If you've hiked a lot in the western US, there's a decent chance you've been close to a cougar but just don't know it. That's because they are incredibly secretive, and have one of the lowest attack and fatality rates on humans of any big cat (although they're very effective at preying on deer and other wild mammals, as well as livestock and pets in some instances).
They are also relatively tolerant of human activity and disturbance— look no farther than the populations living in California's coastal mountains above Santa Cruz. There, researchers found the big cats avoid humans, especially when choosing a den site or seeking a mate, but still managed to feed, move, and reproduce successfully in relatively close proximity to human populations.
But the eastern US has been devoid of cougars for many decades, with the exception of the Florida Panther (a smaller and endangered sub-species of cougar occurring only in certain parts of Florida). While cougars are slowly re-colonizing patches of suitable habitat in the Midwest, human densities are much higher in the east. Is it even possible for cougars to live in such a human-modified landscape? Can they get there on their own, if so? And how might they impact humans, positively and negatively, if they get there?
A new research paper out this week by Mark Elbroch of Panthera, is making the case for returning cougars to viable habitat in the east. He and his co-authors reviewed the literature and aggregated expert opinion to identify key variables that determine cougar habitat suitability – land needed to not be agriculture, be mostly covered by forest, not have too deep of snow, have moderate to low housing density in general and not be too close to those houses, and not be right next to a major road. They also factored in human-wildlife conflict, by excluding any areas with high livestock densities where the big cats would be likely to get into trouble and be lethally removed by wildlife managers as a result. they found 13 suitable habitat areas that met these criteria and were at least 10,000 square kilometers, across the Upper Midwest, Ozarks, New England, and Appalachia. They and others have argued that cougars are ecologically important, affecting many other parts of the ecosystem, and are therefore a key restoration target.
While cougars could eventually get there on their own if given enough time, there is a strong case to be made for giving them a helping hand. That's because cougars and other top carnivores can have some big benefits for society, including reducing the negative impacts of over-abundant prey like white-tailed deer. These "predation services" of cougars and other top predators are an area I've researched, along with collaborators. Using predator-prey population models, we found that if cougars recolonized the eastern US, they could reduce deer-vehicle collisions by 22% within 30 years, preventing 21,400 human injuries, 155 fatalities, and $2.13 billion in avoided costs. Based on data from South Dakota, we estimated that cougars are already saving around $1 million per year by preventing deer-vehicle collisions. And that's not factoring in other benefits cougars could have, like increased success of tree seedlings planted by foresters and browsed by deer, enhanced forest biodiversity (because over-abundant deer simplify forest structure and foodwebs), and maybe even carbon sequestration (because over-abundant deer reduce standing biomass and can impact below-ground carbon and biomass as well).
But of course, top carnivores like cougars also have real costs to humans living alongside them, from depredation of pets and livestock, to fewer deer for hunters and wildlife watchers to enjoy, to the fear that many people feel just knowing that there are cougars out there. And every now and then, people are attacked and even killed by cougars, although such instances are extremely rare. These perceptions of risk make people less tolerant of the big cats, impacting the likelihood of success for recolonizing populations whether that process is natural or assisted by humans.
Quantifying all of the costs and benefits to understand the "net effect" of predators and their ecosystem services and disservices is very difficult, and may even be impossible. But if we want to restore fully-functioning ecosystems, complete with top carnivores to regulate the system, we will need to take into account the true costs of living alongside them and mitigate these cost for those impacted. This means design and implementation of new forms of conservation finance so we can pay people for tolerating and providing habitat for a big, scary, and sometimes damaging cat in their neck of the woods. Cougar habitat credits, anyone?
(Note: I also published this as a LinkedIn Article, available here)