Bird Conservation: Global evidence for the effects of interventions. Contents and sample chapter

7/29/2019 Bird Conservation: Global evidence for the effects of interventions. Contents and sample chapter

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Published by Pelagic Publishingwww.pelagicpublishing.comPO Box 725, Exeter EX1 9QU

Bird Conservation

Global evidence for the effects of interventionsSynopses of Conservation Evidence, Volume 2

ISBN 978-1-907807-19-0 (Pbk)ISBN 978-1-907807-20-6 (Hbk)

Copyright 2013 William J. Sutherland

This book should be quoted as Williams, D. R., Pople, R. G., Showler, D. A., Dicks, L. V., Child,M. F., zu Ermgassen, E. K. H. J. and Sutherland, W. J. (2013) Bird Conservation: Global evidence forthe effects of interventions. Exeter, Pelagic Publishing.

All rights reserved. Apart from short excerpts for use in research or for reviews, no part of thisdocument may be printed or reproduced, stored in a retrieval system, or transmitted in any form or

by any means, electronic, mechanical, photocopying, recording, now known or hereafter invented orotherwise without prior permission from the publisher.

British Library Cataloguing in Publication DataA catalogue record for this book is available from the British Library.


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Contents

Advisory board xiv

About the authors xvAcknowledgements xvi

1. About this book 1

2. Habitat protection 7Key messages 72.1. Legally protect habitats 82.2. Ensure connectivity between habitat patches 92.3. Provide or retain un-harvested buffer strips 10

3. Education and awareness raising 13Key messages 133.1. Raise awareness amongst the general public through campaigns and

public information 133.2. Provide bird feeding materials to families with young children 143.3. Enhance bird taxonomy skills through higher education and training 143.4. Provide training to conservationists and land managers on bird ecology

and conservation 14

4. Threat: Residential and commercial development 15Key messages 154.1. Angle windows to reduce collisions 154.2. Mark or tint windows to reduce collision mortality 15

5. Threat: Agriculture 17Key messages All farming systems 17Key messages Arable farming 20Key messages Livestock farming 21Key messages Perennial, non-timber crops 23

Key messages Aquaculture 24

All farming systems 255.1. Support or maintain low-intensity agricultural systems 255.2. Practise integrated farm management 255.3. Food labelling schemes relating to biodiversity-friendly farming 255.4. Increase the proportion of natural/semi-natural vegetation in

the farmed landscape 255.5. Pay farmers to cover the costs of conservation measures 275.6. Cross compliance standards for all subsidy payments 365.7. Reduce eld size (or maintain small elds) 375.8. Provide or retain set-aside areas in farmland 375.9. Manage hedges to benet wildlife 425.10. Plant new hedges 445.11. Manage stone-faced hedge banks to benet birds 445.12. Manage ditches to benet wildlife 455.13. Protect in-eld trees 465.14. Plant in-eld trees 46


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5.15. Tree pollarding and tree surgery 465.16. Plant wild bird seed or cover mixture 465.17. Plant nectar ower mixture/wildower strips 555.18. Create uncultivated margins around intensive arable

or pasture elds 575.19. Plant grass buffer strips/margins around arable or pasture elds 59

5.20. Use mowing techniques to reduce chick mortality 635.21. Provide refuges in elds during harvest or mowing 645.22. Mark bird nests during harvest or mowing 645.23. Relocate nests at harvest time to reduce nestling mortality 655.24. Make direct payments per clutch for farmland birds 655.25. Control scrub on farmland 665.26. Take eld corners out of management 675.27. Reduce conict by deterring birds from taking crops 67

Arable farming 685.28. Increase crop diversity 68

5.29. Implement mosaic management 695.30. Leave overwinter stubbles 695.31. Plant nettle strips 735.32. Leave unharvested cereal headlands within arable elds 735.33. Plant crops in spring rather than autumn 735.34. Undersow spring cereals, with clover for example 755.35. Plant more than one crop per eld (intercropping) 765.36. Revert arable land to permanent grassland 765.37. Reduce tillage 785.38. Add 1% barley into wheat crop for corn buntings 81

5.39. Leave uncropped, cultivated margins or plots (includes lapwingand stone curlew plots) 81

5.40. Create skylark plots 835.41. Create corn bunting plots 845.42. Plant cereals in wide-spaced rows 855.43. Create beetle banks 85

Livestock farming 875.44. Maintain species-rich, semi-natural grassland 875.45. Reduce management intensity on permanent grasslands 885.46. Reduce grazing intensity 905.47. Provide short grass for waders 935.48. Raise mowing height on grasslands 935.49. Delay mowing date or rst grazing date on grasslands 945.50. Leave uncut rye grass in silage elds 955.51. Plant cereals for wholecrop silage 965.52. Maintain lowland heathland 975.53. Maintain rush pastures 975.54. Maintain traditional water meadows 985.55. Maintain upland heath/moor 995.56. Plant Brassica fodder crops 1005.57. Use mixed stocking 1005.58. Use traditional breeds of livestock 1005.59. Maintain wood pasture and parkland 1005.60. Exclude grazers from semi-natural habitats (including woodland) 1005.61. Protect nests from livestock to reduce trampling 1035.62. Mark fences to reduce bird collision mortality 1035.63. Create open patches or strips in permanent grassland 104


