Photograph by Steve Winter, Nat Geo Image Collection
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A remote camera captures a radio-collared mountain lion in California's Griffith Park. The state's big cats live in habitats fragmented by major highways.

Photograph by Steve Winter, Nat Geo Image Collection

Roadkill rates fall dramatically as lockdown keeps drivers at home

As Americans stayed home in March and April, vehicle deaths declined up to 58 percent among large species like mountain lions, a new report says.

As humanity’s hubbub slows due to the coronavirus pandemic, some wildlife is benefiting: Roadkill has taken a precipitous drop in parts of the United States.

During the peak of the lockdowns in March and April, traffic on U.S. roads fell by as much as 73 percent. During that same period, fatal collisions with deer, elk, moose, bears, mountain lions, and other large wild animals fell by as much as 58 percent. Road deaths of dogs, sheep, and other domestic animals show a similar plunge.

"The longer it lasts, the more animals that would have died are not dying," says Fraser Shilling, co-director of the University of California, Davis Road Ecology Center and lead author of the report, which was released June 26.

If the current slowdown lingers and nationwide traffic remains on average 50 percent lower for a year, Shilling says, “then that’s 500 million vertebrates that aren’t killed on roads and highways. It's certainly not a small thing for wildlife.”

The study underscores the profound effects that roads and traffic can have on the functioning of ecosystem. “The very fabric of nature is threatened by this one [change]," Shilling adds.

Large predators play a crucial role in balancing ecosystems. The researchers took a close look at California’s mountain lions, which are in steep decline in many parts of the state due to habitat fragmentation by roadsleading to vehicle deaths and inbreeding among cut-off populations. Statistics from the 10 weeks before and after the lockdowns began show the number of mountain lions killed by cars fell by 58 percent—from around two deaths per week to less than one. (Read more about these ‘ghost cats.’)

“In this case, there’s a tiny, tiny silver lining of the coronavirus that has slowed cars down or has reduced the number of cars,” says Winston Vickers, a wildlife research veterinarian who directs the California Mountain Lion Project at the UC Davis Wildlife Health Center.

“That may reduce the mortality a little bit in this particular year,” he says. If the current traffic trend holds for a year, the report notes, 50 mountain lion deaths could be prevented in California.

Less roadkill is good for all

For the study, Shilling and colleagues analyzed roadkill data in California, Idaho, and Maine, states that each have comprehensive wildlife-collision reporting programs.

See Why the Mysterious Mountain Lion Is the 'Bigfoot' of Big Cats

In California, where the bulk of the reported large animal roadkill is deer, the number of deaths declined by 21 percent between early March and mid-April, from 8.4 to 6.6 per day. In Idaho, where the road-killed species are mostly deer and elk, deaths fell 38 percent, from 8.7 to 5.4 per day. And in Maine, where deer and moose top the list, fatal wildlife crashes dropped by 45 percent, from 15.2 to 8.4 animal deaths per day. (Read about how roadkill can inform science.)

These reductions in roadkill aren’t good only for wildlife: Across the country, an estimated 200 people die in car crashes with animals each year, according to the National Highway Traffic Safety Administration.

In a recent article in Nature, a group of scientists suggest calling the current curtailment of human activity the “anthropause.” It’s a stark reminder, they say, that many animals flourish when people aren’t around to encroach upon habitats. The abundance of wildlife in the exclusion zones around Chernobyl, Korea’s DMZ, and other abandoned places attests to this phenomenon.

Stubborn humans

U.S. traffic levels are already back to roughly half (or more) of what they were before the pandemic began, says Shilling. Although there could be further lockdowns in the future if coronavirus cases continue to surge as they’re doing now, when traffic eventually returns to normal, wildlife-people collisions will likely return to the same rate, he says.

The UC Davis study is consequential because it can help people appreciate the importance of making highways safer for wildlife, says Renee Seidler, a former road ecologist for the state of Idaho and now executive director of the Jackson Hole Wildlife Foundation in Wyoming.

Solutions for mitigating wildlife-people collisions include fencing off roads and building bridges or tunnels for animals to cross safely, Seidler says. (Read how wildlife bridges make animals safer.)

“It’s expensive, it’s a huge change on the landscape, it can be really stressful for the animals at some level,” she says. “But it may be one of the best solutions, because human nature is incredibly hard to change. It’s way easier to change wildlife behaviors.”