogaster Fringillidae Frugivore

Euphonia laniirostris Fringillidae Frugivore

Euphonia mesochrysa Fringillidae Frugivore

Euphonia_trinitatis Fringillidae Frugivore

Continued

211


Euphonia_saturata Thraupidae Frugivore

Hemithraupis guira Thraupidae Frugivore-insectivore

Hemithraupis flavirostris Thraupidae Frugivore-insectivore

Thraupis episcopus Thraupidae Frugivore

Thraupis palmarum Thraupidae Frugivore

Thraupis cyanocephala Thraupidae Frugivore

Ramphocelus dimidiatus Thraupidae Frugivore

Ramphocelus flammigerus Thraupidae Frugivore

Ramphocelus carbo Thraupidae Frugivore

Tangara vitriolina Thraupidae Frugivore

Tangara gyrola Thraupidae Frugivore

Tangara cyanicollis Thraupidae Frugivore

Tangara heinei Thraupidae Frugivore

Tangara nigroviridis Thraupidae Frugivore

Tangara xanthocephala Thraupidae Frugivore

Tangara arthus Thraupidae Frugivore

Tangara vassorii Thraupidae Frugivore

Tangara parzudakii Thraupidae Frugivore

Tangara guttata Thraupidae Frugivore

Tangara schrankii Thraupidae Frugivore

Tangara chilensis Thraupidae Frugivore

Continued

212


Tangara cyanoptera Thraupidae Frugivore

Tangara labradorides Thraupidae Frugivore

Tangara ruficervix Thraupidae Frugivore

Tangara cayana Thraupidae Frugivore

Piranga flava Cardinalidae Frugivore-insectivore

Zonotrichia capensis Emberizidae Granivore

Saltator striatipectus Incertae sedis Frugivore-granivore

Saltator atripennis Incertae sedis Frugivore-granivore

Saltator coerulescens Incertae sedis Frugivore-granivore

Saltator maximus Incertae sedis Frugivore-granivore

Fringillidae Fringillidae Frugivore

Syndactyla subalaris Furnariidae Insectivore

Pseudocolaptes boissonneautii Furnariidae Insectivore

Margarornis squamiger Furnariidae Insectivore

Thamnophilus multistriatus Thamnophilidae Insectivore

Thamnophilus doliatus Thamnophilidae Insectivore

Dysithamnus mentalis Thamnophilidae Insectivore

Cymbilaimus lineatus Thamnophilidae Insectivore

Scytalopus sp. Rhinocryptidae Insectivore

Pachyramphus polychopterus Tityridae Frugivore-insectivore

Pachyramphus rufus Tityridae Frugivore-insectivore

Continued

213


Pachyramphus versicolor Tityridae Frugivore-insectivore

Pipreola riefferii Cotingidae Frugivore

Myiarchus tuberculifer Tyrannidae Insectivore

Zymmerius chrysops Tyrannidae Insectivore

Zymmerius villissimus Tyrannidae Insectivore

Camptostoma obsoletum Tyrannidae Insectivore

Todirostrum cinereum Tyrannidae Insectivore

Todirostrum sylvia Tyrannidae Insectivore

Tolmomyias sulphurescens Tyrannidae Insectivore-frugivore

Leptopogon superciliaris Tyrannidae Insectivore-frugivore

Leptopogon rufipectus Tyrannidae Insectivore-frugivore

Leptopogon amaurocephalus Tyrannidae Insectivore-frugivore

Phylloscartes ophtalmicus Tyrannidae Insectivore

Phylloscartes poecilotis Tyrannidae Insectivore

Myiodynastes maculatus Tyrannidae Insectivore-frugivore

Myiozetetes cayanensis Tyrannidae Insectivore-frugivore

Myiozetetes similis Tyrannidae Insectivore-frugivore

Empidonax sp Tyrannidae Insectivore

Contopus sp Tyrannidae Insectivore

Phyllomyias griseiceps Tyrannidae Insectivore

Phyllomyias nigrocapillus Tyrannidae Insectivore

Continued

214


Phaeomyias murina Tyrannidae Insectivore

Pitangus sulphuratus Tyrannidae Insectivore-frugivore

Myiobus atricaudus Tyrannidae Insectivore

Myiarchus apicalis Tyrannidae Insectivore-frugivore

Polioptila plumbea Polioptilidae Insectivore

Vireo olivaceus Vireonidae Frugivore-insectivore

Vireo leucophrys Vireonidae Frugivore-insectivore

Hylophilus decurtatus Vireonidae Insectivore-frugivore

Hylophilus flavipes Vireonidae Insectivore-frugivore

Hylophilus semibrunneus Vireonidae Insectivore-frugivore

Vireo flavifrons Vireonidae Frugivore-insectivore

Cyclarhis nigrirostris Vireonidae Frugivore-insectivore

Cyclarhis gujanensis Vireonidae Frugivore-insectivore

Icterus chrysater Icteridae Frugivore

Icterus galbula Icteridae Frugivore

Icterus nigrogularis Icteridae Frugivore

Cacicus chrysonotus Icteridae Frugivore

Psaracolius decumanus Icteridae Frugivore

Molothrus oryzibora Icteridae Frugivore-granivore

Mniotilta varia Parulidae Insectivore

Dendroica fusca Parulidae Insectivore

Continued

215


Vermivora peregrina Parulidae Insectivore

Vermivora chrysoptera Parulidae Insectivore

Dendroica petechia Parulidae Insectivore

Dendroica castanea Parulidae Insectivore

Dendroica cerulea Parulidae Insectivore

Parula pitiayumi Parulidae Insectivore

Wilsonia canadensis Parulidae Insectivore

Oporornis philadephia Parulidae Insectivore

Setophaga ruticilla Parulidae Insectivore

Basileuterus culicivorus Parulidae Insectivore

Basileuterus coronatus Parulidae Insectivore

Basileuterus tristriatus Parulidae Insectivore

Basileuterus rufifrons Parulidae Insectivore

Basileuterus cinereicollis Parulidae Insectivore

Basileuterus luteoviridis Parulidae Insectivore

Myioborus miniatus Parulidae Insectivore

Myioborus ornatus Parulidae Insectivore

Coereba flaveola Incertae sedis Nectarivore

Piranga rubra Cardinalidae Frugivore-insectivore

Piranga olivacea Cardinalidae Frugivore-insectivore

Anisognathus lacrymosus Thraupidae Frugivore

Continued

216


Anisognathus somptuosus Thraupidae Frugivore

Chlorospingus flavigularis Incertae sedis Frugivore

Chlorospingus ophthalmicus Incertae sedis Frugivore

Chlorospingus canigularis Incertae sedis Frugivore

Dacnis cayana Thraupidae Frugivore-insectivore

Dacnis hartlaubi Thraupidae Frugivore-insectivore

Dacnis lineata Thraupidae Frugivore-insectivore

Cyanerpes caeruleus Thraupidae Omnivore

Chlorophonia cyanea Thraupidae Frugivore

Conirostrum speciosum Thraupidae Nectarivore-insectivore

Conirostrum albifrons Thraupidae Nectarivore-insectivore

Tachyphonus rufus Thraupidae Frugivore

Tachyphonus luctuosus Thraupidae Frugivore

Hemispingus superciliaris Thraupidae Frugivore

Hemispingus atropileus Thraupidae Frugivore

Cnemoscopus rubrirostris Thraupidae Frugivore

Chlorornis riefferii Thraupidae Frugivore

Chlorophanes spiza Thraupidae Frugivore-nectarivore

Thlypopsis fulviceps Thraupidae Frugivore

Pipraeidea melanonota Thraupidae Frugivore

Rhodinocichla rosea Thraupidae Omnivore

Continued

217


Pheucticus ludovicianus Cardinalidae Frugivore-insectivore

Arremonops conirostris Emberizidae Granivore

Arremon schlegeli Emberizidae Omnivore

Atlapetes gutturalis Cardinalidae Frugivore

Atlapetes semirufus Cardinalidae Frugivore

Atlapetes latinuchus Cardinalidae Frugivore

Atlapetes rufinuchus Cardinalidae Frugivore

Atlapetes schistaseus Cardinalidae Frugivore

Cyanocompsa brissoni Cardinalidae Frugivore-insectivore

Arremon brunneinucha Emberizidae Omnivore

Arremon torquatus Emberizidae Omnivore

Carduelis psaltria Fringillidae Granivore

Tiaris olivaceus Incertae sedis Granivore

Tiaris fuliginosus Incertae sedis Granivore

Sporophila nigricollis Emberizidae Granivore

Volatinia jacarina Emberizidae Granivore

218

App

endi

x E

. Cha

ract

eris

tics o

f 84

1-km

2 pix

els s

urve

yed

in 1

1 di

ffer

ent r

egio

ns in

the

And

es in

Col

ombi

a, E

cuad

or a

nd P

eru.