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Perennial, non-timber crops 1045.64. Maintain traditional orchards 1055.65. Manage perennial bioenergy crops to benet wildlife 105

Aquaculture 1065.66. Reduce conict with humans to reduce persecution 1065.67. Scare birds from sh farms 106

5.68. Disturb birds at roosts 1095.69. Use electric fencing to exclude sh-eating birds 1105.70. Use netting to exclude sh-eating birds 1115.71. Disturb birds using foot patrols 1125.72. Use mussel socks to prevent birds from attacking shellsh 1125.73. Translocate birds away from sh farms 1135.74. Increase water turbidity to reduce sh predation by birds 1135.75. Provide refuges for sh within ponds 1145.76. Use in-water devices to reduce sh loss from ponds 1145.77. Spray water to deter birds from ponds 115

5.78. Deter birds from landing on shellsh culture gear 115

6. Threat: Energy production and mining 117Key messages 1176.1. Paint wind turbines to increase their visibility 117

7. Threat: Transportation and service corridors 118Key messages Verges and airports 118Key messages Power lines and electricity pylons 118

Verges and airports 1197.1. Mow roadside verges 1197.2. Sow roadside verges 1197.3. Scare or otherwise deter birds from airports 119

Power lines and electricity pylons 1207.4. Bury or isolate power lines to reduce incidental mortality 1207.5. Remove earth wires to reduce incidental mortality 1217.6. Thicken earth wire to reduce incidental mortality 1217.7. Mark power lines to reduce incidental mortality 1217.8. Use raptor models to deter birds and so reduce incidental mortality 124

7.9. Add perches to electricity pylons to reduce electrocution 1247.10. Insulate power pylons to prevent electrocution 1257.11. Use perch-deterrents to stop raptors perching on pylons 1257.12. Reduce electrocutions by using plastic, not aluminium, leg rings

to mark birds 126

8. Threat: Biological resource use 127Key messages reducing exploitation and conict 127Key messages reducing sheries bycatch 128

Reducing exploitation and conict 1308.1. Use legislative regulation to protect wild populations 1308.2. Increase on-the-ground protection to reduce unsustainable levels

of exploitation 1328.3. Promote sustainable alternative livelihoods 1338.4. Use education programmes and local engagement to help reduce

persecution or exploitation of species 1338.5. Employ local people as biomonitors 135


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8.6. Mark eggs to reduce their appeal to egg collectors 1368.7. Relocate nestlings to reduce poaching 1368.8. Use wildlife refuges to reduce hunting disturbance 1378.9. Introduce voluntary maximum shoot distances 1388.10. Provide sacricial grasslands to reduce the impact of wild geese on crops 1388.11. Move sh-eating birds to reduce conict with shermen 139

8.12. Scare sh-eating birds from areas to reduce conict 139Reduce sheries bycatch 1398.13. Set longlines at night to reduce seabird bycatch 1408.14. Turn deck lights off during night-time setting of longlines to

reduce bycatch 1428.15. Use streamer lines to reduce seabird bycatch on longlines 1438.16. Use larger hooks to reduce seabird bycatch 1468.17. Use a water cannon when setting longlines to reduce seabird bycatch 1478.18. Set lines underwater to reduce seabird bycatch 1478.19. Set longlines at the side of the boat to reduce seabird bycatch 148

8.20. Use a line shooter to reduce seabird bycatch 1488.21. Use bait throwers to reduce seabird bycatch 1498.22. Tow buoys behind longlining boats to reduce seabird bycatch 1498.23. Dye baits to reduce seabird bycatch 1498.24. Use high-visibility longlines to reduce seabird bycatch 1508.25. Use a sonic scarer when setting longlines to reduce seabird bycatch 1508.26. Weight baits or lines to reduce longline bycatch of seabirds 1508.27. Use shark liver oil to deter birds when setting lines 1528.28. Thaw bait before setting lines to reduce seabird bycatch 1528.29. Reduce seabird bycatch by releasing offal overboard when setting

longlines 1538.30. Use bird exclusion devices such as Brickle curtains to reduce

seabird mortality when hauling longlines 1538.31. Use acoustic alerts on gillnets to reduce seabird bycatch 1548.32. Use high-visibility mesh on gillnets to reduce seabird bycatch 1548.33. Reduce gillnet deployment time to reduce seabird bycatch 1558.34. Mark trawler warp cables to reduce seabird collisions 1558.35. Reduce ghost shing by lost/discarded gear 1558.36. Reduce bycatch through seasonal or area closures 156

9. Threat: Human intrusions and disturbance 157Key messages 1579.1. Use wildlife refuges to reduce hunting disturbance 1579.2. Use signs and access restrictions to reduce disturbance at nest sites 1579.3. Set minimum distances for approaching birds (buffer zones) 1609.4. Provide paths to limit the extent of disturbance 1609.5. Reduce visitor group sizes 1619.6. Use voluntary agreements with local people to reduce disturbance 1619.7. Start educational programmes for personal watercraft owners 1619.8. Habituate birds to human visitors 1629.9. Use nest covers to reduce the impact of research on predation

of ground-nesting seabirds 162

10. Threat: Natural system modications 164Key messages 16410.1. Use prescribed burning 16710.2. Use re suppression/control 183


