Nearly 28 years after the worst nuclear accident in history, several bird species are doing the seemingly impossible: flourishing inside the radioactive Chernobyl Exclusion Zone in Ukraine. Due to lingering radiation from the 1986 meltdown of the Chernobyl nuclear power plant, humans aren’t allowed to live there—but the region has become an accidental ecological testing ground for scientists interested in studying the effects of radiation on wild animals. Ionizing radiation damages living cells by producing free radicals, leading to genetic damage and, eventually, death. An animal’s only hope is to neutralize those free radicals by upping its production of antioxidants. And that’s exactly what most birds in Chernobyl seem to be doing—with even better results than scientists expected. A team of ecologists used nets to capture 152 birds from 16 species inside and around the 2600-square-kilometer exclusion zone. After assessing the birds’ antioxidant levels, amount of DNA damage, and body condition, the researchers were surprised to find that most of the birds, like the hawfinch pictured above, seemed to benefit from the chronic exposure to radiation. Birds found in areas with higher radiation levels had more antioxidants and better overall body condition, the team reports online this week in Functional Ecology. This is the first known example of wild animals adapting to chronic radiation exposure, the researchers say. The only two bird species negatively affected by the radiation—the great tit (Parus major) and barn swallow (Hirundo rustica)—both produce large amounts of pinkish pheomelanin pigment in their feathers. Because pheomelanin production requires lots of antioxidants, the researchers suspect these birds may not have enough left over to fight off the free radicals. In Chernobyl, it seems that fancy feathers come at a high price.