Win

terin

g se

ason

s 200

7-20

10.

Loc

ality

ID C

ode

Pred

omin

ant

habi

tat

No.

tree

s/ha

Bas

al

area

m2/

ha

Hei

ght

(m)

%

cano

py

cove

r

%

Gro

und

cove

r

Ave

rage

Shru

b

dens

ity

%

Fore

st

cove

r

per

pixe

l

Lon

g.

Lat

. E

leva

tion

(m)

Agu

achi

ca

Ran

dom

Cen

ter (

124)

Se

cond

ary

fore

st

205.

92

4.86

5.

92

41.6

7 35

.83

6.42

45

.25

-73.

496

8.32

1 77

7

Agu

achi

ca

Ran

dom

Eas

t (12

4)

Seco

ndar

y fo

rest

65

..895

2.

68

9.11

17

.50

47.5

0 3.

17

48.6

7 -7

3.49

6 8.

303

1246

Agu

achi

ca

Ran

dom

Nor

th (1

24)

Seco

ndar

y fo

rest

61

.78

2.97

9.

87

31.6

7 41

.67

6.00

31

.67

-73.

496

8.34

1 91

2

Agu

achi

ca

Ran

dom

Sou

th (1

24)

Seco

ndar

y fo

rest

18

1.21

11

.99

11.8

1 32

.50

16.6

7 1.

67

38.1

7 -7

3.51

4 8.

321

589

Agu

achi

ca

Ran

dom

Wes

t (12

4)

Seco

ndar

y fo

rest

49

.42

3.94

9.

33

19.1

7 0.

00

0.00

32

.33

-73.

478

8.32

1 54

9

Agu

achi

ca

Paire

d C

ente

r (12

4)

Silv

opas

ture

s 13

5.91

7.

99

11.1

6 60

.83

5.83

5.

50

23.0

0 -7

3.47

8 8.

338

1021

Agu

achi

ca

Paire

d Ea

st (1

24)

Succ

essi

onal

49

0.09

11

.89

12.7

5 47

.50

40.0

0 14

.00

39.1

7 -7

3.46

0 8.

338

1676

Agu

achi

ca

Paire

d N

orth

(124

) Se

cond

ary

fore

st

135.

91

3.10

10

.88

24.1

7 51

.67

17.5

8 31

.83

-73.

478

8.35

6 13

74

Agu

achi

ca

Paire

d So

uth

(124

) Se

cond

ary

fore

st

333.

59

7.24

8.

47

64.1

7 39

.17

12.1

7 46

.00

-73.

469

8.32

1 12

83

Agu

achi

ca

Paire

d W

est (

124)

Sh

ade

coff

ee

193.

57

5.59

8.

00

52.5

0 38

.33

4.17

39

.83

-73.

496

8.34

7 89

0

cont

inue

d

218

219

App

endi

x E.

(con

tinue

d)

Sn

J. d

e la

Mon

taña

R

ando

m E

ast (

216)

Sh

ade

coff

ee

177.

09

5.02

5.

79

53.3

3 61

.67

9.33

63

.43

-75.

728

7.00

4 15

40

Sn J.

de

la

Mon

taña

R

ando

m N

orth

(216

) Se

cond

ary

fore

st

271.

82

11.1

0 6.

87

55.8

3 51

.67

12.3

3 46

.00

-75.

746

7.02

2 10

57

Sn J.

de

la

Mon

taña

Pa

ired

Wes

t (21

6)

Seco

ndar

y fo

rest

45

3.03

12

.16

8.82

60

.83

75.0

0 11

.33

70.2

9 -7

5.74

0 7.

004

1159

Sn V

de

chuc

urí

Ran

dom

Cen

ter (

231)

M

atur

e fo

rest

26

3.58

6.

18

9.81

50

.00

75.8

3 11

.17

51.0

0 -7

3.37

9 6.

812

2036

Sn V

de

chuc

urí

Ran

dom

Eas

t (23

1)

Mat

ure

fore

st

218.

28

5.95

9.

79

62.5

0 72

.50

8.42

57

.57

-73.

361

6.81

2 22

16

Sn V

de

chuc

urí

Ran

dom

Nor

th (2

31)

Seco

ndar

y fo

rest

28

4.17

12

.90

8.70

72

.50

59.1

7 15

.50

68.2

9 -7

3.37

9 4.

831

1292

Sn V

de

chuc

urí

Ran

dom

Wes

t (23

1)

Seco

ndar

y fo

rest

30

4.76

9.

40

12.5

6 53

.33

70.0

0 12

.50

65.0

0 -7

3.39

7 6.

812

1817

Sn V

de

chuc

urí

Paire

d C

ente

r (23

1)

Mat

ure

fore

st

539.

51

123.

53

20.8

9 77

.50

76.6

7 15

.83

66.4

3 -7

3.36

0 6.

852

1926

cont

inue

d

219

220

App

endi

x E.

(con

tinue

d)

Sn

V d

e

chuc

urí

Paire

d Ea

st (2

31)

Mat

ure

fore

st

378.

90

41.2

1 8.

47

49.1

7 47

.50

8.42

26

.57

-73.

342

6.85

8 24

50

Sn V

de

chuc

urí

Paire

d N

orth

(231

) M

atur

e fo

rest

31

7.12

47

.64

7.70

66

.67

65.0

0 19

.83

68.1

4 -7

3.35

8 6.

871

1962

Sn V

de

chuc

urí

Paire

d So

uth

(231

) M

atur

e fo

rest

51

4.80

15

7.57

21

.33

75.0

0 65

.83

16.5

8 42

.43

-73.

363

6.84

1 20

20

Sn V

de

chuc

urí

Paire

d W

est (

231)

Se

cond

ary

fore

st

576.

58

128.

10

6.43

69

.17

49.1

7 21

.92

49.5

7 -7

3.37

8 6.

852

1681

Chi

cam

ocha

R

ando

m C

ente

r (24

8)

Silv

opas

ture

s 24

.71

0.78

4.

20

15.0

0 8.

33

9.50

5.

25

-72.

821

6.54

6 84

2

Chi

cam

ocha

R

ando

m E

ast (

248)

Su

cces

sion

al

543.

63

6.67

4.

84

34.1

7 0.

00

13.9

2 19

.71

-72.

803

6.54

6 99

5

Chi

cam

ocha

R

ando

m N

orth

(248

) Su

cces

sion

al

32.9

5 0.

98

4.56

12

.50

31.6

7 6.

25

13.4

3 -7

2.82

1 6.

563

1364

Chi

cam

ocha

R

ando

m S

outh

(248

) Si

lvop

astu

res

242.

99

6.95

6.

55

25.0

0 2.

50

14.3

3 19

.57

-72.

821

6.52

8 10

68

Chi

cam

ocha

R

ando

m W

est (

248)

Su

cces

sion

al

0.00

0.

00

0.00

3.

33

0.00

12

.33

6.71

-7

2.83

8 6.

546

1169

Chi

cam

ocha

Pa

ired

Cen

ter (

248)

Su

cces

sion

al

0.00

0.

00

0.00

0.

00

0.00

15

.00

15.0

0 -7

2.82

1 6.

555

1251

Chi

cam

ocha

Pa

ired

East

(248

) Si

lvop

astu

res

263.

58

9.10

5.