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10.3. Protect nest trees before burning 18410.4. Clear or open patches in forests 18410.5. Clearcut and re-seed forests 18610.6. Thin trees within forests 18710.7. Coppice trees 18910.8. Use patch retention harvesting instead of clearcutting 190

10.9. Use selective harvesting/logging instead of clearcutting 19110.10. Use variable retention management during forestry operations 19210.11. Use shelterwood cutting instead of clearcutting 19310.12. Manage woodland edges for birds 19310.13. Manually control or remove mid-storey and ground-level vegetation

(including mowing, chaining, cutting etc) 19410.14. Replace non-native species of tree/shrub 20210.15. Provide deadwood/snags in forests 20210.16. Remove coarse woody debris from forests 20410.17. Apply herbicide to mid- and under-storey vegetation 205

10.18. Treat wetlands with herbicide 20610.19. Employ grazing in natural and semi-natural habitats 20810.20. Plant trees to act as windbreaks 21410.21. Re-seed grasslands 21510.22. Fertilise articial grasslands 21510.23. Raise water levels in ditches or grassland 21710.24. Manage water level in wetlands 21810.25. Use environmentally sensitive ood management 22010.26. Use greentree reservoir management 22010.27. Plough habitats 221

10.28. Create scrapes and pools in wetlands and wet grasslands 222

11. Habitat restoration and creation 224Key messages 22411.1. Restore or create forests 22511.2. Restore or create grasslands 22911.3. Restore or create traditional water meadows 23511.4. Restore or create shrubland 23611.5. Restore or create savannas 23711.6. Restore or create wetlands and marine habitats 237

12. Threat: Invasive alien and other problematic species 243Key messages reduce predation by other species 243Key messages reduce incidental mortality during predator eradicationor control 244Key messages reduce nest predation by excluding predators from nestsor nesting areas 244Key messages reduce mortality by reducing hunting ability or changingpredator behaviour 245Key messages reduce competition with other species for food

and nest sites 246Key messages reduce adverse habitat alteration by other species 246Key messages reduce parasitism and disease 247Key messages reduce detrimental impacts of other problematic species 247

Reduce predation by other species 24812.1. Remove or control predators to enhance bird populations and

communities 248


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Predator control on islands 24912.2. Control avian predators on islands 24912.3. Control mammalian predators on islands 25112.4. Control invasive ants on islands 26112.5. Control predators not on islands 26112.6. Reduce predation by translocating predators 269

Reduce incidental mortality during predator eradication or control 27012.7. Do birds take bait designed for pest control? 27012.8. Distribute poison bait using dispensers 27112.9. Use repellents on baits 27112.10. Use coloured baits to reduce accidental mortality during predator

control 272

Reduce nest predation by excluding predators from nests or nesting areas 27312.11. Physically protect nests from predators using non-electric fencing 27312.12. Protect bird nests using electric fencing 274

12.13. Physically protect nests with individual exclosures/barriers orprovide shelters for chicks 27612.14. Can nest protection increase nest abandonment? 28112.15. Can nest protection increase predation of adults and chicks? 28212.16. Use articial nests that discourage predation 28312.17. Use multiple barriers to protect nests 28412.18. Plant nesting cover to reduce nest predation 28512.19. Use snakeskin to deter mammalian nest predators 28512.20. Use mirrors to deter nest predators 28512.21. Use naphthalene to deter mammalian predators 286

12.22. Use ultrasonic devices to deter cats 28612.23. Protect nests from ants 28612.24. Guard nests to prevent predation 28712.25. Use cat curfews to reduce predation 28712.26. Use lion dung to deter domestic cats 28712.27. Play spoken-word radio programmes to deter predators 287

Reduce mortality by reducing hunting ability or changing predatorbehaviour 28812.28. Use collar-mounted devices to reduce predation 28812.29. Use supplementary feeding to reduce predation 288

12.30. Use aversive conditioning to reduce nest predation 28912.31. Reduce predation by translocating nest boxes 293

Reduce competition with other species for food and nest sites 29412.32. Reduce inter-specic competition for nest sites by removing

competitor species 29412.33. Reduce inter-specic competition for nest sites by modifying habitats

to exclude competitor species 29812.34. Protect nest sties from competitors 29812.35. Reduce competition between species by providing nest boxes 29912.36. Reduce inter-specic competition for food by removing or controlling

competitor species 300

Reduce adverse habitat alteration by other species 30112.37. Reduce adverse habitat alterations by excluding problematic species 30112.38. Control or remove habitat-altering mammals 30312.39. Remove problematic vegetation 30412.40. Use buffer zones to reduce the impact of invasive plant control 305


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Reduce parasitism and disease 30612.41. Remove/treat endoparasites and diseases 30612.42. Exclude or control reservoir species to reduce parasite burdens 30712.43. Remove/treat ectoparasites to increase survival or reproductive success 30812.44. Guard nests to reduce risk of ectoparasites 31212.45. Remove/control brood parasites 312

