Habitat-specific survival of golden-winged warblers (Vermivora chrysoptera) during the non-breeding season in an agricultural landscape

Nearctic-Neotropical migratory birds are considered priority species for
conservation because they are subject to threats at distinct breeding,
migratory and stopover locations throughout their annual cycle, and many
species have undergone severe population declines. Research during the
non-breeding season has focused on identifying the locations and habitats
that migrants use, but wintering migrants are known to occupy habitats of
both high and low quality, especially when the best sites are saturated by
conspecifics. Thus, the presence or abundance of a species may not be a
reliable indicator of winter habitat quality. The habitat associations of
the golden-winged warbler Vermivora chrysoptera, a Nearctic-Neotropical
migrant bird species of elevated conservation concern, are relatively well
studied, yet conservation efforts are hindered by lack of information
about basic demographic rates. In particular, no published estimates exist
for non-breeding season survival, which can be a key vital rate affecting
population viability, nor how survival rates vary among habitats, which is
important to designing conservation programs to support populations during
the winter period. We studied a color-banded population of golden-winged
warblers in Costa Rica over a 3-year period and estimated overall survival
rates, and the effects of habitat characteristics on survival. We found
that monthly survival of juveniles (0.881) was lower than adult birds
(0.978). Monthly survival during the non-breeding season (0.967) was
higher than monthly survival during the rest of the annual cycle (0.930).
Survival was negatively related to canopy height, and we observed a
significant quadratic effect where survival peaked at intermediate levels
of vine tangles and dead hanging leaves, which corresponds to habitat
features associated with abundance in prior studies at this same site. Our
findings contribute to our existing knowledge about the potential impacts
of winter-season events on Nearctic-Neotropical migratory bird
populations, and also informs potential conservation strategies for
wintering golden-winged warblers.