In the early days of the pandemic, the Internet was rife with tales of nature reclaiming the world as humans were confined to their homes. Pumas took to the streets of downtown Santiago, Chile. Dolphins reappeared along the Italian coast. Jackals roamed city parks in Tel Aviv, Israel.

But it turns out this quieting of the human presence on the planet—the “anthropause” as scientists called it—didn’t just turn into a coming-out party for wildlife. Different types of animals reacted very differently, according to research published this month. Some animals proved relatively unfazed, while others shifted their behavior significantly as nearby human activity waxed and waned.

The results shed light on which kinds animals are most sensitive to human presence, insights that could inform conservation measures for endangered animals. “Understanding how wildlife respond to human activity in various contexts helps us develop effective conservation plans that have local and global impact,” said Cole Burton, an ecologist at the University of British Columbia (UBC) who worked on the study.

Ecosystem dynamics, including animal behavior, can be tricky to study in the wild, particularly on a global scale. There are so many variables at play it’s hard to tease out the effect of a single factor. Compound that with the differences from one place to another.

The global pandemic was a tragedy that killed an estimated 15 million people in the first two years. But it also presented an unusual opportunity for scientists interested in how the Anthropocene influences animals. The 2020 lockdowns served as a giant impromptu experiment. Places around the world suddenly changed in similar, stark ways as governments shuttered schools and businesses and ordered people to minimize their time away from home.  

“COVID-19 mobility restrictions gave researchers a truly unique opportunity to study how animals responded when the number of people sharing their landscape changed drastically over a relatively short period,” said Burton.

To capitalize on the moment, a group of scientists, including Burton, contacted researchers who were using motion-triggered cameras to monitor mammal movements both before and during the lockdowns. The observations covered everything from hulking polar bears to diminutive cottontail rabbits.  Most came from North America and Europe, though a smattering of studies originated in Latin America, Africa and Asia.

The researchers compiled information from 102 different projects. All told, the images from 5,400 cameras captured 163 species, adding up to more than 300,000 days worth of monitoring.

It turned out that not all animals acted the same when people became scarce. And those differences hinged not just on the type of animal, but also the surrounding landscape.

In forests, meadows and other less-developed areas, animals generally moved around less when humans were more active (like the other animals, human movements were gauged by how often they were captured by the cameras). The mammals’ appearance in photos fell by 6% as human activity rose, the scientists reported in Nature Ecology & Evolution.  The effect was greatest for carnivores such as wolverines, wolves and cougars.

The negative response in less developed places could be because animals there aren’t habituated to humans, or include more species with little tolerance for people. For large carnivors, compound that with a long history of humans eradicating them as pests or threats.

By contrast, many city-dwelling animals became more active as human presence rose, with an overall 25% increase in animal movement. But many of these urban animals shifted their busiest time to the night. That nocturnal shift could be the result of animals venturing out during times when there were fewer people around to pester them, the scientists surmise.

The findings suggest that particularly in wilder places, any human presence—even people hiking past a camera—could take a toll on wildlife. That might be particularly true for endangered species such as wolverines or wolves. So conservation efforts might need to consider creating no-go zones for humans to help wildlife in remote areas. “To give wild animals the space they need, we may consider setting aside protected areas or movement corridors free of human activity, or consider seasonal restrictions, like temporary closures of campsites or hiking trails during migratory or breeding seasons,” said UBC biologist Kaitlyn Gaynor, who worked on the study.

In a sense, it would be the flip side of the pandemic lockdowns. Then, people were discouraged from crowding together in urban areas. As a result, a growing number took to the woods and mountains. Now, some of those places might need lockdown of their own.

Burton, et. al. “Mammal responses to global changes in human activity vary by trophic group and landscape.” Nature Ecology & Evolution. March 18, 2024.

Image: From a timelapse video of camera trap photos of hikers and wildlife sharing a trail in Cathedral Provincial Park, British Columbia, Canada. ©Cole Burton, UBC WildCo.