Demographic responses of eastern bluebirds to climatic variability in northeastern Arkansas

摘要

As climate change continues to alter temperature and precipitation patterns, numerous species have declined. However, populations of some species that show responses to climate change, such as eastern bluebirds (Sialia sialis), have increased or remained stable nationwide. To understand how species are adapting to climate change, we estimated demographic parameters and their responses to climatic variability, using nesting and banding-recapture data between 2003 and 2018 in a northeastern Arkansas eastern bluebird population. Increasing variability in precipitation in the nonbreeding season negatively affected hatchability. Hatching success was negatively affected by increasing variability in maximum temperatures and the number of hot days during the breeding season, but positively affected by increasing winter snow depth. Adult survival was positively affected by increasing snow depth and variability in the number of hot days during the breeding season, but negatively affected by increasing variability in nonbreeding season temperatures. Our results demonstrate that for this study population, annual breeding parameters, though canalized against interannual environmental variation, were affected by seasonal climatic variability. Although climate change may benefit bluebird survival due to increasing variability in winter temperatures and the number of hot days, climatic variability negatively affected breeding parameters and is expected to increase. Because breeding parameters are typically the drivers of population growth rate in short-lived species, these results raise concern for the future of this population of eastern bluebirds.