Characterization of golden-cheeked warbler Dendroica chrysoparia habitat at Fort Hood, Texas, USA

摘要

The golden-cheeked warbler Dendroica chrysoparia is a federally endangered, neotropical-nearctic migrant songbird that breeds in central Texas, USA, and prefers mature, closed canopy oak–Ashe juniper woodlands for nesting and foraging. Fort Hood is an 87 890 ha military reservation located in central Texas in Bell and Coryell Counties on the eastern edge of the Edwards Plateau ecoregion. We surveyed for golden-cheeked warblers and measured habitat variables at 95 separate locations in a 56.6 km2 research area that supports a golden-cheeked warbler breeding population. We detected golden-cheeked warblers on 34 of 95 (36%) point count locations. Principal component analysis was used to reduce the 27 habitat variables to a set of uncorrelated variables. This analysis resulted in the identification of 4 principal components that accounted for 52% of the variance. Logistic regression identified one principal component (ratio of Ashe juniper to other woody species) that was strongly related to golden-cheeked warbler occurrence. Our data indicate that a 4:1 ratio of Ashe juniper to other woody species is an important feature of occupied golden cheekedwarbler habitat, particularly in the mid- to upper canopy at Fort Hood.