As states locked down to slow the spread of the coronavirus, the nation’s roads became less deadly for wild animals, most likely sparing millions of them from becoming roadkill, according to a new report.
The number of wild animals killed per day in Maine during the first four weeks of the state’s shutdown was down by as much as 45 percent compared with the four weeks before its stay-at-home order went into effect, researchers at the University of California, Davis, found.
Compared with the four weeks before locking down, roadkill incidents dropped by 38 percent in Idaho and 21 percent in California during the first four weeks of each state’s shutdown. According to the report, released on June 24 by the U.C. Davis Road Ecology Center, the findings from Idaho, Maine and California show the impact of fewer cars on the road in three states with varying ecosystems and infrastructure.
The idea that fewer animals would be killed on roads as fewer vehicles traveled on them might seem obvious, but the stay-at-home orders provided a unique opportunity to confirm the relationship between traffic and wildlife across the continent, said Fraser Shilling, a director of the Road Ecology Center.
“We haven’t had an experiment of this scale,” Dr. Shilling said. Around one million wild animals are killed every day on U.S. roads and highways, meaning tens of millions were probably saved because of the shutdowns over recent months, he said.
A majority of known roadkill incidents involve large mammals like deer or elk because it’s unlikely that the death of a small reptile or amphibian would be reported, according to Dr. Shilling, who emphasized that those smaller creatures — like salamanders — have ecological importance, too.
Road mortality is a significant threat to many wildlife populations, said Erik Blomberg, an associate professor of wildlife ecology at the University of Maine. Both experts pointed to the Florida panther as an example of the devastating impact that vehicle traffic can have on species or local populations. Mountain lions in California appear to have especially benefited from the shutdown: There were 58 percent fewer deaths by vehicle in the 10 weeks after the stay-at-home orders compared with the 10 weeks before, according to the report.
The decrease in deaths will most likely have a net positive benefit beyond just the animals whose lives were spared, Professor Blomberg said. Those animals are now able to cross roads to reproduce with other populations, contributing to the sort of gene flow that makes a species more resilient, he said.
But there’s no need to worry that the collaterally spared animals will lead to a surplus of wildlife crowding roads, Dr. Shilling said. Rather, the lockdowns provide a temporary reprieve from the damaging loss of wildlife to vehicle traffic during normal times.
The impact of the shutdowns on animal populations has its limits, Professor Blomberg said, noting that the drop in deaths could easily be a small, “one time only” blip. Dr. Shilling said it was likely that wildlife deaths would increase as vehicle traffic picked up again.
While the decrease in roadkill incidents is undoubtedly good news for the animals, it also represents a decline in collisions that often cause human deaths as well, according to Professor Blomberg.
The sparing of human and animal lives amid the pandemic is the “silver lining of a terrible situation,” he said.