Nest survival in experimentally created snags on a managed forest landscape
Matthew Hane, Andrew Kroll, Josh Johnson, Mike Rochelle and Ed ArnettAOU/COS Conference | Chicago, IL | August 2013
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Creating snag habitat from live trees can be done
• Background
• Study Design
• Results
• Final Thoughts
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Background
• Transition from naturally regenerated to intensively-managed stands
• Deficiencies in snag numbers and types
• How will adequate types and numbers of snags be maintained in upland areas?
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Background
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• 2008 through 2010
• Determine rate of avian nest survival in snags created from merchantable 2nd growth
Study Design
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• Two stage modeling processo 1st temporal variation
date, date^2, stage, date*stage, constant, globalo 2nd experimental design
year, treatment, density, dispersion, density*dispersion, area
• Logistic exposure methodShaffer, Terry L. (2004) A unified approach to analyzing nest success. Auk, 121, 526-540.
Study Design
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Yearly weather variation
Study Design
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•"Industrial tree farms are sterile and lifeless, this particular method is incredibly ecologically destructive." Juliette Beck, coordinator of the Sierra Club's Stop Clearcutting Campaign, as quoted in the San Francisco Bay Guardian Online November 9, 2011•" … conversion of naturally regenerating stands to plantations may lower nesting success … " Vander Haegen and De Graff (1996)•Sallabanks and Arnett (2001) reviewed bird forestry relationships.
Results - Expected
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Walter & Maguire (2005) Snags, cavity nesting birds, and silvicultural treatments in western Oregon. Journal of Wildlife Management, 69, 1578-1591
Results - Expected
Primary cavity excavatorsChestnut-back chickadeeDowny woodpeckerHairy woodpeckerNorthern flickerPileated woodpeckerRed-breasted nuthatchRed- breasted sapsucker
Secondary cavity excavators
Brown creeperEuropean starlingHouse wrenViolet-green swallow
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Results Nest Totals 2008-2010
2008 2009 2010Total
Failed Successful Failed Successful Failed Successful
CBCH 15 54 39 78 51 59 295
HOWR 9 27 10 41 4 17 108
NOFL 9 12 6 15 8 13 63
PUMA 0 6 5 4 2 3 20
HAWO 1 2 2 1 6
WEBL 2 1 1 4
RBSA 1 1 1 3
NSWO 1 1 2
RBNU 2 2
VGSW 2 2
Total 38 105 60 142 68 93 506
Yearly Success 73% 70% 58% 67%
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Results Chestnut-back chickadee
•Our Studyo Apparent nest success 65%o Average daily survival 0.989 95%CL:
0.965-0.996
•Other Studieso Mahon & Martin (2006) 49%o Sperry et. al. (2008) 0.976 & 0.984
o Breeding Bird Survey Trend:
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Results House wren
•Our Studyo Apparent nest success 78%o Period survival 0.72 95%CL:
0.52, 0.85
•Other Studieso Period survival rate
o Cavities 0.63 – 0.75o Boxes 0.83
o Breeding Bird Survey Trend:
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Results Northern flicker
•Our Studyo Apparent nest success 64%o Period survival rate 0.60 95%CL: 0.46,
0.71
•Other Studieso Apparent nest success
cavities and boxes 41% - 100%o Period survival rate 0.41 – 0.80o Breeding Bird Survey Trend:
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Results Purple martin
•Our Studyo Apparent nest success 65%o Period survival rate 0.70 95%CL: 0.48,
0.84
•Other Studieso Nest box success 39% - 84% o Breeding Bird Survey Trend:
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Final Thoughts
• Leaving created snags at a density of ~ 0.5/ha retains some cavity-nesting bird specieso Up to years 12-15…
• Benefits restricted by rotation ageo Snags must be created from trees growing in unito Suitability is also dependent on stand conditions and
landscape context
• Different strategies are required to provide tall snags
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THANK YOU
