Threat of climate change on a songbird population through its impacts on breeding

Understanding global change processes that threaten species viability is critical for assessing vulnerability and deciding on appropriate conservation actions(1). Here we combine individual-based(2) and metapopulation models to estimate the effects of climate change on annual breeding productivity and population viability up to 2100 of a common forest songbird, the Acadian flycatcher (Empidonax virescens), across the Central Hardwoods ecoregion, a 39.5-million-hectare area of temperate and broadleaf forests in the USA. Our approach integrates local-scale, individual breeding productivity, estimated from empirically derived demographic parameters that vary with landscape and climatic factors (such as forest cover, daily temperature)(3), into a dynamic-landscape metapopulation model(4) that projects growth of the regional population over time. We show that warming temperatures under a worst-case scenario with unabated climate change could reduce breeding productivity to an extent that this currently abundant species will suffer population declines substantial enough to pose a significant risk of quasi-extinction from the region in the twenty-first century. However, we also show that this risk is greatly reduced for scenarios where emissions and warming are curtailed. These results highlight the importance of considering both direct and indirect effects of climate change when assessing the vulnerability of species.