Habitat quality and habitat selection of golden-winged warblers in Costa Rica: an application of hierarchical models for open populations

Summary 1. Identifying high-quality habitat is integral to effective species conservation efforts and requires information about habitat-specific abundance and demographics. This information is lacking for many species of conservation concern because of the inherent difficulties associated with implementing mark–recapture studies at large spatial scales. 2. The golden-winged warbler Vermivora chrysoptera is a Neotropical–Nearctic migratory bird experiencing a long-term population decline; yet no information about non-breeding season habitat quality or habitat selection exists to inform conservation efforts. We used a novel hierarchical model that requires only spatially and temporally replicated count data to estimate habitat-specific abundance, apparent survival, recruitment and detection probability of golden-winged warblers wintering in Costa Rica. We quantified habitat selection at the home-range level using radiotelemetry. 3. Golden-winged warblers were absent from tropical dry forest and were most abundant in premontane evergreen forest. Within their home ranges, golden-winged warblers selected microhabitat features associated with intermediate disturbance that reflected their preference for foraging in hanging dead leaves. 4. Consistent with other evidence of a declining population, local population size decreased over the duration of the study. The rate of decrease was higher during the non-breeding season than among seasons. We found no differences in apparent survival or recruitment among habitat types; however, our estimates of these parameters were imprecise. 5. Synthesis and applications. Golden-winged warblers are forest-dependent species during the non-breeding season and have specialized microhabitat requirements that make them vulnerable to ongoing tropical deforestation. However, advanced secondary forests can provide the requisite microhabitat features, and because we found no evidence of reduced survival in this habitat type, regenerating forest on degraded lands may be an effective component of a conservation strategy for this species. Our study also demonstrates that information on population dynamics and habitat quality can be obtained using repeated counts instead of mark–recapture methods.