Map: Chris Brackley/Can Geo
One of those places is Cypress Hills Interprovincial Park, a forested oasis in a sea of agricultural land that straddles the border of southeastern Alberta and southwestern Saskatchewan. Along with his students, Mark Boyce, professor of ecology at the University of Alberta in Edmonton, studied cougars in the park from 2007 to 2014. At one point, the team found one of the highest densities of cougars in North America — roughly six to eight animals (including kittens) for every 100 square kilometres. “There was so much food for them, they just had a heyday,” says Boyce. With abundant deer and elk to feast on, the cougars also appeared to have little interest in livestock on surrounding farms.
Since then, cougars have established themselves in Saskatchewan and are regularly sighted in Manitoba. Newly independent cougars will travel great distances to find new territories. One young male travelled 750 kilometres from Cypress Hills eastward through the agricultural belt of northern Montana and southern Saskatchewan. It padded soundlessly through rugged terrain and moved like a shadow under the cover of brush along wetlands and waterways, perhaps feasting on white-tailed deer to sustain the journey.
While deer are thought to be a cougar’s preferred food source, researchers have found evidence that some cougars specialize in other prey. “We documented one big male in the Nordegg area that in one year killed 17 wild horses, five moose, four elk and two deer,” says Boyce, adding that the horses weighed more than 450 kilograms each. He points to another case nearby where in 1993 and ’94 a female cougar zeroed in on bighorn sheep in an area known as Ram Mountain, Alta., killing nine per cent of the population and 26 per cent of the lambs in a single winter. “She had a pretty substantial effect on that local population,” he says.
Darlington has also been observing this behaviour in a bigger female in her study area, who seems to prefer feasting on young moose. A moose meal lasts longer — up to 12 days, as opposed to the meat of a deer that staves off hunger for only a week. Understanding what cougars are eating and where is a critical piece of Darlington’s work, aimed in part at understanding patterns of cougar predation on mule deer. Unlike their proliferating cousins, mule deer have been declining across their range since the 1950s. In two of Darlington’s study areas, mule deer are killed more by cougars than by other predators. Still, whether or not cougars are contributing to declines remains to be determined, as researchers tease out the role of other factors such as invading white-tailed deer and landscape changes from clearcuts and forest fires.