Cows Left Behind in Chernobyl – Now the Herd Is Growing

When reactor four at the Chernobyl Nuclear Power Plant melted down on April 26, 1986, and spread large amounts of radioactive waste over parts of Ukraine and Belarus, people in the area were evacuated.

Around the nuclear power plant, authorities created a so-called exclusion zone. Within a 30-kilometer radius around the power plant – an area the size of the Danish island of Funen – people were only allowed for short periods at a time with a special permit.

In Ukraine and Belarus, more than 100,000 people were evacuated and rehoused.

However, some people defied the authorities. Just a few months after being evacuated, they snuck through the forests, crawled under fences, and bribed guards at checkpoints to return to their homes in the exclusion zone.

In Ukrainian, they are called Samosely, which means something like "self-settlers." It was primarily elderly people living on small farms in villages who returned. They resumed their small-scale farming and tended to their animals, but over time most of them have died of old age – and today, only a very few remain.

In one of the small villages, Lubyanka, the last resident, Olga, died in 2016, leaving behind a small herd of dairy cows. One might think the cows would starve and die with no one left to care for them. But that is not at all what happened.

This is shown by new research led by postdoctoral researcher Anastasiia Zymaroieva from the Department of Biology at Aarhus University.

"The cows still spend the night in the barns, but they roam around the area to graze. They manage completely without human help and have formed a herd with a clear hierarchy. There is even a bull that leads and protects the herd," she explains.

Together with a number of colleagues from Ukraine, she has followed the herd for several years, providing a unique insight into what happens when domesticated animals are released into the wild. The researcher has followed the cows from a distance to document how they manage. And they are doing remarkably well, she says.

“They are thriving. They get plenty to eat and look healthy and fit. The herd has even grown from seven to 17 individuals.”

In the vast area around Chernobyl, nature is thriving without human interference.

The wolf population is seven times higher than in similar nature reserves; lynx and brown bears, which had been extinct in the area for more than 100 years, have returned; the wild boar population is growing, and rare birds of prey as well as black storks nest undisturbed in the forests.

And this is despite the high level of radiation.

Animals and plants are indeed affected by the pollution. Close to the nuclear power plant, dead trees and plants decompose more slowly because insects and fungi struggle to live there. Small animals like barn swallows and mice exhibit a range of rare mutations. Birds have smaller brains and crooked tail feathers, and more albinos hatch. Mice have lower fertility and suffer from cataracts more often than mice elsewhere.

Yet, the populations are thriving – better than in areas with human disturbances such as roads, cities, and cultivated land. And the same goes for the dairy cows, Anastasiia Zymaroieva explains.

"Even though they are domesticated animals, they adapted very quickly. In fact, they have become afraid of humans. They see us as predators and no longer dare to approach people."

Despite the cows faring well since their owner's death, they have also been affected by the war in Ukraine, Anastasiia Zymaroieva explains.

"When Russia attacked us in February 2022, troops moved into the area around Chernobyl on their way to Kyiv. We don't know exactly what happened, but several cows had disappeared by the time the troops withdrew.”

“We think they might have killed them for fun. They were roaming around the area and were probably bored. They completely destroyed our office, stole cars and vans. They even planted landmines in one of our cars," she says.

After just a month, the Russians withdrew from the Chernobyl area as the capture of Kyiv failed. Anastasiia Zymaroieva and her colleagues were able to return to the office and check on the cows.

"They are doing well again, and the herd is growing. However, the war shows how quickly human influence can harm nature. It thrives when we leave it alone," she says.

Anastasiia Zymaroieva’s research is not only relevant to Ukraine. Because the exclusion zone is a very special place, it provides an opportunity to study what happens when nature is left entirely in peace.

And her research shows that the animals will manage.

"The results show that the animals and nature will be just fine. It proves that rewilding actually works. We shouldn't interfere and feed the animals. They don't need us," she says.

Even domesticated animals that have lived closely alongside humans and are used to being fed can adapt fairly quickly – and that offers hope for the future, she says.

"Which animal species you choose for rewilding isn't important. Just look at how local animals that have been bred by humans for a thousand years quickly adapt. You don't need an ancient, fancy breed. Just use what you have," she says, adding:

“Of course, some animals will die. Weak individuals die in nature. That's just how it is. It's the way of nature. If we want to bring more nature back, we have to leave it alone. This clearly demonstrates that.”