Local-scale Habitat Components Driving Bird Abundance in Eastern Deciduous Forests

Abstract

Declining populations of forest songbirds in the eastern U.S. have emphasized a need for scientists and managers to understand habitat selection by birds in remnant patches of contiguous forest. Past work has identified effects of landscape-scale covariates on bird occurrence and abundance; however, less is known about the effects of local-scale forest structure. We applied a combination of forest inventory data and LiDAR-derived canopy height data to derive variables of local-scale forest structure in a managed forest. We then assessed the effects of these variables on the abundance of 18 forest bird species obtained from point counts, while accounting for imperfect detection using a combined distance and time-removal model. We found mean canopy height and terrain variables including elevation, slope, and aspect affected the local-scale abundance of the largest number of bird species and also had the largest effect sizes. Variables associated with vertical structure of the canopy were not important predictors of abundance. Our results confirm the importance of canopy height and terrain on abundance of multiple forest songbirds and emphasize the value of fine-scale spatial data for assessing bird habitat use.