A white-tailed eagle soared in the crisp winter air. The majestic bird was hunting for fish in the giant cooling pond whose waters doused the inferno that followed the world’s worst nuclear accident, at the Chernobyl nuclear power station in Ukraine in 1986. The water in the pond was radioactive. The fish in the pond – including the giant male catfish that tour guides had named Gosha -- were radioactive. And so, presumably, was the eagle.

It doesn’t seem to matter. Wildlife is blooming in the exclusion zone stretching for 30 kilometres round the site of the accident. Top predators like eagles and wolves seem to be doing best of all.

Wolves prowl around the zone in record numbers, says Marina Shkvyria, a wolf expert at the Institute of Zoology in Kiev. She has definitely logged 40-50 wolves in the Ukrainian half of the zone, congregated round seven dens established since the accident. That is a conservative estimate based on counting animal tracks in winter snow during brief helicopter surveys.

Ecological nightmare or nirvana? Shkvyria has no doubts. “The exclusion zone for me is a window into the past of Europe, when bears and wolves were the bosses here,” she told me. It might also be a gateway to the future of nature on our crowded planet. “Here we learn to understand the realities of co-existence with nature and society.”

Visitors expecting a blasted wasteland, or animals that glow in the dark, have a surprise in store in the Chernobyl exclusion zone. Strutting round the forests of a territory deemed too dangerous for humans to linger are extremely healthy looking wild boar, grey wolves, Przewalski horses, hares, foxes, moose and bears. The zone seems in the pink of health. Certainly, there is no better place for researchers to unravel just what damage radiation does and does not do to nature.

Other ecologists are equally ecstatic at the rewilding of this part of northern Ukraine. Sergey Gaschak, scientific director of the Ukraine government’s Chernobyl Radioecology Centre, has been watching the upsurge since arriving to help with the aftermath of the disaster in 1986. “We can’t prove it yet. But I think there may be around 60-90 lynx and maybe even more wolves, just among the adults. Wolves are everywhere. Bears have been here permanently for over a decade. We have seen their cubs.”

The exodus of people has resulted in “a reinstatement of nature unique in Europe,” he says. The exclusion zone has created “endless opportunities for animals and plants to prosper”. If radioactivity keeps humans away, then it can only be good for wildlife.

Gaschak took me to Buryakovka, one of the 113 villages evacuated after the accident. It was a few miles southwest of the stricken reactor and near to the site where the Ukraine government is building a store for the most radioactive waste left in the reactor.

We drove down a long, potholed and overgrown lane. At the end were half a dozen wrecked houses, all that remained of the village. This area was beneath one of the most persistent fallout plumes during the fire, he said. Radioactivity here was 50 times higher than in some other parts of the exclusion zone. But wildlife had no problem.

Among the village buildings he had set up two cameras, whose shutters were tripped by passing animals. He took the memory card out of one and plugged it into his laptop. Up popped a procession of Przewalski horses – part of a herd released into the zone in the 1990s – plus a fox, a moose and several red deer.

The other camera had recorded much more: wild boar, pine martens, dogs, wolves, foxes, racoons, badgers and a couple of rutting male red deer. “I’ve seen lynx in this village, too,” he said. “Once I saw six within a few minutes.”

Gaschak’s checklist of wildlife in the exclusion zone included 59 species of mammals, including beavers and otters; and 178 species of breeding birds, including nine types of woodpeckers, four eagle species and eight owls. Few places seemed too radioactive, he said. He had even found starlings, pigeons and swallows nesting inside the sarcophagus built round the remains of the reactor.

Across the nearby border, in Belarus, they have found many animals congregating in abandoned villages and farm buildings. Wolf densities are seven times higher than in nearby non-radioactive reserves.

The government of Belarus long ago turned its section of the exclusion zone into the Polesye State Radioecological Reserve. In 2016, to coincide with the 30th anniversary of the accident, Ukraine announced that it was going to do the same.

I’m not sure how compatible that is with the planned radioactive waste dumps that is also wants to put here. But the World Bank’s Global Environment Facility has suggested that the two countries amalgamate the two into a cross-border reserve that would cover 2000 square miles.

Some say we should not take this apparent radioactive wildlife renaissance at face value. Before visiting the zone, I had gone to a museum in the Ukrainian capital Kiev that is dedicated to the Chernobyl accident. It told a darker story.

