Impaired resilience to climate change in Chornobyl barn swallows

1. Global warming and degradation of natural habitats are the two main factors causing ecophysiological stress on individuals and risk for biodiversity. Hyperthermia is a common response to stress in homeothermic animals, in particular to heat, pathogens and environmental contamination. 2. Resilience of biological systems to global warming may be deteriorated in polluted habitats. Here we investigated how body temperature of a wild bird, the barn swallow (Hirundo rustica), responded to global warming while simultaneously exposed to radioactive contamination from Chernobyl accident. 3. Our results showed that both rising air temperatures and environmental radioactive contamination increased internal body temperature of individuals. Importantly, global warming and radioactive contamination both lead to hyperthermia, which in turn is associated with reduced fecundity thus posing a risk to population growth rates. 4. Our results suggest that local habitat contamination can hamper resilience of wild animals to rising temperatures, and that contamination directly and indirectly impairs animal performance. The cumulative and interactive negative effects of multiple stressors, such as those emerging from increasing habitat degradation and climate change, will likely accelerate biodiversity losses globally.