Could Mountain Lions Help Solve Connecticut’s Deer Problem? | Connecticut Public Radio

Could Mountain Lions Help Solve Connecticut’s Deer Problem?

Jul 26, 2016

For humans, deer are actually the most dangerous wild mammal in North America.

Each year, thousands of deer are killed on Connecticut roads and highways. Those collisions can lead to costly insurance claims, injuries, and deaths -- which made scientists wonder what would happen to deer, and to us, if an elusive carnivore came back to the northeast: the mountain lion. 

Watching "Bambi," you'd never think it.

But Laura Prugh, a wildlife ecologist at the University of Washington said that to humans, deer are statistically the most dangerous wild mammal in North America.

"Everyone’s been in a car wreck with a deer out East -- or knows someone who has," said Prugh, who was involved in a crash as a teenage passenger in a car in Maryland. "We were driving to swim practice early in the morning and I was trying to sleep a little in the back seat and the driver hit a deer," she said.

Everyone in the car was fine, but Prugh said each year about 200 people die in 1.2 million crashes with deer across the U.S.

She estimates those car accidents are enough to cost Americans more than $1.5 billion in damages, which made her curious "to explore what would happen if cougars did return to the Eastern U.S.," she said.

Right now, all the major wildlife agencies say cougars are not here. The U.S. Fish and Wildlife Service says Eastern cougars are extinct.

Today, the only populations that can live and breed on their own are Western cougars and Florida panthers. But those cats appear to be wandering farther from home.

Photograph of cougar captured on a trail camera on January 18, 2010 in Clark County, Wisconsin. Wildlife officials believe this cougar may be the one that migrated over 1,000 miles before being struck by a car on a Connecticut highway.

In 2011, a cougar was hit by a car on a highway in Milford, Connecticut, and genetic testing revealed that cougar came all the way from South Dakota. Prugh and her colleagues believe that and other sightings in the Midwestern states raise the future possibility of a permanent population of Eastern cougars, which could impact deer populations.

To find out how, Prugh took lots of deer data, looking at birth rates, population density charts, and car impacts. Writing in the journal Conservation Letters, her team paired that up with cougar predation information from the Western U.S. and estimated that, over a 30-year period, cougars would reduce Eastern deer densities by 22 percent.

"Because they reduce deer density by 22 percent, then we projected that they would also decrease deer-vehicle collision rates by 22 percent," Prugh said. 

In other words, Prugh's team found cougars coming back to the region could actually save lives.

"As [an] idea it's great," said Morty Ortega, a wildlife ecologist at UConn. "Will it really work? It's very difficult for me to see it here in Connecticut," Ortega said. "I could probably see it a little bit more in Maine, for example."

Places where there are more continuous, and remote, forest landscapes. Ortega said Connecticut could potentially support mountain lions, but forest fragmentation means only a handful could live here at any one time -- and they'd have to adapt.

"This lion would have to learn how to cross highways -- how to move around and about," Ortega said. "And they will be moving within the backyards of a lot people."

Which Laura Prugh said could be pretty scary.

"Basically, a cougar is a 100-pound killing machine that has millions of years of evolutionary history as a specialized predator -- an obligate carnivore," she said. "They do specialize on deer, but they will, occasionally, attack people or pets."

Prugh said the fear of a cougar attack outpaces the reality, but in the U.S. and Canada, over more than a century, cougars have killed 21 people.

Bill Hyatt, a bureau chief at the state Department of Energy and Environmental Protection, said even if mountain lions did come back to Connecticut, they couldn't persist in the places where deer controls are most needed, like Fairfield county.

"Our overabundant deer populations tend to be in areas that are fragmented and highly residential - and those are areas that would be least likely to be able to effectively establish a large predator," he said.

Laura Prugh said the aim of her team's paper isn’t to necessarily inspire major cougar reintroduction efforts, "but if they do arrive of their own dispersal from the Midwest," she said, "that [cougars] would be more likely to succeed if the residents in the East are a little more welcoming of having them around."

In Connecticut, at least one group is ready to welcome mountain lions. For years, Cougars of the Valley has been on the lookout, sharing photos and setting up dozens of camera traps all over the state.

So far, they say they've had many false alarms and lots of great footage, but no shots yet of the elusive "ghost cat."