12.46. Use false brood parasite eggs to discourage brood parasitism 31612.47. Provide supplementary food to increase parental presence andso reduce brood parasitism 316

12.48. Alter articial nest sites to discourage brood parasitism 317

Reduce detrimental impacts of other problematic species 31712.49. Use copper strips to exclude snails from nests 317

13. Threat: Pollution 318Key messages Industrial pollution 318Key messages Agricultural pollution 318Key message Air-borne pollutants 319Key messages Excess energy 319

Industrial pollution 32013.1. Clean birds following oil spills 32013.2. Relocate birds following oil spills 32213.3. Deter or prevent birds from landing on toxic pools 32313.4. Use repellents to deter birds from landing on pools polluted by mining 325

Agricultural pollution 325

13.5. Reduce pesticide or herbicide use generally 32513.6. Restrict certain pesticides or other agricultural chemicals 32713.7. Provide food for vultures to reduce mortality from diclofenac 32813.8. Make selective use of spring herbicides 32913.9. Use organic rather than mineral fertilisers 32913.10. Reduce chemical inputs in permanent grassland management 32913.11. Leave headlands in elds unsprayed (conservation headlands) 33013.12. Provide unfertilised cereal headlands in arable elds 33213.13. Plant riparian buffer strips 33213.14. Provide buffer strips around in-eld ponds 333

Air-borne pollutants 33313.15. Use lime to reduce acidication in lakes 333

Excess energy 33313.16. Reduce incidental mortality from birds being attracted to

articial lights 33313.17. Turn off lights to reduce mortality from articial lights 33413.18. Reduce the intensity of lighthouse beams 33413.19. Shield lights to reduce mortality from articial lights 33413.20. Use ashing lights to reduce mortality from articial lights 335

13.21. Use lights low in spectral red to reduce mortality from articial lights 33513.22. Use volunteers to collect downed birds and rehabilitate them 336

14. Threat: Climate change, extreme weather and geological events 337Key messages 33714.1. Water nesting mounds to increase incubation success in malleefowl 33714.2. Replace nesting substrate following severe weather 338


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15. General responses to small/declining populations 339Key messages inducing breeding, rehabituation and egg removal 339Key messages provide articial nesting sites 339Key messages foster chicks in the wild 340Key messages provide supplementary food 341Key messages translocations 342

15.1. Use articial visual and auditory stimuli to induce breeding inwild populations 343

15.2. Rehabilitate injured birds 34315.3. Remove eggs from wild nests to increase reproductive output 34415.4. Provide articial nesting sites 34515.5. Clean nest boxes to increase occupancy or reproductive success 39015.6. Use differently-coloured articial nests 39215.7. Provide nesting material for wild birds 39315.8. Repair/support nests to support breeding 39315.9. Articially incubate eggs or warm nests 394

15.10. Provide nesting habitat for birds that is safe from extreme weather 39415.11. Remove vegetation to create nesting areas 39515.12. Guard nests to increase nest success 397

Foster chicks in the wild 39815.13. Foster eggs or chicks with wild conspecics 39815.14. Foster eggs or chicks with wild non-conspecics (cross-fostering) 404

Provide supplementary food 40715.15. Provide supplementary food to increase reproductive success 40815.16. Provide supplementary food to allow the rescue of a second chick 43015.17. Provide supplementary food to increase adult survival 43115.18. Can supplementary feeding increase predation or parasitism? 44915.19. Provide supplementary food through the establishment of food

populations 45015.20. Use perches to increase foraging success 45115.21. Place feeders close to windows to reduce collisions 45215.22. Provide supplementary water to increase survival or reproductive

success 45315.23. Provide calcium supplements to increase survival or reproductive

success 453

Translocations 45715.24. Translocate birds to re-establish populations or increase genetic

variation 45715.25. Use techniques to increase the survival of species after capture 47415.26. Ensure translocated birds are familiar with each other

before release 47515.27. Ensure genetic variation to increase translocation success 47515.28. Translocate nests to avoid disturbance 47615.29. Use vocalisations to attract birds to new sites 477

15.30. Use decoys to attract birds to new sites 47915.31. Alter habitat to encourage birds to leave an area 481

16. Captive breeding, rearing and releases (ex situconservation) 483Key messages captive breeding 483Key messages release of captive-bred individuals 484


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Captive breeding 48516.1. Use captive breeding to increase or maintain populations 48516.2. Can captive breeding have deleterious effects on individual tness? 49016.3. Use articial insemination in captive breeding 49116.4. Freeze semen for use in articial insemination 49216.5. Wash contaminated semen and use it for articial insemination 493

16.6. Articially incubate and hand-rear birds in captivity 49416.7. Use puppets to increase the success of hand-rearing 504

Release of captive-bred individuals 50516.8. Release captive-bred individuals into the wild to restore or augment

wild populations 50516.9. Use appropriate populations to source released populations 52016.10. Use holding pens at release sites 52116.11. Clip birds wings on release 52316.12. Release birds in groups 52416.13. Release chicks and adults in coveys 524

16.14. Release birds as adults or sub-adults, not juveniles 52516.15. Use anti-predator training to improve survival after release 52716.16. Use ying training before release 52816.17. Provide supplementary food during and after release 52916.18. Use microlites to help birds migrate 530

Index 531


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9. Threat: Human intrusions and disturbance

Key messages

Use signs and access restrictions to reduce disturbance at nest sitesSix studies from across the world found increased numbers of breeders, higher reproductivesuccess or lower levels of disturbance in waders and terns following the start of access restric-tions or the erection of signs near nesting areas. Two studies from Europe and Antarctica foundno effect of access restrictions on reproductive success in eagles and penguins, respectively.

