With people sheltering in place worldwide due to the coronavirus pandemic, animals have been ranging more freely in areas they’re not normally seen. Wild goats are roaming a Welsh town. Fin whales are coming closer to shore near the shuttered port of Marseille, France. Wild boars are more boldly wandering through cities in Spain, Turkey, and Israel.
While some supposed sightings that went viral on social media, such as dolphins in Venice and lions in Russia, turned out to be fake, some animals are indeed benefitting from the absence of humans sharing their spaces.
Sea turtles, for example, are having an easier time nesting on once-crowded beaches in places like Thailand and Florida. Flamingo numbers in lagoons of western Albania have grown by a third in the absence of tourism and boating activity. Even so, these changes in animal behavior are likely to revert once people go back to their usual activities.
But there are other places where shifts in human habitation are more permanent—where accidents or warfare have forced people out for the foreseeable future. Among them: the exclusion zones around the Chernobyl and Fukushima Daiichi nuclear plants, the sites of the two worst nuclear accidents in history; and the Demilitarized Zone between North and South Korea.
Research on these areas, including a recent study on Fukushima, shows that the mere presence of humans may be the most important factor limiting the local abundance of wildlife. Studies suggest that animals have multiplied in regions now abandoned by humans, despite impacts such as nuclear fallout that have driven people out. That’s not to say radiation doesn’t harm animals—but the extent of such effects, particularly low-dose exposures, remains controversial, and may pale in comparison to impacts to humans. One of the most pernicious human effects of radiation, cancer, does not always manifest in wild animals because some don’t live long enough for the mutations to accumulate.
Now that the pandemic has people “holed up in houses, nature has issued a sigh of relief,” says Tom Hinton, a radioecologist at Fukushima University and co-author on the new study that looks at the long-term effect for animals when people leave a densely inhabited area.
Hinton isn’t suggesting that people abandon populated centers or stay inside all the time to benefit wildlife. But the resurgence of animals when humans are gone does show the importance of setting aside large, contiguous habitats for wildlife—and enforcing a certain level of non-interference, he says.
On March 11, 2011, a massive earthquake and tsunami triggered the world’s second-worst nuclear accident, after Chernobyl. At the Fukushima Daiichi plant in northeastern Japan, power failure caused by inundation allowed three reactors to melt down, leading to fallout seen through the surrounding coastline. In all, about 160,000 people fled a 440-square-mile area (nearly the size of New York City) surrounding the plant.
To look at the relative influence of radiation and human abandonment on wildlife in the vicinity of Fukushima, lead researcher Jim Beasley, Hinton, and others conducted camera trap surveys at 120 sites near the former nuclear plant over the course of two two-month periods between 2016 and 2017.
They selected sites in three zones: where people are completely excluded for the foreseeable future, where people were first excluded but have now returned to a small degree, and populated areas with similar habitat.
The researchers found the highest numbers of some species—including wild boars, Japanese macaques, and raccoon dogs—in areas where humans are not allowed to go. Generally, the most important factors for predicting the presence of animals was habitat type and human abandonment, but not radiation levels.
“There is an irony that these contaminated landscapes are able to support viable populations,” says Beasley, a wildlife ecologist at the University of Georgia in the United States. The study he and Hinton led was published in Frontiers in Ecology and the Environment.
Though large, unspoiled wildlife reserves would be better for wildlife, the findings show that animals can still abound even in the face of radiation. “Radiation dose had essentially no effect on where these wildlife were most abundant,” Beasley says.
In 1986, a reactor at the Chernobyl Nuclear Power Plant in Pripyat, Ukraine, exploded during a botched test, leading to a massive fire and peppering the nearby landscape with radiation-emitting nucleotides. This led to the creation of a large exclusion zone in modern-day Ukraine and Belarus, about the size of Rhode Island. More than a hundred thousand people were forced out of the area and were never allowed to return.
Research over the last couple decades has shown that the Chernobyl Exclusion Zone has significant populations of many types of animals, on par with nearby nature reserves in some cases. Research findings differ on just how much the radiation in the area affects the creatures there.
Impaired fertility and elevated mutation rates have been seen in birds and rodents, for example, says Tim Mousseau, a biologist at the University of South Carolina. Work in voles shows these mutations can be passed down from parents to offspring.
Anders Møller, a scientist at the University of Paris-Sud, says that while Chernobyl might have an “increase in certain birds or certain mammals, we also know they are not in good shape.”
Radioactive materials, specifically cesium-137, an element found at both Chernobyl and Fukushima, cause damage to bodily tissues and even DNA by emitting radiation that can travel dozens of feet.
Regardless, in the absence of human presence and hunting, many species that were previously absent or scarce—including gray wolves, raccoon dogs, and badgers—now live here in significant numbers.
Multiple lines of evidence “support the idea that there are abundant populations of mid- to large-sized mammals in Chernobyl Exclusion Zone,” Beasley says. (Learn more: Could Chernobyl wolves be spreading mutations?)
DMZ of Korea
The Korean Peninsula’s Demilitarized Zone, also known as the DMZ, offers yet another example of a place where wildlife multiply in the absence of humans.
Following the Korean War, North and South Korea established a no-man’s-land between the two countries known as the DMZ. Today it’s still littered with former villages, military hardware, remains of soldiers, and landmines.
A tense semi-peace has reigned for nearly 70 years at this 2.5-mile-wide boundary between the countries. This has allowed rare animals like endangered red-crowned cranes, Asiatic black bears, Korean foxes, and goat-like amur gorals to thrive. (See pictures of wildlife in the DMZ.)
The DMZ itself is recognized by conservationists as one of the most important places for wildlife in East Asia.
As for takeaways from this research and the current pandemic, Hinton says, “it kind of boils down to: We’ve identified the problem, and it’s us.”
“I hope [this] can motivate people to realize we only have one Earth, and maybe we shouldn’t mess it up.”