Some birds adapt to Chernobyl’s radiation

On April 26, 1986, the world saw the worst civilian nuclear disaster in history when Unit 4 of the nuclear power station in Chernobyl, Ukraine, was destroyed. The explosion and subsequent fire released radioactive material into the environment that lingers today. The Soviet government closed off a 30-kilometer area around the plant, and hundreds of thousands of people were evacuated, never to return home. Workers are still trying to cap the site with a giant arch that would entomb the remains of the nuclear reactor.

The effects on local plants and wildlife have been varied. Pine trees close to the disaster died in the days soon after. Other plants thrived in the spaces abandoned by humans. Wildlife, too, seemed to be doing well. Rare birds were spotted. A herd of Przewalski’s horses, escaped from captivity, grew. Wolves and boar were seen on the streets of one town.

But all was not good. Radiation, after all, is not healthy for living things. And so studies have documented negative effects of Chernobyl’s radiation on the region’s plants and animals, including changes in abundance, distribution, life history and mutation rates. Scientists have found that birds living in the area have eye cataracts or smaller brains. And insects, microbes and other decomposers aren’t behaving normally.

A new study, however, finds that some birds may be adapting to the low levels of radiation that persist around Chernobyl. The study was published April 24 in Functional Ecology.

Ismael Galván of Paris-Sud University and colleagues captured 152 birds representing 16 species from sites within and near the Chernobyl exclusion zone. They took blood samples and analyzed the birds’ levels of antioxidants, how much their DNA had been damaged and their body condition. They also measured the levels of the pigment pheomelanin in the birds’ feathers.

When the researchers compared birds captured in higher radiation areas with those in lower radiation spots, they found something surprising: The birds from the higher radiation zones were generally in better condition, and they had higher levels of antioxidants. These molecules can help cells by stopping the reaction through which ionizing radiation damages DNA.

“To our knowledge, this represents the first evidence of adaptation to ionizing radiation in wild populations of animals,” the researchers write.

Two species, great tits (Parus major) and barn swallows (Hirundo rustica) didn’t follow the pattern and were doing worse in the high radiation locations. These birds had higher levels of pheomelanin in their feathers. Antioxidants are consumed in the production of pheomelanin, so to produce higher levels, the birds would have used up more antioxidants. Perhaps, the researchers write, these birds aren’t left with enough antioxidants to effectively deal with the DNA damage caused by radiation.

However, anyone thinking that this is good news for Chernobyl’s wildlife should think again. “The effects of radiation at Chernobyl on populations of organisms, and for birds in particular,” the researchers write, “have been negative overall.”