Broad-scale habitat use by fledgling black-capped vireo

Abstract

Knowledge of avian habitat associations during the postfledging stage is lacking for most songbirds, which limits the ability to develop and implement management plans that address the full life cycle of birds. The Black-capped Vireo (Vireo atricapilla; hereafter vireo) is a Neotropical migratory songbird that breeds in early to mid-successional vegetation but has been documented using late-successional vegetation. We used data collected in 2013 and 2014 to determine the spatial distribution of vireo fledglings in relation to the availability of woodland cover in central Texas. We found that woodland cover was used less often than it was available in the landscape. We used a model selection approach with generalized linear mixed models and generalized additive mixed models to determine which variables, i.e., age (days since fledging) or season (days since the first nest at the study site fledged young), best explained vireo fledgling use of woodland and distance from fledgling locations to woodland. The probability of woodland use by fledglings was best predicted by season, and fledglings were located closer to woodland vegetation as the season progressed and as fledglings aged. The lack of selection for woodland cover by vireo fledglings and their persistent use of shrub-dominated cover suggest that the shrubdominated cover provides analogous resources to those used by adults during the breeding season. Fledglings also use woodland cover where available and move toward the shrubland-woodland interface over time, suggestive of a possible function of woodland vegetation as postfledging habitat. Thus, land managers should consider the impact of land management practices in woodland and shrubland cover on the habitat availability for Black-capped Vireo throughout its life cycle, and on other migratory species.