Wood Thrush ( <i>Hylocichla mustelina</i> ) occupancy patterns reveal sensitivity to low precipitation on nonbreeding grounds in northern Costa Rica

Climatic change and anthropogenic disturbances are reshaping animal populations. Habitat loss and extreme climatic events are particularly strong drivers of declines in species that depend on forested areas. For migratory songbirds, climate and the persistence of suitable habitat over time are fundamental to sustaining populations annually. In Neotropical regions, habitat requirements during the nonbreeding season remain poorly understood for many migratory birds. In this study, we examined factors influencing occupancy of the Wood Thrush Hylocichla mustelina , a species that has experienced alarming population declines in recent decades. Specifically, we tested whether forest structure, precipitation or both explained its occupancy within a large protected area in Costa Rica, the Área de Conservación Guanacaste (ACG). We deployed autonomous recording units in 71 stations within 12 sites for four consecutive days to detect Wood Thrush vocalizations and estimate its occupancy. The sites spanned dry, wet and cloud forest along elevational and precipitation gradients in ACG. Sampling occurred from 0500 to 0730 h during two nonbreeding seasons: December 2022–February 2023 and October–November 2023. At each station, we measured forest structure variables (canopy openness, leaf area index (LAI), basal area, understorey cover and palm abundance) and obtained daily precipitation from meteorological stations. We modelled single season occupancy and found that Wood Thrush was positively associated with precipitation in both seasons, consistent with a preference for wetter conditions within a continuous forest landscape. During the season December–February, its occupancy increased at stations with high basal area in interaction with higher precipitation. The effect of precipitation on Wood Thrush occupancy may reflect greater prey availability in wetter habitats than in drier locations. As climate change reduces moisture availability, its habitat suitability in nonbreeding grounds could decline. Our findings highlight the importance of wetter habitats within protected areas for Wood Thrush and other migratory and resident forest‐dependent bird species on the nonbreeding grounds.