Wild animals have free range around northern Ukraine’s Chernobyl nuclear plant, the site of the world’s worst nuclear accident, which spread radiation throughout the region in 1986.

Studies have hinted that significant populations of European gray wolves and other large creatures live in the Chernobyl Exclusion Zone, the roughly Rhode Island-sized, 1,000-square-mile section from which people were evacuated and can no longer live.

While clear of humans, animals are not free from radiation and its health effects, an active and at times controversial area of research. Many questions remain about the extent to which radiation causes mutations in various species, and whether these could be spread outside the zone. (Related: Animals Rule Chernobyl Three Decades After Nuclear Disaster)

Epic Trek

In a recent experiment, researchers tracked 13 wolves using collars that could measure radiation, and found that, not unexpectedly, the animals encountered more radiation when they traveled through more contaminated areas. But one observation in the study, published in the European Journal of Wildlife Research, stuck out: A collared young male took a 250-mile-long trek out of the region, first heading east into Belarus, then into Ukraine, and eventually into Russia.

This is the first recorded long-distance wolf migration from within the Chernobyl Exclusion Zone to its surroundings, says study leader Jim Beasley, a wildlife ecologist at the University of Georgia in the United States.

Young male wolves are known to travel long distances in search of mates, so that in itself isn’t shocking, Beasley says. However, it provides further evidence that there are major populations of the animals in the Chernobyl region, Beasley says.

“We know the wolf population in the Chernobyl Exclusion Zone is high,” says first author Michael Byrne, who studies animal movement and ecology at the University of Missouri. “You’d expect that as a population of any animal, once it gets to a certain level, can only hold so many—so young animals will disperse.”

“It came time for him to go out in the world and get a job,” Byrne jokes. (See photos taken on illegal visits to Chernobyl’s dead zone.)

This epic trek also raises the question of whether or not the animals could spread mutations to wolf populations outside the area, he adds.

Mutations Spreading?

Studies in other animals—mostly smaller ones like birds, rodents, and insects—show that Chernobyl radiation can cause mutations and ill health effects, says Tim Mousseau, a biologist at the University of South Carolina who was not involved in the recent study.

And work done in creatures such as barn swallows and voles suggests these mutations may be transferred to the next generation, he says. These smaller animals also have the potential to spread radioactive contaminants to the environment through their movements, Mousseau notes.

A JOURNEY INSIDE CHERNOBYL’S EXCLUSION ZONE

But so far, the picture is less clear in wolves, he says. “It’s certainly plausible,” he says, though there are not large populations of wolves immediately surrounding Chernobyl to spread these mutations to. In other smaller animals in the area, exposure to radiation has been associated with tumors, cataracts, smaller brains, and certain developmental abnormalities.

Anders Møller, a scientist at the University of Paris-Sud, argues that since most mutations are harmful, it’s unlikely that a wolf capable of moving this far would be heavily impacted by radiation. Furthermore, he contests the idea that wolves are “thriving” in Chernobyl, as some scientists have suggested, saying that wolves are also doing well in other areas of Europe.

Radiation Vibe

Instead, Møller’s work shows that “hot” areas with high levels of radiation have low populations of wildlife, and it follows that animals that linger in these regions may sustain genetic damage. The Chernobyl landscape is quite varied; much of it remains pristine, while pockets still harbor high levels of radiation. (Read about other places where animals thrive without people.)

“I can go out blindfolded to a random location in Chernobyl and I’d be able to tell you the level of background radiation based on the amount of birds in the area,” and thus the amount of audible birdsong, Møller says.

One debate concerns the degree to which the Chernobyl area serves as a source or “sink” for surrounding animal populations. Byrne and colleagues have a hunch that the region could be a population source for wolves, and if so, that would mean any radiation-caused genetic damage could spread to other wolf populations.

The authors stress that more work needs to be done to answer questions raised in the paper.