Set minimum distances for approaching birds (buffer zones)We captured no intervention-based evidence for the effects on bird populations of settingminimum distances for approaching birds.

Provide paths to limit disturbanceA study from the UK found that two waders nested closer to a path, or at higher densities nearthe path, following resurfacing, which resulted in far fewer people leaving the path.

Reduce visitor group sizesWe found no intervention-based evidence for the effects of limiting visitor group sizes on birdpopulations.

Use voluntary agreements with local people to reduce disturbanceA before-and-after trial in the USA found signicantly lower rates of waterfowl disturbancefollowing the establishment of a voluntary waterfowl avoidance area, despite an overall increase

in boat trafc.

Start educational programmes for personal watercraft ownersA before-and-after study in the USA found that common tern reproduction increased, and ratesof disturbance decreased, following a series of educational programmes aimed at recreational

boat users.

Habituate birds to visitorsA study from Australia found that bridled terns from heavily disturbed sites had similar orhigher reproductive success compared with less-disturbed sites, possibly suggesting that habit-uation had occurred.

Use nest covers to reduce the impact of research on predation of ground-nestingseabirds

A before-and-after study from Canada found that hatching success of Caspian terns was sig-nicantly higher when researchers protected nests after disturbing adults from them.

9.1. Use wildlife refuges to reduce hunting disturbance

BackgroundWildlife refuges are areas where hunting is prohibited. They reduce mortality from hunt-

ing and the disturbance it causes. Studies describing the effects of refuges are discussedin Threat: Biological resource use.

9.2. Use signs and access restrictions to reduce disturbanceat nest sites

Six studies (two replicated and controlled, two before-and-after and two small studies) fromacross the world (2,3,5,710) found increased numbers of breeders (2,8), higher reproductive


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158 Threat: Human intrusions and disturbance

success (3,5,9,10) or lower levels of disturbance (5,7) in waders and terns following the start of

access restrictions or the erection of signs near nesting areas. One Canadian study (2) involved

the use of multiple interventions.

A before-and-after study from the USA (6) found that a colony of black-crowned night heronsNycticorax nycticoraxwas successfully relocated to an area with no public access.

One small study from Europe (1) and one replicated and controlled study from Antarctica (4)found no effect of access restrictions on the reproductive success of eagles or penguins,

respectively.

BackgroundIf most disturbance to nesting birds is accidental, then simply warning the public thatthere are birds present, or restricting access at certain times of the year may help reducedisturbance and the abandonment or destruction of nests. Conversely, if disturbance iscoming from people attempting to see nests or birds, then alerting the public to their pre-sence with signs could be counter-productive.

A small study in 1976 88 in the wetlands of the Doana National Park, Andalucia, Spain (1),found that there were no differences in number of Spanish imperial eagle Aquila adalbertipairs that laid, clutch size, hatching size or nestling survival after trails near nests weretemporarily closed. This study discusses other eagle management techniques, described inAdd perches to electricity pylons to reduce electrocution, Bury or isolate power lines,Foster eggs or chicks with wild conspecics and Remove/treat endoparasites.

Two before-and-after studies in 1977 89 at two common tern Sterna hirundo colonies inLake Ontario, Canada (2), found that the nesting population increased at one colony but

decreased at the second following the use of several interventions, including the erection ofsigns highlighting the presence of nesting birds. This study is discussed in Replace nestingsubstrate following severe weather.

A replicated controlled study on a 28 km stretch of coast in a heavily-visited national parkin Victoria, Australia (3), found that hooded plovers Thinornis rubricollis had signicantlyhigher reproductive success in 1991 8 under three restricted-access regimes, compared to tworegimes that allowed dogs on the beach (0.55 edglings/clutch for 40 restricted access clutchesvs. 0.10 edglings/clutch for 131 open-access clutches). Hatching success was 31 40% andedging success 31 68% for the 40 clutches in areas with no access for dogs; both dogsand people or under a Plover Watch scheme, where volunteers ask people to avoid nests andcontrol dogs. This compared with hatching and edging success of 0 12% and 0 16% for 131clutches in areas where dogs were prohibited from 0900 1700 each day or where there wasunrestricted access to people and dogs. Overall, the average number of edglings increasedover the study period.

A replicated, controlled study on Goudier Island (2 ha), Antarctica (4), in the austral sum-mer of 1996 7, found that gentoo penguins Pygoscelis papuadid not have signicantly higherreproductive success at colonies with no access by tourists, compared to six colonies that tour-ists could walk through. The percentage of birds laying and eggs hatching did not vary

between colonies (82 98% of birds laying and 7195% of eggs hatching for 556 nests in dis-turbed colonies vs. 89 100% laying and 88 90% hatching for 170 nests in control colonies), nordid the growth rates of chicks. Overall, 3,103 tourists visited the island making a total of 7,938man-hours of visits over four months. Tourists could walk under supervision through sixdisturbed colonies but could not approach closer than 25 m to four protected colonies (withtwo 70 m away and partially concealed by rocks).

