Effects of regent burning on breeding bird community structure in aspen forests

Fire is an important disturbance that stimulates aspen regeneration and exp ansion in the western United States. We investigated the impacts of burning aspen-dominated habitats on landbird community structure in the western fo othills of the Wind River Range, Wyoming. Habitat structure, breeding bird species composition, richness, and relative abundance were compared in 1994 and 1995 between six independent pairs of sites, each pair consisting of a recently burned aspen site and a control site. Burned sites typically had lower canopy cover and depth, greater snag densities and aspen regeneration , and less shrub growth. We observed 45 diurnal woodland bird species overa ll. Western Wood-Pewees (Contopus sordidulus) and Warbling Vireos (Vireo gi lvus) were detected significantly less often in the burned sites, while Mou ntain Bluebirds (Sialia currucoides) and Pine Siskins (Carduelis pinus) wer e detected significantly more often in the burned sites. Orange-crowned War blers (Vermivora celata), Red-naped Sapsuckers (Sphyrapicus nuchalis), and chickadees (Poecile spp.) were significantly less abundant in the burned as pen when burn size or year was factored into the analysis. For many other c ommonly detected species, we had relatively low power to detect meaningful differences in abundance between recently burned and unburned aspen stands. Bird species richness was similar between treatments. Bird species composi tion differed consistently among burned-control pairs, but our data suggest ed that intersite variability in species composition in aspen is the norm i n the absence of burning.