It’s the site of the greatest nuclear disaster of all time, and its high levels of radioactivity have made it an unsafe area for humans to go in the decades since the disaster happened — but a surprising new study has found that wildlife has been doing quite well.

The exclusion zone that was placed around the area where a Soviet nuclear power plant melted down in what is now Ukraine is still in place, keeping humans from visiting the eerie ghost town where radiation levels remain very high, according to a Slashgear report.

But there’s nothing that can be done to keep wildlife out, and researchers were surprised to find in a recent study that they are actually doing quite well in the Chernobyl zone, based on data published in the Current Biology journal.

The Chernobyl zone spans about 4,200 square kilometers, which are all about bereft of human life. But wildlife is packing the region at levels scientists din’t expect, particularly wolves. Scientists have noted there are seven times as many of them in the zone compared to nearby parks based on aerial observations of the exclusion zone.

It appears that the levels of wildlife are at the very least back to pre-meltdown levels.

Radiation remains at dangerous levels, but perhaps not as dangerous as before, and the wildlife seems to handle it better than they would have in the past. Not only wolves are being seen in greater numbers, but also deer, wild boar, and elk compared to just 10 years ago.

The Chernobyl disaster happened all the way back in 1986, a few years before the Cold War ended. It happened at the Chernobyl Nuclear Power Plant in what was then part of the Soviet Union but is now within the boundaries of Ukraine.

It was the worst nuclear power plant accident in history, both in terms of cost and in terms of deaths. It is the only level 7 event — the maximum nuclear accident classification — other than the 2011 Fukushima Daiichi nuclear disaster. It took an estimated 500,000 workers and 18 billion rubles to contain the disaster, and 31 people died during the actual accident and untold numbers from the large rise in cancers likely due to the radiation fallout.

The accident happened when during an experiment that was a massive explosion that blew open the reactor and resulted in a meltdown that released huge quantities of radiation into the atmosphere, a plume so large that other countries detected it and confronted the secretive Soviets about it.

After the accident, authorities set up the Chernobyl exclusion zone, which originally extended 30 kilometers in all directions. Everyone evacuated except for about 300 residents who wouldn’t leave their homes no matter what the risk. Today, it is an eerie ghost town, with the towers of the Chernobyl power plant still towering over the overgrown buildings surrounding it. Much of the area has been swallowed up by the forest, and wildlife has been ale to run amok with humans gone.

Work is still being conducted on rebuilding the sarcophagus that encloses the ruptured reactor in order to prevent continued radiation release. Radiation levels are so high in the area that workers can only work five hours per day for a month before getting 15 days of rest. It is estimated that it will be about 20,000 years before it is safe for human habitation.