A before-and-after trial from JulyAugust in 19971998 in the waterways surrounding acommon tern Sterna hirundonesting island in Barnegat Bay, USA (5), found that disturbanceand reproductive costs caused by personal watercraft disturbance signicantly decreasedafter the implementation of educational campaigns and increased signage in late 1997. Thisstudy is discussed in Start educational programs for personal watercraft owners.


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Use signs and access restrictions to reduce disturbance at nest sites 159

A before-and-after trial at a coastal site in Long Beach, California, USA (6), reported thesuccessful translocation of a black-crowned night heron Nycticorax nycticorax colony to a sitewhere public access was stopped. This study is discussed in Translocate individuals.

A replicated before-and-after study in 1982, 1987, 1992 and 2002 at 17 local beaches withinDelaware Bay, USA (7) found that disturbance to shorebirds decreased markedly followingintensive management intervention to control birdwatchers and crab collectors. Both the

mean disruption rate and the mean time that shorebirds were disturbed increased during the1980s when there were no restrictions or viewing platforms and then declined by 2002 afterviewing platforms were constructed and beach access restrictions were enforced (5.6 disrup-tions/hour and 53 minutes disturbed/hour in 1987 vs. 0.4 and 3.6 in 2002). Fewer people wereobserved on the beaches after restrictions were enforced and only one bird watcher disturbedthe birds in 2002. However, the percentage of disturbed shorebirds that ew away (and didnot return within 10 min) did not change during the 1980s and increased in 2002. Observationswere made on 12 20 days each year for 6 10 h per day.

A small before-and-after study on a beach in California, USA (8), found that the numberof breeding snowy plovers Charadrius alexandrinusincreased from one pair in 2001 to 26 pairs

(edging 74 young) in 2004, following the installation of a simple rope fence in June 2001. Theprobability of eggs being trampled in 2002 was 8% outside the roped area, compared with 0%inside. The fence consisted of metal posts every 5 m and a single rope strung across the top.In 2001, 265 m of beach was roped off; this increased to 400 m in 2002 and further increasedin 2003 4.

A replicated, controlled study at three sandy beaches in Algarve, Portugal (9), found thatlittle tern Sterna albifronsbreeding success in 2003 5 was signicantly higher on two beacheswith information and warning signs and weekend wardening, compared to a beach withoutprotective measures (50 91% nesting success for 339 nests on the two protected beaches vs.0 35% success for 153 nests on the unprotected beach). The presence/absence of protective

measures was the most important predictor of nesting success. The main causes of nest failurewere predation, destruction by humans and dogs and abandonment.A small study in Victoria, Australia, between 2003 and 2007 (10) found that two hooded

plover Thinornis rubricollis nests located on beaches that were being cleaned following anoil spill, both survived and edged young, after they were marked using signs and ropefences. In addition, cleaning crews worked for 20 minutes and then stopped for 20 minutesto allow adults to incubate the eggs. This study is also discussed in Clean birds followingoil spills.

(1) Ferrer, M. & Hiraldo, F. (1991) Evaluation of management techniques for the Spanish imperial eagle.Wildlife Society Bulletin, 19, 436 442.

(2) Morris, H., Blokpoel, H. & Tessier, G. D. (1992) Management efforts for the conservation of com-mon tern Sterna hirundocolonies in the Great Lakes: two case histories. Biological Conservation, 60,714.

(3) Dowling, B. & Weston, M. A. (1999) Managing a breeding population of the hooded plover Thinornisrubricollis in a high-use recreational environment. Bird Conservation International, 9, 255 270.

(4) Cobley, N. D. & Shears, J. R. (1999) Breeding performance of gentoo penguins (Pygoscelis papua) at acolony exposed to high levels of human disturbance. Polar Biology, 21, 355 360.

(5) Burger, J. & Leonard, J. (2000) Conict resolution in coastal waters: the case of personal watercraft.Marine Policy, 24, 61 67.

(6) Crouch, S., Paquette, C. & Vilas, D. (2002) Relocation of a large black-crowned night heron colony insouthern California. Waterbirds, 25, 474 478.

(7) Burger, J., Jeitner, C., Clark, K. & N, L. J. (2004) The effect of human activities on migrant shorebirds:successful adaptive management. Environmental Conservation, 31, 283 288. (8) Lafferty, K. D., Goodman, D. & Sandoval, C. P. (2006) Restoration of breeding by snowy plovers fol-

lowing protection from disturbance. Biodiversity and Conservation, 15, 22172230. (9) Medeiros, R., Ramos, J. A., Paiva, V. H., Almeida, A., Pedro, P. & Antunes, S. (2007) Signage reduces

the impact of human disturbance on little tern nesting success in Portugal. Biological Conservation,135, 99 106.

(10) Weston, M. A., Dann, P., Jessop, R., Fallaw, J., Dakin, R. & Ball, D. (2008) Can oiled shorebirds andtheir nests and eggs be successfully rehabilitated? A case study involving the threatened hoodedplover Thinornis rubricollis in south-eastern Australia. Waterbirds, 31, 127132.


