Can patterns of habitat use by western Nearctic–Neotropical migratory landbirds in winter inform conservation priorities?

Abstract

I use point-count survey data collected from 171 locations across 11 vegetation conditions in western Mexico to illustrate common patterns of winter habitat use by 97 Nearctic–Neotropical migratory landbird species. A number of bird species are relatively restricted in their habitat use, with some (e.g., Northern Waterthrush [Parkesia noveboracensis], American Redstart [Setophaga ruticilla]) occurring only in relatively undisturbed habitats, and others (e.g., Say's Phoebe [Sayornis saya], Horned Lark [Eremophila alpestris]) occurring only in relatively disturbed lands associated with agriculture. A large number of bird species (e.g., Cassin's Vireo [Vireo cassinii], MacGillivray's Warbler [Geothlypis tolmiei]) use every one of the vegetation types considered, from low-elevation tropical deciduous forests to high-elevation conifer forests. Bird species showing patterns of restricted habitat use deserve conservation attention, but even the more broadly distributed species might become significantly less abundant in human-altered portions of habitats. Identifying the latter will require the inclusion of a wider spectrum of altered vegetation types/conditions than what I included here, or than what is typically considered in wildlife–habitat relationship programs.