June 14, 2012 | 15
Cougars (Puma concolor) have not lived in Oklahoma, Missouri and other midwestern states since the beginning of the 20th century. But now the cats are returning to and repopulating some of their former Midwest habitats, according to research published Thursday in The Journal of Wildlife Management. (The North American cougar is typically identified as the subspecies P. c. couguar, although cougar taxonomy remains a matter of scientific debate.)
Cougars once lived throughout most of the U.S. and Canada but state-sponsored bounties put in place to protect livestock and humans from what were often deemed “undesirable predators” led to the cats’ extermination in the east and Midwest. (The Mountain Lion Foundation has a timeline of cougar bounties and extirpations as they were wiped out from east to west.) By the second half of the 20th century they mostly restricted to states and provinces west of the Rockies. (The critically endangered Florida panther, Puma, or Felis, concolor coryi, is accepted as a separate subspecies.)
Things started to turn around for the cougar in the 1960s and 70s when, one by one, the bounties were rescinded and states made the animals a managed-game species. Today they are classified as game species in most states and a “specially protected mammal” in California. This allowed their populations first to grow and then to expand their territories. Breeding populations were established in the Black Hills of South Dakota in the 1990s then the North Dakota Badlands and western Nebraska in the following decade. The animals appear to have continued their eastward spread from those three locations. They have now been seen in Oklahoma, Missouri, Arkansas, Illinois and several other Midwest states and Canadian provinces, and the sightings are growing more frequent, according to data compiled in the new paper.
The expansion has been driven by the cougars’ solitary, territorial nature, explains the paper’s lead author, Michelle LaRue, research fellow for the Polar Geospatial Center at 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 cornf