Cavity Nest Preferences and Locations of Woodpeckers in Wild Basin, Rocky Mountain
National Park
Peter DolanWinter Ecology, Spring 2012
Mountain Research Station, University of Colorado at Boulder
Ecological Importance
• Cavities can aid birds in thermoregulation–Wind and Sun Exposure
(Rendell and Robertson 1994)
• Snags and primary cavity nesters are critical to the stability of forest ecosystems (Wiebe, 2001)
Research Site
Research Questions
• What are the determining factors for woodpeckers in choosing a tree to use as a potential nest at Wild Basin?
• Where on a tree do woodpeckers create cavity nests and why?
Woodpeckers
Hairy WoodpeckerDowny Woodpecker
Northern Flicker
Research Methods
• Early set backs (questioning my methods)
• Scouting for snags• Document variables of cavity
locations– Tree Species– Cavity Aspect– DBH (diameter at breast height)– Cavity Height
Field Results
0 1 2 3 4 5 6 7 8 90
10
20
30
40
50
60
70
80
DBH of Observed Cavity Trees
Observed Cavity Trees
DBH
(cm
)
Mean DBH observed: 47.2North
South East
West NE
NW SE SW
1
2
3
0
4
2 2
4
Cavity Aspect
Discussion
• Cavity Aspect Hypothesis• Cavities faced open areas rather than dense
forest• Why were there no cavities in subalpine fir
snags?
Results Compared to Prior Research
• Hairy Woodpeckers nest in what ever habitat is available (Ripper et al, 2007)
• Broken canopy is a key variable in determining a tree in which to nest (Ripper et al, 2007)
• Prefer to nest in older trees with large DBH, in relatively open forest areas (Ripper et al, 2007)
Conclusions
• Importance of primary cavity excavators in forest ecosystems
• Cavity aspect • Broken Canopy and a large DBH are key
variables in choosing a nesting tree
Works Cited
• Landscape Use by Hairy Woodpeckers in Managed Forests of Northwestern Washington. Dana Ripper, James C. Bednarz and Daniel E. Varland The Journal of Wildlife Management , Vol. 71, No. 8 (Nov., 2007), pp. 2612-2623.
• Cavity-Entrance Orientation and Nest-Site Use by Secondary Hole-Nesting Birds Wallace B. Rendell and Raleigh J. Robertson Journal of Field Ornithology , Vol. 65, No. 1 (Winter, 1994), pp. 27-35.
• Microclimate of Tree Cavity Nests: Is It Important for Reproductive Success in Northern Flickers? Karen L. Wiebe The Auk , Vol. 118, No. 2 (Apr., 2001), pp. 412-421.