13

28.3

3 1.

67

5.42

19

.86

-72.

803

6.55

5 11

25

Chi

cam

ocha

Pa

ired

Nor

th (2

48)

Succ

essi

onal

49

.42

0.50

4.

00

15.8

3 45

.00

15.5

0 19

.29

-72.

821

6.57

2 12

65

Chi

cam

ocha

Pa

ired

Sout

h (2

48)

Silv

opas

ture

s 94

.72

12.6

8 8.

50

42.5

0 24

.17

9.50

9.

71

-72.

821

6.53

7 95

7

cont

inue

d

220

221

App

endi

x E.

(con

tinue

d)

Pa

cora

,

Abe

jorr

al

Paire

d C

ente

r (30

7)

Shad

e co

ffee

15

6.50

4.

50

6.36

55

.00

50.0

0 10

.42

29.1

4 -7

5.50

6 5.

561

1288

Paco

ra,

Abe

jorr

al

Paire

d Ea

st (3

07)

Succ

essi

onal

13

8.38

4.

80

6.39

57

.00

46.0

0 10

.10

19.0

0 -7

5.48

8 5.

561

1250

Paco

ra,

Abe

jorr

al

Paire

d N

orth

(307

) Se

cond

ary

fore

st

160.

62

3.05

6.

47

58.3

3 48

.33

10.5

0 34

.00

-75.

506

5.57

9 11

32

Paco

ra,

Abe

jorr

al

Paire

d W

est (

307)

Si

lvop

astu

res

205.

92

5.02

5.

56

65.0

0 56

.67

13.0

0 24

.00

-75.

524

5.56

1 10

82

Paya

,

Boy

acá

Ran

dom

Cen

ter (

314)

Se

cond

ary

fore

st

617.

76

17.4

1 9.

54

65.8

3 24

.17

35.5

0 45

.50

-72.

496

5.60

4 13

74

Paya

,

Boy

acá

Ran

dom

Eas

t (31

4)

Shad

e co

ffee

12

7.67

7.

30

9.33

45

.83

64.1

7 4.

42

29.5

0 -7

2.47

8 5.

604

1325

Paya

,

Boy

acá

Ran

dom

Nor

th (3

14)

Succ

essi

onal

14

8.26

5.

66

6.91

50

.00

71.6

7 9.

42

37.0

0 -7

2.49

6 5.

622

1770

Paya

,

Boy

acá

Ran

dom

Sou

th (3

14)

Silv

opas

ture

s 25

1.22

9.

21

9.57

67

.50

71.6

7 11

.25

58.8

3 -7

2.49

6 5.

586

2179

cont

inue

d

221

222

App

endi

x E.

(con

tinue

d)

Pa

ya,

Boy

acá

Ran

dom

Wes

t (31

4)

Succ

essi

onal

49

0.09

27

.06

14.6

9 74

.17

74.1

7 35

.42

71.8

3 -7

2.51

4 5.

604

1500

Paya

,

Boy

acá

Paire

d C

ente

r (31

4)

Seco

ndar

y fo

rest

20

5.92

7.

28

11.7

9 47

.50

91.6

7 14

.83

32.5

0 -7

2.52

3 5.

631

1998

Paya

,

Boy

acá

Paire

d Ea

st (3

14)

Seco

ndar

y fo

rest

16

8.86

5.

11

7.15

65

.83

63.3

3 13

.50

65.1

7 -7

2.50

5 5.

631

1951

Pa

ya,

Boy

acá

Paire

d N

orth

(314

) Se

cond

ary

fore

st

210.

04

2.38

8.

32

38.3

3 96

.67

36.4

2 26

.00

-72.

523

5.64

9 20

77

Paya

,

Boy

acá

Paire

d So

uth

(314

) Su

cces

sion

al

164.

74

5.77

8.

26

37.5

0 73

.33

8.58

54

.67

-72.

541

5.63

1 21

75

Paya

,

Boy

acá

Paire

d W

est (

314)

Se

cond

ary

fore

st

313.

00

15.4

2 11

.93

38.3

3 82

.50

11.3

3 49

.67

-72.

523

5.61

3 20

96

Ibag

ué

Ran

dom

Cen

ter (

395)

Se

cond

ary

fore

st

247.

11

15.6

3 13

.60

42.5

0 59

.17

1.83

14

.20

-75.

012

4.50

4 58

6

Ibag

ué

Ran

dom

Eas

t (39

5)

Silv

opas

ture

s 32

9.47

6.

75

8.90

43

.33

65.0

0 3.

67

17.1

4 -7

4.99

4 4.

504

567

Ibag

ué

Ran

dom

Nor

th (3

95)

Seco

ndar

y fo

rest

16

8.86

16

.42

16.3

6 61

.67

55.8

3 31

.58

14.2

9 -7

5.01

3 4.

522

657

Ibag

ué

Ran

dom

Sou

th (3

95)

Seco

ndar

y fo

rest

12

7.67

7.

21

6.45

18

.33

60.8

3 12

.08

12.8

6 -7

5.01

2 4.

486

619

cont

inue

d

222

223

App

endi

x E.

(con

tinue

d)

Ib

agué

R

ando

m W

est (

395)

Se

cond

ary

fore

st

300.

65

13.4

8 8.

34

45.8

3 45

.83

23.2

5 16

.71

-75.

030

4.52

1 65

6

Ibag

ué

Paire

d C

ente

r (39

5)

Succ

essi

onal

11

9.43

17

.14

6.32

37

.50

66.6

7 16

.58

14.1

4 -7

5.01

3 4.

477

624

Ibag

ué

Paire

d Ea

st (3

95)

Silv

opas

ture

s 40

7.72

20

.94

8.91

50

.00

59.1

7 30

.25

15.7

1 -7

4.99

5 4.

477

595

Ibag

ué

Paire

d N

orth

(395

) Si

lvop

astu

res

115.

32

15.8

6 7.

98

30.0

0 55

.83

31.0

0 17

.14

-75.

013

4.49

5 59

1

Ibag

ué

Paire

d So

uth

(395

) Se

cond

ary

fore

st

226.

51

12.0

1 8.

09

50.8

3 67

.50

22.5

0 17

.00

-75.

011

4.48

6 61

9

Ibag

ué

Paire

d W

est (

395)

Se

cond

ary

fore

st

634.

24

19.9

1 8.

64

45.0

0 56

.67

28.1

7 14

.57

-75.

028

4.47

7 64

3

Ros

as, C

auca

R

ando

m C

ente

r (56

1)

Shad

e co

ffee

61

.78

1.94

7.

33

35.0

0 64

.17

18.0

8 57

.75

-76.

737

2.22

9 16

64

Ros

as, C

auca

R

ando

m E

ast (

561)

Sh

ade

coff

ee

185.

33

4.90

6.

39

68.3

3 44

.17

10.5

8 72

.00

-76.

720

2.22

9 17

09

Ros

as, C

auca

R

ando

m N

orth

(561

) Sh

ade

coff

ee

41.1

8 1.

22

7.13

25

.83

61.6

7 3.

83

61.4

3 -7

6.73

7 2.

247

1794

Ros

as, C

auca

R

ando

m S

outh

(561

) Sh

ade

coff

ee

247.

11

7.79

6.

90

57.5

0 50

.83

15.6

7 67

.29

-76.

737

2.21

2 18

33

Ros

as, C

auca

R

ando

m W

est (

561)

Sh

ade

coff

ee

271.

82

13.3

7 7.

85

56.6

7 31

.67

17.6

7 54

.71

-76.

755

2.22

9 12

48

Ros

as, C

auca

Pa

ired

Cen

ter (

561)

M

atur

e fo

rest

32

1.24

23

.20

9.00

73

.75

42.5

0 18

.13

39.8

6 -7

6.68

8 2.

213

2376

Ros

as, C

auca

Pa

ired

East

(561

) Se

cond

ary

fore

st

255.

34

18.4

9 8.

49

55.0

0 35

.00

20.3

3 68

.71

-76.

670

2.21

3 13

86

Patia

, Cau

ca

Ran

dom

Cen

ter (

581)

Se

cond

ary

fore

st

148.

