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 NENW 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.