BALTIMORE — Other than the tiny population of panthers in Florida, cougars haven’t lived in the eastern United States for at least 70 years. There are occasional visitors from the west or south, but the eastern cougar (Felis concolor couguar) is probably extinct. For that reason, the U.S. Fish and Wildlife Service proposed removing it from the endangered species list earlier this summer.
But what if cougars returned to the eastern United States? Would that be a good thing? A team led by Sophie Gilbert of the University of Alaska, Fairbanks tried to figure that out from an economic standpoint. Gilbert presented the findings August 10 at the meeting of the Ecological Society of America.
The key is the big cats’ predation on deer. Deer are huge problems. The animals damage crops and gardens. They transmit diseases. And they get hit by cars, sometimes injuring or even killing people. Cougars eat deer, and if there were more cougars, vehicle collision rates might drop, the scientists figured. But there are downsides to having big carnivores around. They attack livestock, pets and even people. Are cougars a net positive or negative for society?
Gilbert and her colleagues used a computer model to simulate deer survival in the U.S. East and their effect on car crashes, and then added cougars (using data from where the cats still live in the West). The researchers included the fact that cars have been getting safer over time, and collisions with deer therefore are getting cheaper. And they considered where cougars would find better habitat (such as forests in the Appalachians) and thus kill more deer.
Over the coming decades, the team calculated, the presence of cougars would result in a 22 percent decline in deer-vehicle collisions. That would result in tens of thousands of fewer human injuries, hundreds fewer human deaths and billions of dollars in savings, over half of which would go to insurance companies. “A cougar might lower your insurance premium,” Gilbert quipped.
To determine whether the presence of cougars is a net benefit to society if they were present in the east, Gilbert and her team then considered other factors beyond vehicle collisions, such as a reduction in the damage done to agriculture and landscaping by deer, and the potential costs of cougars attacking livestock and humans. They calculated that the benefits of restored cougar populations outweighed costs by 30 to 1. “There will be a benefit” if cougars return to the East Coast, Gilbert said.
But there were plenty of factors the team couldn’t include, such as hunters losing the opportunity to go after deer and gaining the chance to hunt the big cats. They didn’t consider the effect of reduced numbers of deer on the transmission of diseases, such as Lyme disease. They also couldn’t find any data on the costs of cougar attacks on pets. “Obviously, it’s very hard on people when their pet gets eaten by a cougar,” Gilbert noted.
And that’s where any cougar reintroduction project may fail, in my view. Even if there is a monetary benefit from reintroducing cougars to the U.S. East, the public might have a difficult time seeing that, especially if most of the benefit goes to insurance companies. “You are far more likely to be killed by a deer than a shark or a cougar,” Gilbert noted. But one dead human — or a few dead pets — might be enough to sink any reintroduction project.
That said, I’d love to see someone give it a try.
Editor’s note: This story was updated August 14, 2015, to amend the figures related to reductions in injuries and deaths and the cost savings that would come from fewer deer-car collisions.