Effects of salvage logging of beetle‐killed forests on avian species and foraging guild abundance

Abstract

AbstractEvaluating spatial and temporal variation in abundance due to anthropogenic and environmental disturbances is a central aspect of wildlife ecology and management. We conducted an experiment to evaluate the effects of salvage logging on the abundance of 22 avian species and 6 foraging guilds in lodgepole pine (Pinus contorta) forests affected by beetle outbreaks, south‐central Oregon, USA, 1996–1998. Treatments consisted of the removal of lodgepole pine snags only; live trees and ponderosa pine snags were not harvested. Our hierarchical model requires replicated count data from multiple sample units across several time periods, during which the population is closed, to estimate abundance as a function of logging treatment and management district while accounting for imperfect and variable detection probability. We fit the model to point counts from 12 control and 12 treatment plots with 3 surveys during each breeding season, 1996–1998. We found evidence for a large, but imprecise, effect of salvage logging in all 3 years for only 1 species, the gray flycatcher (Empidonax wrightii). The abundance of the remaining species either did not change or displayed weak positive responses to the treatment. Although 3 foraging guilds increased in total abundance, 2 guilds did not change and the response of 1 guild changed direction in different years. Our results suggest that, unlike most postfire salvage logging prescriptions, selective harvesting after beetle outbreaks may meet multiple management objectives, including the maintenance of avian population sizes comparable to those found in unharvested stands. Future research should consider different sampling programs for those species with large home ranges (e.g., woodpeckers) that may not be sampled adequately using commonly employed programs (e.g., point count stations). © 2012 The Wildlife Society.