Potential resilience of forest birds in the Appalachian Mountains to future climate change during the breeding season

Global climate change is predicted to cause long-term changes in bird distributions and populations. Although previous studies often prioritized understanding avian responses to shifting climate conditions, recent efforts increasingly incorporate landscape change as an additional factor. We evaluated current and potential future effects of both climate and landscape change on the breeding distributions and relative abundance of 14 forest songbird species in the Appalachian Mountains. For each species, we compiled route-level total count data from 322 North American Breeding Bird Survey routes that were sampled between 1997–2017. Using Bayesian modeling techniques, we determined the relative influence of temperature, precipitation, and proportions of land cover types on route-level annual total species counts. We then projected future changes in relative abundance, regional occupancy, and distribution of relative abundance from 2000 to 2100, based on multiple greenhouse gas emission scenarios. Our models showed that proportions of land cover types tended to be more influential and had higher effect sizes than climate variables on forest songbird relative abundance during the breeding season. In our future predictions, most changes in relative abundance and regional occupancy were modest. These results indicated that net projected impacts of climate change on the 14 focal forest songbird species during the breeding season were minimal at a broad scale in the Appalachian Mountains. Instead, land use changes that result in reduced forest cover and increased urban cover may pose a more immediate threat than climate change to forest songbirds breeding in this region.