26

4.42

4.

98

44.1

7 68

.33

6.67

14

.80

-77.

171

1.98

8 58

1

Patia

, Cau

ca

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dom

Eas

t (58

1)

Silv

opas

ture

s 11

9.43

4.

11

6.17

45

.83

50.0

0 3.

25

15.5

7 -7

7.15

3 1.

988

595

Patia

, Cau

ca

Ran

dom

Wes

t (58

1)

Silv

opas

ture

s 22

2.40

14

.16

8.10

72

.50

57.5

0 12

.17

18.8

6 -7

7.18

8 1.

988

554

Patia

, Cau

ca

Ran

dom

Nor

th (5

81)

Silv

opas

ture

s 14

8.26

7.

88

6.07

39

.17

81.6

7 7.

08

17.5

7 -7

7.17

1 2.

005

575

cont

inue

d

223

224

App

endi

x E.

(con

tinue

d)

Pa

tia, C

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ando

m S

outh

(581

) Se

cond

ary

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st

177.

09

4.02

5.

91

63.3

3 51

.67

12.8

3 18

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-77.

171

1.97

0 57

5

Patia

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ca

Paire

d C

ente

r (58

1)

Silv

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ture

s 53

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3.63

7.

04

38.0

0 59

.00

8.70

17

.86

-77.

144

1.97

0 57

9

Patia

, Cau

ca

Paire

d Ea

st (5

81)

Silv

opas

ture

s 24

7.11

10

.37

4.90

44

.17

61.6

7 2.

67

10.2

9 -7

7.12

7 1.

970

611

Patia

, Cau

ca

Paire

d N

orth

(581

) Se

cond

ary

fore

st

267.

70

5.73

5.

98

64.1

7 44

.17

4.92

18

.86

-77.

144

1.98

8 59

3

Patia

, Cau

ca

Paire

d So

uth

(581

) Su

cces

sion

al

107.

08

2.73

5.

31

33.3

3 76

.67

17.1

7 16

.86

-77.

144

1.95

2 60

5

Patia

, Cau

ca

Paire

d W

est (

581)

Se

cond

ary

fore

st

304.

76

7.67

6.

14

70.0

0 54

.17

6.67

15

.14

-77.

162

1.97

0 58

6

P.N

San

gay

Ran

dom

Cen

ter (

667)

M

atur

e fo

rest

54

9.89

11

5.01

16

.60

78.3

3 58

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37.2

5 18

.00

-78.

090

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76

1000

P.N

San

gay

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dom

Eas

t (66

7)

Mat

ure

fore

st

731.

36

36.4

1 17

.47

75.0

0 61

.67

41.0

0 76

.86

-78.

073

-1.6

76

885

P.N

San

gay

Ran

dom

Nor

th (6

67)

Mat

ure

fore

st

964.

68

37.6

0 19

.30

78.3

3 59

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39.0

8 75

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-78.

090

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59

1238

P.N

San

gay

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dom

Sou

th (6

67)

Mat

ure

fore

st

988.

46

75.9

7 17

.87

75.8

3 60

.00

34.5

0 66

.00

-78.

090

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87

1035

P.N

San

gay

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d C

ente

r (66

7)

Mat

ure

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st

685.

01

41.3

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62.5

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36.9

2 65

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-78.

111

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51

1083

P.N

San

gay

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st (6

67)

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ure

fore

st

824.

64

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0 23

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7 53

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8 65

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-78.

101

-1.6

51

1045

P.N

San

gay

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d N

orth

(667

) M

atur

e fo

rest

66

3.83

41

.27

21.0

0 43

.33

47.5

0 43

.33

65.4

4 -7

8.11

1 -1

.640

10

44

P.N

San

gay

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d So

uth

(667

) M

atur

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rest

54

4.11

12

9.21

27

.11

46.6

7 36

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3 65

.44

-78.

111

-1.6

57

1234

P.N

San

gay

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d W

est (

667)

M

atur

e fo

rest

80

2.61

40

.68

22.9

8 50

.00

54.1

7 60

.67

65.4

4 -7

8.11

4 -1

.651

11

80

Chi

ngoz

ales

R

ando

m N

orth

(734

) Se

cond

ary

fore

st

457.

15

47.2

8 17

.12

85.0

0 92

.50

39.0

0 66

.67

-78.

679

-4.9

06

1350

Chi

ngoz

ales

R

ando

m S

outh

(734

) M

atur

e fo

rest

35

8.30

3.

94

8.00

50

.00

87.5

0 78

.00

79.0

0 -7

8.68

2 -4

.942

15

80

Chi

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R

ando

m W

est (

734)

M

atur

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rest

88

9.58

36

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18.8

9 10

0.00

90

.00

0.00

74

.50

-78.

692

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19

1080

224

225

App

endi

x F.

Neo

tropi

cal-N

earc

tic m

igra

tory

bird

s and

mix

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es fl

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attr

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es re

cord

ed in

1-k

m2 p

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s (84

and

39

pixe

ls,

resp

ectiv

ely)

in 1

1 di

ffer

ent r

egio

ns in

the

And

es in

Col

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a, E

cuad

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nd P

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Win

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g se

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s 200

7-20

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Loc

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ID

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TM

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NT

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k ri

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k si

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Floc

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coun

ter

rate

Agu

achi

ca

Ran

dom

Cen

ter (

124)

0.

39 ±

0.0

1 0.

52 ±

0.0

4 6

± 2.

83

19 ±

18.

38

0.39

± 1

Agu

achi

ca

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Eas

t (12

4)

0.64

± 0

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2.56

± 0

.01

- -

-

Agu

achi

ca

Ran

dom

Nor

th (1

24)

0.67

± 0

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2.67

± 0

.1

- -

-

Agu

achi

ca

Ran

dom

Sou

th (1

24)

0.46

± 0

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1.37

± 0

.02

- -

-

Agu

achi

ca

Ran

dom

Wes

t (12

4)

0.46

± 0

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1.03

± 0

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7.5

± 6.

36

10 ±

9.9

0.

23 ±

0.5

7

Agu

achi

ca

Paire

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ente

r (12

4)

1.14

± 0

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1.94

± 0

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11

17

0.11

± 0

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Agu

achi

ca

Paire

d Ea

st (1

24)

0.40

± 0

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1.00

± 0

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8.5

± 0.

71

12.5

± 0

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0.2

± 1.

15

Agu

achi

ca

Paire

d N

orth

(124

) 0.

15 ±

0.0

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0.0

5 7

11

0.15

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.57

Agu

achi

ca

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(124

) 0.

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0.0

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9 0.

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8

Agu

achi

ca

Paire

d W

est (

124)

0.

76 ±

0.0

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0.0

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± 2.

83

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22 ±

0.7

6

San

J. de

la M

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dom

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t (21

6)

2.00

± 0

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3.00

± 0

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-

Con

tinue

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225

226

App

endi

x F.

(con

tinue

d)

Sa

n J.

de la

Mon

taña

R

ando

m N

orth

(216

) 0.

73 ±

0.0

2 1.

45 ±

0.0

5 -

- -

San

J. de

la M

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Paire

d W

est (

216)

0.

62 ±

0.0

2 3.

40 ±

0.1

-

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San

V d

e ch

ucur

í R

ando

m C

ente

r (23

1)

0.42

± 0

.01

0.73

± 0

.02

12

46

0.10

± 0

.35

San

V d

e ch

ucur

í R

ando

m E

ast (

231)

0.

80 ±

0.0

3 2.

93 ±

0.1

2 14

32

0.

13 ±

0.3

2

San

V d

e ch

ucur

í R

ando

m N

orth

(231

) 0.

47 ±

0.0

2 1.

18 ±

0.0

5 10

± 2

.52

13.5

± 5

.13

0.24

± 0

.67

San

V d

e ch

ucur

í R

ando

m W

est (

231)

2.

71 ±

0.0

5 11

.23

± 2.

28

13.3

3 ±

7.31

35

.67

± 12

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1.16

± 0

.55

San

V d

e ch

ucur

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ired

Cen

ter (

231)

0.

