the University of Minnesota. “When a female cougar has males they have to disperse away from where they were born,” she says. This prevents the males from inbreeding with their female relatives and helps them to avoid conflicts with older, more powerful males. “As the different pockets of available territory become no longer vacant they have to go elsewhere. That’s what we think is happening. There are no more pockets of vacant habitat or territories left in the west. They’re forced to go elsewhere, and elsewhere happens to be the Midwest where there’s habitat but no competing cougars.”
LaRue and her fellow researchers examined 178 confirmed Midwest cougar sightings from 1990 to 2008. These included carcasses (animals killed by cars, trains or hunters) as well as scat and tracks, along with camera and video evidence. The number of confirmed sightings during this period increased steadily each year, from two animals in 1990 to 34 in 2008. By comparison, the total population of cougars in North America is estimated at around 30,000 animals. Of the 56 carcasses found, 76 percent were male, typical of the gender’s role as the primary dispersers of the species.
“They’re doing what we think is a stepping-stone dispersal,” LaRue says, “going from a primary source to another patch of habitat, establishing that habitat and then moving farther and farther east.”
Co-author Clayton Nielsen, assistant professor of forest wildlife in the Cooperative Wildlife Research Laboratory at Southern Illinois University, Carbondale, says DNA evidence taken from some of the carcasses further proves the eastward migration by linking the animals to the genetics of existing populations. “In the cases where those samples were analyzed, we could pinpoint the specific states where those animals originally came from,” he says.
Cougars are generalist predators, so LaRue says they can select any habitat with enough prey. They have also been shown to walk hundreds of kilometers in search of new habitat. “They have no problem traveling through cornfields or prairies for long distances if they have to,” she says. But cornfields and prairies aren’t suitable habitat for the cougars to settle in. She says they require forest cover, rugged terrain and dispersal corridors (typically rivers) that allow easy migration for both the cats and their prey. “They’re a stalk-and-ambush predator so they need places to hide,” she says.
LaRue says this is probably just the beginning of cougars recolonizing the Midwest. “Now we can start asking more questions: Where are they going to end up, how many are they going to be, and how are they going to interact with their ecosystems?” In the paper, LaRue and her co-authors suggest that wildlife professionals “begin to think about public awareness campaigns in areas likely to encourage dispersing cougars” because people in these Midwest states are not used to living with large predators. A good model is the California Department of Fish and Game’s Keep Me Wild campaign, which offers tips on coexisting with cougars and staying safe near them. They also suggest the more eastern states follow the lead of Nebraska and Missouri and develop conservation strategies for the animals.
The Midwest might not be the cougars’ final stop in their habitat re-expansion. Last year a male cougar traveled at least 2,400 kilometers from South Dakota to Connecticut before being killed by an SUV.
“The recolonization of former range by cougars is one of the most significant changes in the wildlife landscape of the U.S. in the last few decades,” says Howard Quigley, Teton Cougar Project director and executive director of jaguar programs for Panthera, which was not involved in this study. “One key to the future—and the successful colonization—will be the presence of enough good habitat to support resident cougars.” He also says government agencies, educators and communities will need to come together to develop plans to coexist with their new carnivore neighbors.
In other cougar news, another study published June 13 in Biology Letters tracked animals in Chi