Influence of Postfire Salvage Logging on Black-Backed Woodpecker Nest-Site Selection and Nest Survival

摘要

Post-fire timber harvest practices (i.e. post-fire salvage logging) on public lands are a highly contentious issue in the western United States. Harvest of burned trees impacts a number of species, particularly those specialized for using post-wildfire habitats. We assessed the effects of post-fire salvage logging on black-backed woodpecker (Picoides arcticus) nest-site selection and nest survival within burned, mixed conifer forests of south-central Oregon. Multiple treatment and control plots were surveyed two years pre-logging (2003-04) and two years post-logging (2005-06). Our objectives were to (a) examine the effects of salvage logging on black-backed woodpecker nest site selection and nest survival at coarse and fine spatial scales (b) elucidate additional habitat and abiotic factors predicting black-back nest occurrence and survival, and (c) determine if those habitat covariates influencing nest site selection coincide with those influencing nest survival. A total of 210 black-backed woodpecker nests were monitored during the four year postfire period. Postfire salvage logging did not significantly reduce snag numbers or diameters within treatment units. Based upon our best nest-site selection model, black-backed woodpecker nest locations were different from non-nest points in habitat characteristics at both fine and coarse spatial scales, with variables related to surrounding snag density being the strongest predictors. Black-backed woodpeckers exhibited high overall nest survival (78.5%; 95% CL = 0.6996, 0.8495). Nest survival models containing temporal predictors (i.e. Julian date) received more support than those related to salvage harvest or other habitat features. Factors influencing black-backed woodpecker nest-site selection were not same as those affecting nest survival, suggesting a lack of adaptive nest-site choice in terms of nest survival. Our results correspond with past studies outlining the importance of high-density snag areas for woodpecker nesting. Maintaining complete snag species composition and high snag densities will help conserve black-backed woodpecker nesting habitat in the early years following stand-replacement wildfire.