36 ±

0.0

2 0.

87 ±

0.0

9 -

- -

San

V d

e ch

ucur

í Pa

ired

East

(231

) 0.

42 ±

0.0

3 0.

76 ±

0.0

4 -

- -

San

V d

e ch

ucur

í Pa

ired

Nor

th (2

31)

0.26

± 0

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0.71

± 0

.05

- -

-

San

V d

e ch

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í Pa

ired

Sout

h (2

31)

0.33

± 0

.04

0.85

± 0

.02

- -

-

San

V d

e ch

ucur

í Pa

ired

Wes

t (23

1)

0.35

± 0

.01

1.05

± 0

.11

- -

-

Ric

aute

R

ando

m C

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r (24

8)

0.13

± 0

.01

0.13

± 0

.03

0 0

0

Ric

aute

R

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m E

ast (

248)

-

- 0

0 0

Con

tinue

d

226

227

App

endi

x F.

(con

tinue

d)

R

icau

te

Ran

dom

Nor

th (2

48)

- -

0 0

0

Ric

aute

R

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m S

outh

(248

) -

- 3

5 0.

4 ±

0.29

Ric

aute

R

ando

m W

est (

248)

-

- 0

0 0

Ric

aute

Pa

ired

Cen

ter (

248)

-

- 0

0 0

Ric

aute

Pa

ired

East

(248

) 0.

40 ±

0.0

2 0.

40 ±

0.0

5 3

4 0.

4 ±

0.47

Ric

aute

Pa

ired

Nor

th (2

48)

- -

0 0

0

Ric

aute

Pa

ired

Sout

h (2

48)

- -

7 14

0.

24 ±

0.7

2

Paco

ra, A

bejo

rral

Pa

ired

Cen

ter (

307)

0.

92 ±

0.0

2 3.

76 ±

0.0

6 -

- -

Paco

ra, A

bejo

rral

Pa

ired

East

(307

) 1.

28 ±

0.0

1 1.

37 ±

0.0

1 2.

5 ±

0.71

7

± 1.

41

0.23

± 0

.45

Paco

ra, A

bejo

rral

Pa

ired

Nor

th (3

07)

0.76

± 0

.03

3.29

± 0

.13

19.2

± 6

.05

9.27

± 1

3.05

1.

15 ±

2.6

5

Paco

ra, A

bejo

rral

Pa

ired

Wes

t (30

7)

0.60

± 0

.03

3.72

± 0

.02

- -

-

Paya

, Boy

acá

Ran

dom

Cen

ter (

314)

0.

50 ±

0.0

2 0.

74 ±

0.0

3 -

- -

Paya

, Boy

acá

Ran

dom

Eas

t (31

4)

0.86

± 0

.01

1.51

± 0

.1

8 17

0.

11 ±

0.2

5

Con

tinue

d

227

228

App

endi

x F.

(con

tinue

d)

Pa

ya, B

oyac

á R

ando

m N

orth

(314

) 0.

64 ±

0.0

5 3.

43 ±

0.1

5 8

± 2

16 ±

4.3

6 0.

32 ±

0.8

7

Paya

, Boy

acá

Ran

dom

Sou

th (3

14)

0.11

± 0

.04

0.78

± 0

.05

6 12

0.

11 ±

0.5

Paya

, Boy

acá

Ran

dom

Wes

t (31

4)

- -

6 ±

10 ±

0.

21 ±

0.2

9

Paya

, Boy

acá

Paire

d C

ente

r (31

4)

0.58

± 0

.01

0.87

± 0

.4

- -

-

Paya

, Boy

acá

Paire

d Ea

st (3

14)

0.19

± 0

.02

0.38

± 0

.04

4.75

± 2

.13

7.75

± 2

.02

0.29

± 0

.87

Paya

, Boy

acá

Paire

d N

orth

(314

) 0.

19 ±

0.0

2 0.

19 ±

0.0

5 6

17

0.09

± 0

.35

Paya

, Boy

acá

Paire

d So

uth

(314

) 0.

63 ±

0.0

3 1.

88 ±

0.0

2 6.

5 ±

1.41

10

.5 ±

4.2

8 0.

38 ±

0.8

9

Paya

, Boy

acá

Paire

d W

est (

314)

-

- -

- -

Ibag

ué

Ran

dom

Cen

ter (

395)

0.

16 ±

0.0

1 0.

16 ±

0.0

5 6.

5 ±

2.25

6.

5 ±

4.82

0.

32 ±

0.5

9

Ibag

ué

Ran

dom

Eas

t (39

5)

0.57

± 0

.04

1.33

± 0

.07

- -

-

Ibag

ué

Ran

dom

Nor

th (3

95)

0.30

± 0

.02

0.40

± 0

.04

- -

-

Ibag

ué

Ran

dom

Sou

th (3

95)

- -

- -

-

Ibag

ué

Ran

dom

Wes

t (39

5)

0.53

± 0

.01

1.37

± 0

.08

- -

-

Con

tinue

d

228

229

App

endi

x F.

(con

tinue

d)

Ib

agué

Pa

ired

Cen

ter (

395)

0.

42 ±

0.0

1 0.

74 ±

0.0

4 -

- -

Ibag

ué

Paire

d Ea

st (3

95)

0.30

± 0

.03

1.61

± 0

.09

- -

-

Ibag

ué

Paire

d N

orth

(395

) 0.

24 ±

0.0

2 0.

49 ±

0.0

1 -

- -

Ibag

ué

Paire

d So

uth

(395

) 0.

40 ±

0.0

1 0.

40 ±

0.0

2 -

- -

Ibag

ué

Paire

d W

est (

395)

0.

51 ±

0.0

2 1.

20 ±

0.0

4 -

- -

Ros

as, C

auca

R

ando

m C

ente

r (56

1)

0.53

± 0

.04

6.02

± 0

.02

14

31

0.18

± 0

.45

Ros

as, C

auca

R

ando

m E

ast (

561)

0.

83 ±

0.0

5 0.

83 ±

0.0

3 8.

23 ±

4.5

5 13

.85

± 8.

73

1.52

± 2

.08

Ros

as, C

auca

R

ando

m N

orth

(561

) 0.

21 ±

0.0

1 1.

71 ±

0.0

5 -

- -

Ros

as, C

auca

R

ando

m S

outh

(561

) 0.

53 ±

0.0

1 2.

63 ±

0.0

7 9.

78 ±

2.1

1 16

± 4

.47

0.95

± 1

.73

Ros

as, C

auca

R

ando

m W

est (

561)

1.

14 ±

0.0

6 3.

73 ±

0.0

8 9.

67 ±

4.6

3 15

± 6

.07

0.97

± 1

.73

Ros

as, C

auca

Pa

ired

Cen

ter (

561)

-

- -

- -

Ros

as, C

auca

Pa

ired

East

(561

) 0.

75 ±

0.0

4 1.

00 ±

0.0

7 -

- -

Patia

, Cau

ca

Ran

dom

Cen

ter (

581)

1.

75 ±

0.0

5 5.

00 ±

0.0

3 -

- -

Con

tinue

d

229

230

App

endi

x F.

(con

tinue

d)

Pa

tia, C

auca

R

ando

m E

ast (

581)

0.

55 ±

0.0

2 3.

45 ±

0.0

2 -

- -

Patia

, Cau

ca

Ran

dom

Wes

t (58

1)

1.60

± 0

.01

6.40

± 0

.1

- -

-

Patia

, Cau

ca

Ran

dom

Nor

th (5

81)

0.60

± 0

.04

6.00

± 0

.12

- -

-

Patia

, Cau

ca

Ran

dom

Sou

th (5

81)

1.33

± 0

.05

6.33

± 0

.04

- -

-

Patia

, Cau

ca

Paire

d C

ente

r (58

1)

0.89

± 0

.01

3.56

± 0

.08

- -

-

Patia

, Cau

ca

Paire

d Ea

st (5

81)

2.00

± 0

.04

9.33

± 0

.05

- -

-

Patia

, Cau

ca

Paire

d N

orth

(581

) 1.

