Climate change is a threat to biodiversity and animal populations around the world. Underscoring this general threat, bird species populations have been declining dramatically over the past few decades, and any effects of climate on avian annual survival will have important implications for their population trends. Climate cycles like the El Niño Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO) are predicted to become more extreme as the climate changes, but the effects of climate cycles on animal populations remain uncertain. Here, we use 20 years of mark-recapture data from across the continental United States to evaluate the influence of climate cycles on annual survival rates of 49 bird species. We used data from the Monitoring Avian Productivity and Survivorship (MAPS) network collected during the breeding seasons of 1992-2012 to estimate changes in annual apparent survival and to test whether ENSO and NAO influence annual survival rates for 49 passerine species.
Results/Conclusions
ENSO and NAO have a coordinated continental-scale effect on annual survival of bird species. ENSO and NAO have a significant effect on annual survival for approximately 80% of species studied. These continental-scale results strongly suggest that migratory and resident bird species populations are at substantial risk due to higher variability in these climate cycles predicted to be caused by climate change. Climate cycles are likely influencing survival rates by affecting migration efficiency or by causing phenological mismatches and longer stopover times during migration. Responses of migratory and resident birds to climate phenomena are also likely to have carryover effects on reproductive success, calling for more focus on population trends for species of conservation concern.