Title

Home Range Size and Foraging Habitat of Black-Backed Woodpeckers

Publication Date

4-2005

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Biology

Department

Biology

Major Advisor

Victoria A. Saab

Abstract

I examined home range size and foraging habitat of Black-backed Woodpeckers (Picoides arcticus) in southwestern Idaho during 2000 and 2002 (6 and 8 years following fire). Home range size for four adult males during the post-fledging period was 115.6 - 420.9 ha using the 95 % Fixed Kernel method, and 150.4 - 766.1 ha using the 100 % Minimum Convex Polygon method. Smoothed bootstrap estimates (95 %) were 130.0- 521.9 ha. Home range sizes were significantly smaller at 6 years after fire than those 8 years after fire. I used logistic regression to model foraging habitat selection by Black- backed Woodpeckers at multiple spatial scales: microhabitat (local habitat characteristics surrounding foraging trees/snags), macrohabitat (patch characteristics within home ranges), and landscape (composition of habitat features within the bums and surrounding green forest). High mean tree/snag densities were positively associated with foraging locations at the microhabitat scale, and both tree/snag density and diameter were important in models. Douglas-fir (Pseudotsuga menziesii) may have been preferred because it tends to support beetle prey during later years post-fire. Percent live trees and mean log cover were inconclusive as predictor variables. At the macrohabitat scale, results reflected the variation of habitat features within home ranges. High or moderate crown closures were positively associated with foraging locations and ponderosa pine (Pinus ponderosa) cover type tended to be negatively associated with foraging locations. Large patch area based on cover type-crown closure, low bum severity, and close proximity to moderate and high crown closures were important for predicting foraging locations. Black-backed Woodpeckers selected landscapes for foraging that contained high crown closure, and to a lesser extent for most males, moderate crown closure. If those landscapes were burned, Black-backed Woodpeckers selected for moderate bum severity. Unburned forest adjacent to the bums was important for two males and implies that bums are less suitable for foraging 6 and 8 years after fire. Douglas-fir or mixed ponderosa pine/Douglas-fir cover types were generally preferred, but not always; subalpine fir (Abies lasiocarpa) was not used. I provide recommendations for maintaining foraging habitat of Black-backed Woodpeckers at multiple spatial scales.

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