LAUSR

Abstract Understanding how geographic variation in environmental conditions influences species’ distributions and population dynamics is critical for effective management of at-risk species and can help us anticipate wildlife responses to future change. The Golden-cheeked Warbler (Setophaga chrysoparia; hereafter warbler) is an endangered migratory songbird that nests in oak-juniper woodland in Texas. From 2009 to 2013, we monitored 895 warbler territories at 90 study sites located across the warbler’s breeding range to examine how geographic variation in vegetation characteristics influenced aspects of warbler habitat selection and productivity. We found range-wide variation in the tree species composition and vegetation structure of warbler habitat. Warbler territory density decreased with increasing percent Ashe juniper (Juniperus ashei) canopy cover at study sites predominated by shin oak (Quercus sinuata) and increased with increasing percent Ashe juniper canopy cover at study sites predominated by post oak (Q. stellata), but did not vary in relation to percent Ashe juniper cover at study sites predominated by other oak species. We also found that territory size decreased with increasing percent canopy cover (all tree species), but did not find evidence that warbler pairing success or fledging success varied in relation to the vegetation characteristics of our study sites. Our results suggest that warblers breed under a wider range of conditions than identified in current management guidelines and that warbler management guidelines could be more effective if developed and applied at local or regional scales. Our study also reiterates the importance of understanding geographic variation in wildlife-habitat relationships for conservation of at-risk species.