Habitat associations of Golden-winged Warblers and Blue-winged Warblers during the non-breeding season

Abstract

The Golden-winged Warbler (Vermivora chyrsoptera) and Blue-winged Warbler (Vermivora cyanoptera) are both Neotropical migratory species of elevated conservation concern that overlap in distribution on their Central American wintering grounds, yet the extent to which they overlap in terms of habitat use is unknown, potentially hindering conservation efforts. We surveyed these two species along habitat and elevational gradients within a coffee-growing landscape during 2016 and 2017 in Yoro, Honduras. We used playback with a mobbing track known to enhance detections of female warblers, since examining sexual habitat segregation was another objective of our study. Habitat occupied by these two species differed, with male Golden-winged Warblers occurring in landscapes dominated by humid forest/coffee (forest with some dense shade coffee, which were indistinguishable with remote sensing at our sites) at higher elevations than male Blue-winged Warblers, which were positively associated with the amount of agriculture in the landscape. Six of seven female Golden-winged Warblers were encountered in shade coffee, however, this association was not significant, likely due to small sample size and low detectability. The association between male Golden-winged Warblers and humid forest/coffee and elevation, and contrasts in habitat use between male and female Golden-winged Warblers, are consistent with prior research in the region. Furthermore, the landscape associations of these non-breeding Vermivora species mirror their breeding landscape associations, with Golden-winged Warblers occupying more forested landscapes and Blue-winged Warblers occupying more agricultural landscapes. The use of shade coffee by female Golden-winged Warblers and Blue-winged Warblers suggests agroforestry could be a promising tool for conserving wintering populations of these species, although this result should be viewed with caution given that use of shade coffee is reported to elevate predation risk in other migratory species, and may not provide habitat for forest-dependent resident birds.