00 ±

0.0

5 1.

75 ±

0.0

7 -

- -

Patia

, Cau

ca

Paire

d So

uth

(581

) 0.

14 ±

0.0

3 0.

43 ±

0.0

1 -

- -

Patia

, Cau

ca

Paire

d W

est (

581)

1.

00 ±

0.0

4 6.

40 ±

0.0

4 -

- -

P.N

San

gay

Ran

dom

Cen

ter (

667)

0.

16 ±

0.0

2 0.

16 ±

0.0

3 4.

67 ±

0.5

7 12

± 4

.36

0.25

± 0

.29

P.N

San

gay

Ran

dom

Eas

t (66

7)

0.08

± 0

.01

0.08

± 0

.01

- -

-

P.N

San

gay

Ran

dom

Nor

th (6

67)

0.08

± 0

.02

0.08

± 0

.01

- -

-

P.N

San

gay

Ran

dom

Sou

th (6

67)

- -

5.33

± 1

.53

13.3

3 ±

4.73

0.

25 ±

0.2

Con

tinue

d

230

231

App

endi

x F.

(con

tinue

d)

P.

N S

anga

y Pa

ired

Cen

ter (

667)

-

- 9

13

0.08

± 0

.42

P.N

San

gay

Paire

d Ea

st (6

67)

0.15

± 0

.04

0.15

± 0

.02

8 19

0.

08 ±

0.3

5

P.N

San

gay

Paire

d N

orth

(667

) 0.

15 ±

0.0

1 0.

30 ±

0.0

1 -

- -

P.N

San

gay

Paire

d So

uth

(667

) 0.

15 ±

0.0

1 0.

15 ±

0.0

4 -

- -

P.N

San

gay

Paire

d W

est (

667)

-

- -

- -

Chi

ngoz

ales

R

ando

m N

orth

(734

) -

- -

- -

Chi

ngoz

ales

R

ando

m S

outh

(734

) -

- 4

7 0.

21 ±

0.4

Chi

ngoz

ales

R

ando

m W

est (

734)

0.

13 ±

0.0

1 0.

13 ±

0.0

2 -

- -

231

232

App

endi

x G

. Coe

ffic

ient

s of t

op-r

anke

d re

gres

sion

mod

els r

elat

ing

flock

rich

ness

and

abu

ndan

ce a

ttrib

utes

and

env

ironm

enta

l

varia

bles

in th

e A

ndes

. Sta

tistic

s inc

lude

mod

el e

stim

ates

, the

stan

dard

err

ors (

SE) a

nd t-

stat

istic

. Ana

lysi

s bas

ed o

n 39

1-k

m2 p

ixel

s.

Para

met

ers

Estim

ate

SE

t P

Floc

k ri

chne

ss =

hab

itat t

ype

+ lo

cal s

truc

ture

+ fo

rest

cov

er +

inte

ract

ions

Inte

rcep

t 34

.034

9.

621

3.53

7 0.

002

Hab

itat (

Past

ures

with

isol

ated

tree

s)

-20.

449

10.2

55

-1.9

94

0.06

1

Hab

itat (

Seco

ndar

y fo

rest

) -2

5.86

1 9.

864

-2.6

22

0.01

7

Hab

itat (

Shad

e co

ffee

) -6

.495

16

.345

-0

.397

0.

696

Hab

itat (

Succ

essi

onal

) -3

4.79

5 10

.132

-3

.434

0.

003

Fore

st c

over

-0

.384

0.

165

-2.3

27

0.03

1

Loca

l stru

ctur

e -6

.622

2.

318

-2.8

56

0.01

0

Past

ures

with

isol

ated

tree

s x F

ores

t cov

er

0.23

5 0.

191

1.23

0 0.

234

Seco

ndar

y fo

rest

x F

ores

t cov

er

0.36

3 0.

173

2.10

4 0.

049

cont

inue

d

232

233

App

endi

x G

. (co

ntin

ued)

Sh

ade

coff

ee x

For

est c

over

0.

070

0.27

3 0.

256

0.80

1

Succ

essi

onal

x F

ores

t cov

er

0.52

6 0.

181

2.90

5 0.

009

Past

ures

with

isol

ated

tree

s x lo

cal s

truct

ure

12.6

41

2.93

3 4.

310

0.00

0

Seco

ndar

y fo

rest

x lo

cal s

truct

ure

-0.7

04

4.24

6 -0

.166

0.

870

Shad

e co

ffee

x lo

cal s

truct

ure

60.2

30

28.9

72

2.07

9 0.

051

Succ

essi

onal

x lo

cal s

truct

ure

7.33

0 2.

574

2.84

8 0.

010

Loca

l stru

ctur

e x

fore

st c

over

0.

094

0.04

1 2.

298

0.03

3

Past

ures

with

isol

ated

tree

s x F

ores

t cov

er x

loca

l stru

ctur

e -0

.175

0.

080

-2.1

85

0.04

2

Seco

ndar

y fo

rest

x F

ores

t cov

er x

loca

l stru

ctur

e 0.

121

0.10

1 1.

192

0.24

8

Shad

e co

ffee

x F

ores

t cov

er x

loca

l stru

ctur

e -1

.095

0.

508

-2.1

56

0.04

4

Succ

essi

onal

x F

ores

t cov

er x

loca

l stru

ctur

e -0

.121

0.

046

-2.6

54

0.01

6

Floc

k ab

unda

nce

= ha

bita

t typ

e +

loca

l str

uctu

re +

fore

st c

over

+ in

tera

ctio

ns

Inte

rcep

t 8.

459

3.09

3 2.

735

0.01

3

cont

inue

d

233

234

App

endi

x G

. (co

ntin

ued)

H

abita

t (Pa

stur

es w

ith is

olat

ed tr

ees)

-4

.679

3.

296

-1.4

2 0.

172

Hab

itat (

Seco

ndar

y fo

rest

) -6

.070

3.

171

-1.9

15

0.07

1

Hab

itat (

Shad

e co

ffee

) -4

.861

5.

254

-0.9

25

0.36

6

Hab

itat (

Succ

essi

onal

) -8

.231

3.

257

-2.5

27

0.02

1

Fore

st c

over

-0

.088

0.

053

-1.6

52

0.11

5

Loca

l stru

ctur

e -1

.325

0.

745

-1.7

78

0.09

1

Past

ures

with

isol

ated

tree

s x F

ores

t cov

er

0.06

7 0.

062

1.08

4 0.

292

Seco

ndar

y fo

rest

x F

ores

t cov

er

0.09

2 0.

055

1.66

1 0.

113

Shad

e co

ffee

x F

ores

t cov

er

0.07

2 0.

088

0.81

6 0.

425

Succ

essi

onal

x F

ores

t cov

er

0.13

0 0.

058

2.22

5 0.

038

Past

ures

with

isol

ated

tree

s x lo

cal s

truct

ure

3.34

6 0.

943

3.55

0.

002

Seco

ndar

y fo

rest

x lo

cal s

truct

ure

0.96

2 1.

365

0.70

5 0.

489

Shad

e co

ffee

x lo

cal s

truct

ure

3.23

5 9.

312

0.34

7 0.

732

cont

inue

d

234

235

App

endi

x G

. (co

ntin

ued)

Su

cces

sion

al x

loca

l stru

ctur

e 2.

025

0.82

7 2.

448

0.02

4

Loca

l stru

ctur

e x

fore

st c

over

0.

020

0.01

3 1.

531

0.14

2

Past

ures

with

isol

ated

tree

s x F

ores

t cov

er x

loca

l stru

ctur

e -0

.066

0.

026

-2.5

79

0.01

8

Seco

ndar

y fo

rest

x F

ores

t cov

er x

loca

l stru

ctur

e -0

.009

0.

033

-0.2

8 0.

782

Shad

e co

ffee

x F

ores

t cov

er x

loca

l stru

ctur

e -0

.068

0.

163

-0.4

16

0.68

2

Succ

essi

onal

x F

ores

t cov

er x

loca

l stru

ctur

e -0

.034

0.

