Large carnivores lower deer-vehicle collisions.
What is the most dangerous mammal to humans in North America?
The answer might surprise you.
It is the timid, graceful white-tailed deer.
Deer are responsible for over 1 million vehicle collisions, leading to more than 200 deaths, in the US each year.
North American deer numbers were once kept in check by large carnivores such as cougars, a.k.a. mountain lions. But state-sponsored bounty hunts aimed at protecting humans and livestock completely wiped them out in Midwestern and eastern states by the early 1900s, allowing deer populations to flourish.
Writing in the journal Conservation Letters, researchers argue that bringing cougars back to their historic range would lead to prevention of “21,400 human injuries, 155 fatalities, and $2.13 billion in avoided costs within 30 years of establishment.”
Their population models revealed that a single cougar would kill roughly 259 deer over its average 6-year lifespan, preventing 8 collisions and saving nearly $40,000 in associated costs.
Although cougars also pose a threat to humans, the researchers estimated that on average they would lead to less than one death per year, which is far outweighed by the number of lives saved.
"Carnivores are so controversial and there's a lot of fear, anxiety and resistance when they are reintroduced or recolonize an area,” said the study’s senior author, University of Washington's Laura Prugh, in a statement.
"The important take-home is that there can be very tangible benefits to having large carnivores around — economic and social benefits, not just ecological benefits."
The researchers compared their modeling projections with a real-life test case in South Dakota, where a viable cougar population currently lives. Since their repopulation of the region in the 1990s, deer-vehicle collision rates have dropped dramatically, providing further evidence that cougar reintroductions elsewhere could have positive effects.
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