Ecological differences in response of bird species to radioactivity from Chernobyl and Fukushima

Organisms differ in their susceptibility to ionizing radiation, although the ecological basis for such differences remain poorly understood. We hypothesized that ecological characteristics such as body size, diet, migration and pigments of plumage would predict the impact of radiation on abundance through effects on relative food consumption rates, free radicals and antioxidants. We made 2,398 breeding bird censuses and quantified the impact of radiation on abundance at Chernobyl and Fukushima providing statistical replication, but also analyses of interaction effects. The impact of radiation on abundance of birds was stronger at Fukushima than at Chernobyl. Species with small body size and hence relatively high food consumption rates were more negatively impacted. Secondary consumers showed stronger negative effects of radiation on abundance than herbivores, especially at Fukushima. There was no main effect of migration, but migrants were more negatively impacted at Chernobyl, while residents were more negatively impacted at Fukushima. Carotenoid and pheomelanin plumage pigments associated with antioxidant status showed stronger negative effects, especially at Chernobyl compared to Fukushima, while eumelanic coloration which is not related to antioxidant status did not show such an effect. These differences between Chernobyl and Fukuskima may reflect differences in duration of exposure, differences in radioactive isotopes and differences in accumulation of mutations.