The researchers -- led by Anders Moller of the University of Paris and Professor Timothy Mousseau of the University of South Carolina -- said their findings help explain why some species are more affected by ionizing radiation than are others.

The researchers examined 1,570 birds from 57 different species in the forests around Chernobyl at varying distances from the damaged reactor.

"We found that bird species differed in their response to radiation from Chernobyl," said Moller and Mousseau. "The strongest declines in population density with radiation level were found for species with carotenoid-based plumage, long-distance migration and dispersal, and large eggs for their body size.

"All four of these factors are associated with anti-oxidant levels, suggesting reduced anti-oxidant levels may cause population declines when species are exposed to radiation."

The study is detailed online in the British Ecological Society's Journal of Applied Ecology.