It highlighted the Red Forest, an area of Scots pine trees close to the reactor site where all the pine needles turned the colour of rust and died. Later, they were bulldozed and buried. The lingering fallout makes the forest still “one of the most contaminated areas in the world today.” Certainly, the readings on my Geiger counter soared as we drove swiftly through the Red Forest.

The museum’s displays also claimed ominously that “new bacteria and viruses” had been discovered in the exclusion zone, along with “300 abnormal animals… Deformities went from 8 percent to 20 percent.” It gave space to a large lurid picture of mutant twin pigs – one head and two bodies. They may or may not have anything to do with radiation or the accident. It didn’t say.

Maybe some of this dystopian take is for tourists, and to feed anger among Ukrainians about the radioactive mess left behind by the Soviet Union’s nuclear apparatchiks. But a number of academic studies do show apparent ill-effects of radiation on nature in the zone.

Vasyl Yoschenko is a forest ecologist who has worked in the zone for 25 years. He says that the young Scots pine trees that have grown in the exclusion zone since the accident are often mutant. The normal tall straight trees have been replaced by more bush-like trees, with many branches rather than a single trunk.

Canadian ecologist Timothy Mousseau and his Danish co-researcher Anders Moller have reported that the more radioactive places in the zone suffer a range of less visible symptoms. They have found fewer bacteria in birds’ feathers, damaged DNA in mice, declines in insect populations such as bumble bees, and smaller craniums and reduced biodiversity among birds.

This is a worrying counter-narrative to the stories of nature blossoming. So who is right? Or could both be?

I attended a workshop of ecologists who have been doing research inside the exclusion zone. They tended to optimism, and questioned some of the findings from Mousseau and Moller, who they rather disparagingly referred to as “M&M”.

Their own studies found plenty of bumble bees, even in the more contaminated areas. They also questioned whether Mousseau and Moller were seeing greater DNA damage. The pair had no good baseline data from before the accident, and there was growing evidence of widespread DNA damage in normal populations of many species. Maybe what they measured was normal.

Gaschak, who had helped organise the workshop, told me some of the findings may be real but unconnected to radiation. For instance, Moller and Mousseau reported that pied flycatchers much preferred nesting in boxes pinned to trees in areas with low radioactivity, and shunned those with higher levels. It looked like a clear effect of radiation. But Gaschak claimed the radioactivity was irrelevant. Most of the high radiation areas in the study were in the Red Forest.

He did not contest that the birds had largely disappeared from the Red Forest. But after the Scots pine trees died following the accident, the area was replanted with birch forest. Pied flycatchers are well known not to enjoy birch woodland. “Isn’t that an equally likely explanation for their disappearance, rather than radiation?” he asked.

There seems to be a stand-off between two factions in this decade that may owe more to politics among the scientists than to science itself. In my journeys round the world’s nuclear badlands, I frequently found this polarization.

Researchers either look for the good or the bad, depending on their general attitude to all things nuclear. They also hunt in packs. One group finds nature blooming; the other finds only genetic damage. This tribalism is pervasive. Most scientists have reputations to defend, and friends to support.

To try and break down barriers, a conference on the impacts of radiation on ecosystems held in Miami in 2015 was flagged up in advance as a “consensus symposium”. But there was no consensus. “There is a feeling of divergence rather than convergence in current opinion,” its organisers later concluded.

There is clearly truth on both sides. Scientists are not liars. It would be foolish to claim radiation has no impact. It may indeed be causing subtle genetic changes. It is also possible, as pessimists fear, that such changes could accumulate in the gene pool of some species, eventually escalating to produce big ecological impacts a few generations down the line.

But though wildlife probably doesn’t enjoy radiation, it often doesn’t much like people either.

In the exclusion zone, animals generally keep away from the areas where people go, such as round the power plant and in Chernobyl town, where many of those working to make the plant safe stay. But elsewhere, in the empty forests and wetlands that cover two-thirds of the zone and harbour most of the radioactivity, nature mostly thrives.

The bottom line seems to be that for many species, the radioactive threat is more than compensated for by the freedom from humans. Biodiversity in the Chernobyl exclusion zone is greater than elsewhere in Ukraine – greater even than in the country’s protected areas. It appears to be growing. For Chernobyl’s wildlife, if may sometimes be a short life; but in the absence of humans it is often a merry one.