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9.3. Set minimum distances for approaching birds (buffer zones)

We captured no intervention-based evidence for the effects on bird populations of setting min-imum distances for approaching birds.

Background

Disturbance by people on foot or in vehicles can reduce birds use of habitats, or drivethem into less favourable habitats. Preventing people from approaching birds too closelymay help reduce disturbance. We found two studies that investigated the distancesat which birds were disturbed by people: one found that people on foot disturbed

birds at greater distances than people in boats (Rodgers & Smoth 1995); the secondfound that different species reacted differently to disturbance (Rodgers & Schwikert2002). Both recommended buffer zones of between 100 and 180 m around breeding orfeeding birds.

Rodgers, J. A. & Smith, H. T. (1995) Set-back distances to protect nesting bird colonies from human dis-

turbance in Florida. Conservation Biology, 9, 89 99.Rodgers, J. A. & Schwikert, S. T. (2002) Buffer-zone distances to protect foraging and loang waterbirds

from disturbance by personal watercraft and outboard-powered boats. Conservation Biology, 16,216 224.

9.4. Provide paths to limit the extent of disturbance

A before-and-after study from the UK (1,2) found that two species of wader nested closer toa path, or at higher densities near the path, following resurfacing, which resulted in far fewer

people leaving the path.

BackgroundStudies have shown that visitors keep to paths when they are provided, thereby reducingdisturbance to the wider habitat without the need for specic access restrictions (e.g.Pearce-Higgins & Yalden 1997).

Pearce-Higgins, J. W. & Yalden, D. W. (1997) The effect of resurfacing the Pennine Way on recreationaluse of blanket bog in the Peak District National Park, England. Biological Conservation, 82, 337 343.

A before-and-after study from MarchJuly in 1986 1988 and 1996 1998 at a moor and bog

site within the Peak District, England (1), found that Eurasian golden plovers Pluvialis apri-cariaavoided a signicantly smaller area surrounding a path after it was re-surfaced, com-pared with before (birds avoided areas up to 200 m from the path before re-surfacing vs. areas50 m from the path afterwards; birds showed no avoidance on weekdays after re-surfacing).Before resurfacing, up to 30% of walkers left the path, afterwards only 4% left it. The studyfound no evidence that plover reproduction was adversely affected by disturbance aroundfootpaths.

A before-and-after study (2) using data from the same surveys as in (1) found that dunlinCalidris alpineoccupancy within 200 m of the footpath increased by 50% following path re-surfacing in 1994 (35 birds seen before resurfacing vs. 57 afterwards). However, the authors

caution that this was not a signicant increase, probably due to small sample sizes. The studyfound no evidence that dunlin reproduction was adversely affected by disturbance aroundfootpaths.

(1) Finney, S. K., Pearce-Higgins, J. W. & Yalden, D. W. (2005) The effect of recreational disturbance on anupland breeding bird, the golden plover Pluvialis apricaria. Biological Conservation, 121, 53 63.

(2) Pearce-Higgins, J. W., Finney, S. K., Yalden, D. W. & Langston, R. H. W. (2007) Testing the effects ofrecreational disturbance on two upland breeding waders. Ibis, 149, 45 55.


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Start educational programmes for personal watercraft owners 161

9.5. Reduce visitor group size

We captured no intervention-based studies examining the effects of reducing visitor numberson bird populations. However, a single, replicated study in forests in Spain in 2004 (1) found that

fewer birds, but not fewer species, were observed as visitor number increased. This effect

was largely due to decreases in collared dove Streptopelia decaoctopresence and serin Serinus

serinusabundance.

BackgroundLarger groups of visitors to sites will probably cause more disturbances, so limiting thenumber of people visiting at once may reduce detrimental impacts on birds.

(1) Remacha, C., Perez-Tris, J. & Antonio Delgado, J. (2011) Reducing visitors group size increases thenumber of birds during educational activities: Implications for management of nature-based recrea-tion,Journal of Environmental Management, 92, 1564 1568.

9.6. Use voluntary agreements with local people to reducedisturbance

A before-and-after trial in the USA (1) found significantly lower disturbance rates following the estab-lishment of a voluntary waterfowl avoidance area (VWAA), despite an overall increase in boat traffic.

BackgroundMany people will be willing to avoid certain areas or activities to help local bird popula-tions if they are consulted and kept informed about conservation issues. Under thesecircumstances, voluntary agreements to avoid birds may be at least as effective in reduc-ing disturbance as restricting access.

A before-and-after study 1986 in Lake Onalaska, Wisconsin and Minnesota, USA (1), foundthat disturbances to waterfowl within a voluntary waterfowl avoidance area (VWAA) estab-lished in 1986 decreased signicantly over time. Despite an increase in boating trafc (1.82

boating events/hour in 1986 8 vs. 2.58 in 1997), the 1997 disturbance rate were comparable tothat in 1981. Rate of intrusion into the VWAA was lower in 1997 (0.11 intrusions/boatingevent) than in either 1986 8 (0.18) or 1993 (0.21). Boating disturbances to waterfowl withinthe VWAA occurred at about half the rate (0.24 0.28 disturbances/hour) observed prior toestablishment of the programme (0.48 disturbances/hour). The total number of waterfowldisplacements observed as a result of boating events was 435,770 in 1993 and 71,155 in 1997.More than 90% of all waterfowl were observed within the VWAA.