015

-2.3

17

0.03

2

Floc

k ab

unda

nce

= ha

bita

t typ

e +

loca

l str

uctu

re +

hab

itat t

ype

x lo

cal

stru

ctur

e

Inte

rcep

t 3.

4 0.

534

6.36

3 0.

001

Hab

itat (

Past

ures

with

isol

ated

tree

s)

-0.8

42

0.64

8 -1

.299

0.

204

Hab

itat (

Seco

ndar

y fo

rest

) -0

.764

0.

591

-1.2

93

0.20

6

Hab

itat (

Shad

e co

ffee

) -0

.762

0.

755

-1.0

10

0.32

1

Hab

itat (

Succ

essi

onal

) -1

.977

0.

617

-3.2

05

0.00

3

Con

tinue

d

235

236

App

endi

x G

. (co

ntin

ued)

Lo

cal s

truct

ure

-0.1

91

0.16

0 -1

.194

0.

242

Past

ures

with

isol

ated

tree

s x lo

cal s

truct

ure

1.05

6 0.

324

3.25

8 0.

003

Seco

ndar

y fo

rest

x lo

cal s

truct

ure

0.30

0 0.

342

0.87

7 0.

388

Shad

e co

ffee

x lo

cal s

truct

ure

-0.5

23

1.15

5 -0

.453

0.

654

Succ

essi

onal

x lo

cal s

truct

ure

0.87

6 0.

223

3.92

7 0.

001

Floc

k en

coun

ter

rate

= h

abita

t typ

e +

fore

st c

over

+ h

abita

t typ

e x

fore

st

cove

r

Inte

rcep

t 0.

916

0.34

8 -0

.955

0.

348

Hab

itat (

Past

ures

with

isol

ated

tree

s)

0.98

2 0.

394

-0.0

36

0.97

2

Hab

itat (

Seco

ndar

y fo

rest

) 1.

017

0.41

7 -0

.079

0.

938

Hab

itat (

Shad

e co

ffee

) 1.

226

0.54

6 -1

.812

0.

080

Hab

itat (

Succ

essi

onal

) 0.

964

0.38

1 -1

.026

0.

314

Fore

st c

over

0.

506

0.00

6 -0

.284

0.

778

Past

ures

with

isol

ated

tree

s x F

ores

t cov

er

0.50

8 0.

008

0.12

0 0.

906

Seco

ndar

y fo

rest

x F

ores

t cov

er

0.50

8 0.

008

0.84

3 0.

406

cont

inue

d

236

237

App

endi

x G

. (co

ntin

ued)

Sh

ade

coff

ee x

For

est c

over

0.

510

0.01

0 2.

843

0.00

8

Succ

essi

onal

x F

ores

t cov

er

0.50

7 0.

007

1.32

2 0.

197

Floc

k en

coun

ter

rate

= lo

cal s

truc

ture

+ fo

rest

cov

er +

fore

st c

over

x lo

cal

stru

ctur

e

Inte

rcep

t 0.

629

0.12

2 -4

.625

0.

000

Loca

l stru

ctur

e 0.

558

0.05

7 1.

559

0.12

8

Fore

st c

over

0.

503

0.00

3 3.

136

0.00

3

Loca

l stru

ctur

e x

fore

st c

over

0.

501

0.00

1 -2

.725

0.

010

237

238

App

endi

x H

. Coe

ffic

ient

s of t

op-r

anke

d re

gres

sion

mod

els (

ΔAIC

c <

2) re

latin

g N

eotro

pica

l mig

rant

attr

ibut

es a

nd e

nviro

nmen

tal

varia

bles

in th

e A

ndes

. Sta

tistic

s inc

lude

mod

el e

stim

ates

, the

stan

dard

err

ors (

SE),

t for

est

imat

e an

d P

valu

e.

Para

met

ers

Estim

ate

SE

t P

NT

MB

ric

hnes

s = lo

cal s

truc

ture

+ fo

rest

cov

er +

loca

l str

uctu

re x

fore

st c

over

In

terc

ept

-0.0

39

0.10

8 -0

.362

0.

718

Loca

l stru

ctur

e 0.

150

0.06

3 2.

389

0.01

9

Fore

st c

over

0.

001

0.00

2 0.

426

0.67

1

Loca

l stru

ctur

e x

fore

st c

over

-0

.005

0.

001

-4.0

26

0.00

0

NTM

B ri

chne

ss =

Hab

itat

Inte

rcep

t -0

.401

0.

095

-4.2

33

0.00

0

Hab

itat x

Pas

ture

s with

isol

ated

tree

s 0.

428

0.14

1 3.

040

0.00

3

Hab

itat x

Sec

onda

ry fo

rest

0.

384

0.12

0 3.

201

0.00

2

Hab

itat x

Sha

de c

offe

e 0.

656

0.16

4 3.

997

0.00

0

Hab

itat x

Suc

cess

iona

l 0.

071

0.15

0 0.

477

0.63

5

NT

MB

abu

ndan

ce =

loca

l str

uctu

re +

fore

st c

over

+ lo

cal s

truc

ture

x fo

rest

cov

er

Inte

rcep

t 0.

455

0.21

6 2.

112

0.03

8

Loca

l stru

ctur

e 0.

264

0.12

6 2.

101

0.03

9

Fore

st c

over

0.

004

0.00

5 0.

880

0.38

1

Loca

l stru

ctur

e x

fore

st c

over

-0

.009

0.

002

-3.9

52

0.00

1

co

ntin

ued

238

239

App

endi

x H

. (co

ntin

ued)

N

TM

B a

bund

ance

= H

abita

t

Inte

rcep

t -0

.205

0.

189

-1.0

83

0.28

2

Hab

itat (

Past

ures

with

isol

ated

tree

s)

0.96

3 0.

280

3.43

8 0.

001

Hab

itat (

Seco

ndar

y fo

rest

) 0.

685

0.23

9 2.

866

0.00

5

Hab

itat (

Shad

e co

ffee

) 1.

456

0.32

7 4.

451

0.00

1

Hab

itat (

Succ

essi

onal

) 0.

288

0.29

9 0.

965

0.33

8

239

240

App

endi

x I.

Occ

urre

nce

of N

eotro

pica

l-Nea

rctic

mig

rant

land

bird

s in

84 1

-km

2 pix

els s

urve

yed

in 1

1 di

ffer

ent r

egio

ns in

the

And

es

in C

olom

bia,

Ecu

ador

and

Per

u. W

inte

ring

seas

ons 2

007-

2010

.

LOC

ALI

TY

ID C

OD

E SW

TH

GC

TH

CER

W

BLB

W

BB

WA

G

CFL

B

AW

W

AM

RE

SUTA

TE

WA

Em

pido

nax

Flyc

atch

ers

RB

GR

N

OW

A

REV

I

Agu

achi

ca

Ran

dom

Cen

ter (

124)

X

X

X

Agu

achi

ca

Ran

dom

Eas

t (12

4)

X

X

X

X

Agu

achi

ca

Ran

dom

Nor

th (1

24)

X

X

X

X

X

A

guac

hica

R

ando

m S

outh

(124

) X

X

X

X

Agu

achi

ca

Ran

dom

Wes

t (12

4)

X

X

X

X

Agu

achi

ca

Paire

d C

ente

r (12

4)

X

X

X

X

X

X

X

X

X

Agu

achi

ca

Paire

d Ea

st (1

24)

X

X

X

X

Agu

achi

ca

Paire

d N

orth

(124

)

X

Agu

achi

ca

Paire

d So

uth

(124

) X

X

X

Agu

achi

ca

Paire

d W

est (

124)

X

X

X

X

X

X

X

Sn J.

de

la M

onta

ña

Ran

dom

Eas

t (21

6)

X

X

X

X

X

X

X

Sn

J. d

e la

Mon

taña

R

ando

m N

orth

(216

)

X

X

co

ntin

ued

240

241

App

endi

x I.

