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February 02, 2023

Reintroducing cougars to Pennsylvania would better control its deer population, some scientists say

The game commission wants to leave that job in the hands of the hunters. But studies suggest the return of mountain lions would reduce traffic accidents and deaths

Wildlife Cougars
Cougars Pennsylvania Nicky Pe/Pexels

Cougars, also known as mountain lions or pumas, once were native to the eastern U.S. Some biologists thinks it's time to bring them back to help manage deer populations.

Thousands of deer scamper onto American streets each year, colliding with startled drivers and causing roughly 200 deaths. States have tried all kinds of strategies to bring down the number of crashes, from capturing and sterilizing deer to encouraging hunters to go open season.

Some biologists have an unusual solution: cougars.

Cougars — also called mountain lions or pumas — are uniquely suited to hunt and kill deer, who not only cause traffic accidents but overgraze to the point of endangering native species and eliminating habitats for smaller animals. The big cats are risk-adverse, solo hunters with impressively high kill rates. 

According to a 2016 study, a single cougar can kill up to 259 deer over the course of its lifetime, single-handedly preventing eight crashes and nearly $40,000 in damages. All told, they could eliminate 708,600 collisions and $2.13 billion in damages over 30 years.

"Cougars really are deer specialists," said Laura Prugh, an author on the study. "Deer pose relatively less risk to them compared to larger animals. But then it's a really nice-sized meal as well, so it's an efficient package of meat that can feed them for about a week, as opposed to hunting smaller prey like beavers or rabbits."

According to Prugh, cougars also could help slow the spread of Lyme's disease by taking out diseased deer and save casual gardens and crops from overgrazing. With less deer roaming forests, she said, plant and bird biodiversity might improve, too.

Except there's one big problem, at least for East Coasters: cougars don't really live here. The big cats largely disappeared from the eastern U.S. roughly a century ago. In 2011, the U.S. Fish and Wildlife Service formally declared the eastern cougar extinct, but said the subspecies had probably been stamped out in the 1930s. Cougars had long been targeted by early American settlers paranoid over livestock losses, the agency found, with some states going so far as to offer bounties for dead cougars. 

For many decades, cougars confined themselves to prowling the wooded and mountainous areas of the western U.S. But in recent years, the animals have been moving east. Wildlife experts have noted, with astonishment, cougar populations in midwestern regions like North Dakota and Nebraska. Since 2004, when scientists found a dead cougar on train tracks in northern Oklahoma, they have recovered more than 100 additional cougar bodies east of the Rocky Mountains. At least one made it to Chicago; another wound up in Connecticut.

Given the cougar's effectiveness as a deer population control, some biologists think this eastern push is a good thing — one that should even be encouraged or helped along. In an October study, researchers identified several regions along the East Coast that could be suitable habitats, including a section of Pennsylvania north of Du Bois and northeast of Williamsport.

"People do hunt deer, and we are hiring sharpshooters and it hasn't brought their populations down the way that a healthy population of cougars would be able to do," Prugh said. "Cougars are hunting deer year-round. They're able to hunt deer in suburban areas where it's not safe to hunt. They also instill a fear. Predators have an effect on their prey without actually killing them."

But they'd need the cooperation of the Pennsylvania Game Commission and, for now, that's a non-starter. The commission's furbearer biologist Thomas Keller said the PGC would "likely not be supportive of mountain lion reintroduction," pointing to the dangers posed to hikers, pets and other wildlife.

"Although I understand why and what (proponents are) trying to say, I do not agree that this would be the case in Pennsylvania without having other major negative implications," he said in an email. "Even if the habitat model is showing suitability, it's really so many other things that need to be considered such as impacts to other species, impacts to humans, social acceptance and future management."

As biologists are quick to stress, cougars rarely attack humans. A 100-year survey of cougar attacks in the U.S. and Canada found only 10 deaths and 48 injuries. But they are less shy of pets and livestock, and they don't necessarily stay in the woods, either. Most of the recent cougar sightings east of the Rocky Mountains were confirmed due to some kind of crash with a train or vehicle — and as any Angeleno could tell you, some of them even reside in cities.

"In one sense you would return a missing ecological community member back to the forest system," Keller said. "But there is certainly major costs to that return. When we consider apex predators currently we have the black bear, and then to a lesser degree the coyote. How would mountain lions impact black bears? How would mountain lions impact the entire trophic scale underneath them? Are Pennsylvanians OK with these changes? Are hunters OK with fewer deer?"

If cougar reintroduction were to become a serious consideration, the game commission would first need to conduct a feasibility assessment, a "long and careful process," in Keller's estimation, that ends with a recommendation for or against reintroducing a species. 

Last year, the commission recommended reintroducing the pine marten, a much smaller and cuter omnivore once native to Pennsylvania. But even that little guy isn't prowling the Poconos yet. The commission still needs to submit a management plan, due this June, gain approval and mount a public education campaign before the first marten steps on Pennsylvania soil.

If the pine marten requires this much paperwork, one can imagine where that leaves cougars. For now, the state will stick with its current deer management plan, which leans heavily on hunting. 

Cougars in Pennsylvania may still be a pipe dream in 2023, but who knows? Maybe someday, one of those fake cougar sightings will turn out to be true.

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