Masters Thesis

Avian nest survival in post-logging coastal buffer strips on Prince of Wales Island, Alaska

I examined the effect of forest buffer width and nest site characteristics on the nest survival of forest birds on Prince of Wales Island, Alaska. During 2002 and 2003, a total of 164 nests of three closed cup (Chestnut-backed Chickadee (Parus rufescens), Red-breasted Sapsucker (Sphyrapicus ruber) and Winter Wren (Troglodytes troglodytes)) and four open cup (Pacific-slope Flycatcher (Empidonax difficilis), Hermit Thrush (Cartharus guttatus), Swainson’s Thrush (Cartharus ustulatus) and Varied Thrush (Ixoreus naevius)) species were monitored within forested buffers along the coastline. I modeled daily survival rate (DSR) of closed (DSR = 0.989) and open (DSR = 0.982) cup nesting species independently using variables at two spatial scales. For closed cup nests the model best describing variation in DSR included height of nest and species. Nests located higher from the ground had better nest success. Variation in DSR of open cup nests was best explained by species. Pacific-slope Flycatcher nests had the highest success (87%) whereas Varied Thrush nests had the lowest (21%). DSR of Hermit Thrush nests, the only species for which I had adequate data to analyze separately, was related to distance to the coastline. Species with low DSR had similar nest site characteristics including diameter of nesting substrate and average percentage concealment of nest. However, these nest site characteristics alone do not determine DSR of the species evaluated in my study. Width of coastal forested buffers appears to have a negligible effect on DSR, however, some species exhibited low DSR within the buffers and further examination of these species is recommended.

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