(con

tinue

d)

Sn J.

de

la M

onta

ña

Paire

d W

est (

216)

X

X

X

San

V. d

e C

hucu

rí R

ando

m C

ente

r (23

1)

X

X

X

Sa

n V

. de

Chu

curí

Ran

dom

Eas

t (23

1)

X

X

X

X

San

V. d

e C

hucu

rí R

ando

m N

orth

(231

)

X

X

X

San

V. d

e C

hucu

rí R

ando

m W

est (

231)

X

X

X

X

X

San

V. d

e C

hucu

rí Pa

ired

Cen

ter (

231)

X

X

X

San

V. d

e C

hucu

rí Pa

ired

East

(231

) X

X

X

X

Sa

n V

. de

Chu

curí

Paire

d N

orth

(231

)

X

X

X

San

V. d

e C

hucu

rí Pa

ired

Sout

h (2

31)

X

X

X

San

V. d

e C

hucu

rí Pa

ired

Wes

t (23

1)

X

X

X

X

X

R

icau

te, S

anta

nder

R

ando

m C

ente

r (24

8)

X

R

icau

te, S

anta

nder

R

ando

m E

ast (

248)

R

icau

te, S

anta

nder

R

ando

m N

orth

(248

)

R

icau

te, S

anta

nder

R

ando

m S

outh

(248

)

R

icau

te, S

anta

nder

R

ando

m W

est (

248)

R

icau

te, S

anta

nder

Pa

ired

Cen

ter (

248)

R

icau

te, S

anta

nder

Pa

ired

East

(248

)

X

co

ntin

ued

241

242

App

endi

x I.

(con

tinue

d)

Ric

aute

, San

tand

er

Paire

d N

orth

(248

)

R

icau

te, S

anta

nder

Pa

ired

Sout

h (2

48)

Abe

jorr

al

Paire

d C

ente

r (30

7)

X

X

X

X

X

X

X

Abe

jorr

al

Paire

d Ea

st (3

07)

X

X

X

X

X

X

X

X

X

A

bejo

rral

Pa

ired

Nor

th (3

07)

X

X

X

X

X

X

Abe

jorr

al

Paire

d W

est (

307)

X

X

X

X

X

Paya

, Boy

acá

Ran

dom

Cen

ter (

314)

X

Paya

, Boy

acá

Ran

dom

Eas

t (31

4)

X

X

X

X

X

Pa

ya, B

oyac

á R

ando

m N

orth

(314

) X

X

X

X

X

X

Pa

ya, B

oyac

á R

ando

m S

outh

(314

)

X

Paya

, Boy

acá

Ran

dom

Wes

t (31

4)

Paya

, Boy

acá

Paire

d C

ente

r (31

4)

X

Pa

ya, B

oyac

á Pa

ired

East

(314

)

X

X

Pa

ya, B

oyac

á Pa

ired

Nor

th (3

14)

X

X

Paya

, Boy

acá

Paire

d So

uth

(314

)

X

X

X

Paya

, Boy

acá

Paire

d W

est (

314)

Ib

agué

R

ando

m C

ente

r (39

5)

X

cont

inue

d

242

243

App

endi

x I.

(con

tinue

d)

Ibag

ué

Ran

dom

Eas

t (39

5)

X

Ib

agué

R

ando

m N

orth

(395

)

X

X

X

Ibag

ué

Ran

dom

Sou

th (3

95)

Ibag

ué

Ran

dom

Wes

t (39

5)

X

X

X

Ib

agué

Pa

ired

Cen

ter (

395)

X

X

X

Ibag

ué

Paire

d Ea

st (3

95)

X

X

Ibag

ué

Paire

d N

orth

(395

)

X

Ibag

ué

Paire

d So

uth

(395

)

X

X

Ib

agué

Pa

ired

Wes

t (39

5)

X

X

Ros

as, C

auca

R

ando

m C

ente

r (56

1)

X

X

X

R

osas

, Cau

ca

Ran

dom

Eas

t (56

1)

X

X

X

X

X

X

Ros

as, C

auca

R

ando

m N

orth

(561

)

X

X

R

osas

, Cau

ca

Ran

dom

Sou

th (5

61)

X

X

X

X

Ros

as, C

auca

R

ando

m W

est (

561)

X

X

X

X

X

Ros

as, C

auca

Pa

ired

Cen

ter (

561)

R

osas

, Cau

ca

Paire

d Ea

st (5

61)

X

X

X

Pa

tía, C

auca

R

ando

m C

ente

r (58

1)

X

X

cont

inue

d

243

244

App

endi

x I.

(con

tinue

d)

Patía

, Cau

ca

Ran

dom

Eas

t (58

1)

X

X

Patía

, Cau

ca

Ran

dom

Wes

t (58

1)

X

Patía

, Cau

ca

Ran

dom

Nor

th (5

81)

X

X

X

Patía

, Cau

ca

Ran

dom

Sou

th (5

81)

X

X

Patía

, Cau

ca

Paire

d C

ente

r (58

1)

X

X

Patía

, Cau

ca

Paire

d Ea

st (5

81)

X

Patía

, Cau

ca

Paire

d N

orth

(581

)

X

Patía

, Cau

ca

Paire

d So

uth

(581

)

X

Patía

, Cau

ca

Paire

d W

est (

581)

X

X

X

X

X

P.N

San

gay

Ran

dom

Cen

ter (

667)

X

P.N

San

gay

Ran

dom

Eas

t (66

7)

P.N

San

gay

Ran

dom

Nor

th (6

67)

P.N

San

gay

Ran

dom

Sou

th (6

67)

P.N

San

gay

Paire

d C

ente

r (66

7)

P.N

San

gay

Paire

d Ea

st (6

67)

P.N

San

gay

Paire

d N

orth

(667

)

X

cont

inue

d

244

245

App

endi

x I.

(con

tinue

d)

P.N

San

gay

Paire

d So

uth

(667

)

X

P.N

San

gay

Paire

d W

est (

667)

C

hing

ozal

es

Ran

dom

Nor

th (7

34)

Chi

ngoz

ales

R

ando

m S

outh

(734

)

C

hing

ozal

es

Ran

dom

Wes

t (73

4)

X

245

246

App

endi

x J.

Rel

atio

nshi

p of

bod

y co

nditi

on a

nd se

x, a

ge, b

ody

mol

t and

seas

on fo

r Neo

tropi

cal-N

earc

tic m

igra

tory

bird

spec

ies i

n

shad

ed m

onoc

ultu

res i

n So

uthw

este

rn A

ntio

quia

dep

artm

ent,

Col

ombi

a, 2

008-

2010

. *P

< 0.

05 a

nd *

*P <

0.0

1.

Spec

ies

Sex

Age

B

ody

mol

t Y

EAR

Cer

ulea

n W

arbl

er

F 1,5

2= 0

.28

F 1,5

2= 0

.02

F 1,5

2= 1

.08

F 1,5

2= 0

.0

Bla

ckbu

rnia

n W

arbl

er

F 1,1

22=

0.83

F 1

,122

= 0.

48

F 1,1

22=

2.58

F 1

,122

= 0.

24

Tenn

esse

e W

arbl

er

F 1,1

44=

3.18

F 1

,172

= 0.

65

F 1,1

72=

0.49

F 1

,172

= 0.

49

Can

ada

War

bler

F 1

,60=

0.3

1 F 1

,70=

0.0

4 F 1

,71=

2.5

7 F 1

,71=

2.3

3

Ros

e-br

east

ed G

rosb

eak

F 1,8

0= 2

.14

F 1,8

0= 0

.46

F 1,8

0= 0

.04

F 1,8

0= 0

.11

Red

-eye

d V

ireo

- F 1

,26=

2.8

2 F 1

,26=

0.0

2 F 1

,26=

0.0

2

Sum

mer

Tan

ager

F 1

,51=

3.3

6 F 1

,55=

0.2

8 F 1

,55=

0.3

9 F 1

,55=

2.9

8

Empi

dona

x fly

catc

hers

-

F 1,3

9= 0

.27

F 1,3

9= 0

.78

F 1,3

9= 0

.09

246

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ECOLOGY AND CONSERVATION OF NEOTROPICAL-NEARCTIC MIGRATORY DISSERTATION Presented in Partial...

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