(1) Kenow, K. P., Korschgen, C. E., Nissen, J. M., Elfessi, A. & Steinbach, R. (2003) A voluntary programto curtail boat disturbance to waterfowl during migration. Waterbirds, 26, 77 87.

9.7. Start educational programmes for personal watercraft owners

A before-and-after trial in the USA (1) found that rates of disturbance by personal watercraftdecreased and reproductive success of common terns Sterna hirundo increased following a

series of educational programmes aimed at recreational boat users.

BackgroundIt is possible that people will respond more positively to access restrictions or signs warn-ing them of disturbing birds if they are more aware of the issue. Educational programmesmay be able to help with this, informing the public of why certain actions are being taken.More general education programmes are discussed in Use education programmes andlocal engagement to help reduce pressures on species.


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A before-and-after trial from JulyAugust in 1997 8 in the waterways surrounding a commontern Sterna hirundonesting island in Barnegat Bay, USA (1), found that disturbance and repro-ductive costs caused by personal watercraft (PWC) disturbance signicantly decreased afterthe implementation of educational campaigns in late 1997. The proportion of PWCs movingpast the nesting island decreased from 60% in 1997 to 30% in 1998 and PWCs moved at sig-nicantly slower speeds. No PWCs went all the way around the nesting island in 1998. The

number of terns displaced by PWCs signicantly declined (from an average of 40 birds yingover the nesting island in 1997 to 20 birds in 1998). Fledging rate in 1998 was almost1 chick/nest, similar to before PWC inux (pre-1996). The educational campaign was aimedat local PWC rental businesses and owners and signs were posted around tern nesting islands.

(1) Burger, J. & Leonard, J. (2000) Conict resolution in coastal waters: the case of personal watercraft.Marine Policy, 24, 61 67.

9.8. Habituate birds to human visitors

A replicated, controlled study from Australia (1) found that bridled terns Sterna anaethetus in

heavily disturbed had similar or higher reproductive success compared with less-disturbed sites,possibly suggesting that habituation had occurred.

BackgroundDisturbance may well be more damaging to birds that are not use to humans. Therefore,habituating birds to the presence of human visitors may decrease nest abandonment ormortality, or increase reproductive success.

A replicated, controlled study from DecemberFebruary in 1995 8 on rocky islets in Queens-

land, Australia (1), found that bridled terns Sterna anaethetuson three high-disturbance siteshad similar reproductive success to birds on two low-disturbance sites, but that intermediate-aged chicks from the disturbed sites were signicantly heavier in one of two breeding seasons(average weight of 80 g for 12 13 day-old nestlings in the high-disturbance site vs. 80 g inthe low). The author argues that this may be caused by birds habituating to humans fasterat the heavily disturbed sites. High-disturbance sites were disturbed by visiting (3 6 people,variable walking speeds and noise levels). Visitation was 3 continuous hours/week or 3 1hours/week and disturbance regimes were rotated between plots. Low-disturbance sitesexperienced ambient disturbance during data collection and monitoring.

(1) Gyuris, E. (2003) An experimental investigation of the effects of human intrusion into breeding colo-nies of bridled terns Sterna anaethetus in the Great Barrier Reef. Pacic Conservation Biology, 9, 265 272.

9.9. Use nest covers to reduce the impact of research on predation ofground-nesting seabirds

A before-and-after study in Canada (1) found that protecting Caspian tern Sterna caspianestsafter researchers disturbed parents from them significantly increased hatching success. This was

due to a reduction in predation by ring-billed gulls Larus delawarensis.

BackgroundResearchers arriving at nesting colonies may disturb birds and, particularly with ground-nesting species, may leave them vulnerable to opportunistic predators. This predationmight be reduced by protecting the nests with cages or individual barriers.

Studies describing the more general use of nest cages and predator barriers are dis-cussed in Reduce nest predation by excluding predators from nests or nesting areas.


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Use nest covers to reduce the impact of research on predation of ground-nesting seabirds 163

A before-and-after study at a site on the South Limestone Islands, Lake Huron, Canada (1),found that the hatching rate in a Caspian tern Sterna caspiacolony was signicantly higher in1979 when researchers visiting the site added nest covers to nests when they arrived at thecolony and removed them as they left, compared to in 1978, when covers were not used (77%of 156 eggs hatching in 1979 vs. 62% of 188 in 1978). This difference was mainly due to largenumbers of eggs being eaten by ring-billed gulls Larus delawarensisin 1978. The author notes

that two eggs in 1978 were crushed by poor placement of the covers. Covers were 38 cm dia-meter hemisphere made from wood, steel and chicken wire.

(1) Quinn, J. S. (1984) Egg predation reduced by nest covers during researcher activities in a Caspian terncolony. Colonial Waterbirds, 7, 149 151.

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Bird Conservation: Global evidence for the effects of interventions. Contents and sample chapter

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