The Prairie Cougar: examining the effects of a re-established predator population

Michelle Bacon and Mark Boyce

During the past decade, cougars (Puma concolor) have appeared in unexpected areas. Once the mammal with the largest distribution in the Western Hemisphere, cougars were extirpated from most of their range in the early 20th Century and in Alberta were limited to the southwest region of the province.

However, cougars now seem to be walking back into their former range. In October 2008 a cougar shot in Saskatoon had a radio collar showing it had originated in the Black Hills of South Dakota, 960 km from its final location. This was the second longest known dispersal of a cougar; the furthest – a 1,067 km stretch from South Dakota to Oklahoma – occurred in 2004.

Further east, cougars have made appearances in Manitoba, Ontario, Quebec, and as far east as New Brunswick. Whether these cougars are residents or transients is unknown, but it is clear that these elusive predators are re-occurring in areas where the current generation of wildlife and humans have not previously encountered them.

The Cypress Hills of south-eastern Alberta and south-western Saskatchewan hosts the most eastern confirmed breeding population of cougars in Canada. Although occasional sightings have occurred throughout the last 20 years, within the past 5 years tracks and sightings have increased significantly.

These large cats, having arrived via coulees leading from the Rocky Mountains in Alberta and/or from the Sweet Grass Hills, Bear Paw Mountains and Little Rocky Mountains in Montana – all of which are within 400 km – found a carnivore-free oasis of forest filled with abundant wild ungulates for the taking.

The inter-provincial park, a 400 sq km protected area surrounded by private ranches, rises nearly 600 m above the prairie grasslands and may be the perfect stepping stone habitat that could facilitate cougar gene flow and movement to more distant populations eastward. The return of cougars to an ecosystem dominated by wild ungulates also could result in changes in the abundance and distribution of prey, i.e. a trophic cascade, as has been seen in other areas where large carnivores returned. [Ed: see trophic cascade definition below] .

However, the persistence of this population depends largely on the human population living around the park. A recent change in Alberta regulations allowing private landowners to shoot cougars on their land, combined with an ingrained attitude of distrust toward carnivores, might provide a challenge for the cougar population to persist in the region. Indeed, since 2004 there have been 12 reported mortalities of cougars outside the park boundaries in Alberta and Saskatchewan combined. These numbers may decrease as the cougars –solitary in nature – establish firm home ranges and the population reaches carrying capacity.

The return of cougars to this area is expected to create a change from both ecological and human dimension perspectives. Our study is aimed at documenting habitat and prey selection of this re-established population. Our research will help determine whether there is a threat to the local ranchers, cottagers and tourists, and to their livestock and pets. We also will determine whether these threats vary by season, and whether human activity during the busy tourist season in summer influences movement and habitat selection of the cougars.

We hope the information we gain will lead to an understanding of the factors that contribute to the restoration of a large carnivore, and can assist in creating a management and conservation plan for cougars that will allow them to co-exist with wildlife, livestock and humans in the region.

During the winters of 2008-09 we are using trained hounds to catch cougars so that we can place Global Positioning radio collars on them. These radio collars allow us to receive fine-scale information about the locations of the cats every 3 hours. We are monitoring radiotelemetry data collected by the GPS collars to find clusters of site locations; these clusters are investigated as potential kill sites and if a kill is found we record data on the prey. Throughout the two year study we will be able to assess the proportion of each prey species in the cougar diet, and examine the location of kills as well as the home ranges of the cats.

In April 2008 we caught and placed radio collars on two cougars, an 82 kg mail and a 43 kg female. Throughout the summer and fall we tracked and located kill sites for the two cougars, and in 23 weeks of monitoring we found 29 kills by the male and 31 kills by the female.

Our male has a summer/fall home range of approximately 250 sq km and has been preying on large, wild ungulates. His diet thus far has mainly consisted of elk (35%), deer (41%) and moose (17%). We believe him to be probably the largest cougar in the area. Our female has a summer/fall home range of approximately 60 sq km, and has been preying primarily on deer – 88% of her diet thus far.

In mid-July we were investigating a GPS cluster and discovered her den site where she had hidden her four kittens. After downloading the GPS telemetry data the next day, we determined that the kittens were only 11 days old. It will be interesting to assess the survival of the kittens and to monitor their movements this winter through snow tracking. We plan on catching another four cougars this coming winter to further evaluate the population in the Cypress Hills, which we estimate to be between 8 and 12 resident adults.

We also have been using remote motion-sensor cameras to monitor wildlife populations in the park. Since February 2007 by setting these cameras on game and hiking trails we have captured 25 cougar “events.” Unlike other large cats, cougar have no unique markings that make them individually identifiable in photos. However we have captured different family groups at two locations in the park, and when combined with our home range maps of the collared cougars we are able to gain a sense of how many may be in the park and which areas they are frequenting.

The return of a large carnivore to this region signifies a change to this unique forested ecosystem of the Canadian prairies, and there will be inevitable conflicts between wildlife and human stakeholders in the area. We hope that by studying the cougars, we will assist local wildlife officials to create a management plan and, depending on our results, will alleviate some of the concerns about safety and livestock depredation.

On a broader scale, studying an area such as the Cypress Hills will help gain insight into the ecological significance of cougars in an isolated population and will lead to an understanding of how humans with various interests can co-exist within them.

Source: Federation of Alberta Naturalists, Nature Alberta, Vol 38, Nbr 4, Winter 2009

A tropic cascade occurs when a predator in the food chain suppresses the abundance of their prey, which releases the next lower level in the food chain from predation – or when ungulates are the prey, from hebivory.

The research study is a collaboration among the University of Alberta, Alberta Parks and Protected Areas, Alberta Sustainable Resource Development, Saskatchewan Environment and Parks Canada