Impacts of Aspen and Conifer Vegetation on Predation Risk and Distributions of Bird Species

Abstract

Aspen forests are in decline around the globe and are largely being replaced by conifers.  Associated with this shift in forest composition, we document an increase in nest predation risk and decrease in abundance of bird species that breed in aspens.  These observational data from 5 years across 19 forest stands in western Montana were verified with an adaptive management experiment removing all conifers from three large aspen stands in the Mt. Haggin WMA.  This landscape-scale approach strongly supports the active management of aspen stands, by such methods as removing conifers, to improve breeding bird habitat.  Our results also suggest that vegetation-mediated effects of predation are associated with avian distributions and species turnover.