Overharvest of cougars can increase negative encounters between the predator and humans, livestock and game, according to a 13-year Washington State University research project. Based on this, the Washington Department of Fish and Wildlife is implementing a new cougar management plan.
Starting in January, Washington will employ equilibrium management - hunters will remove no more than the surplus of animals that would be generated through natural reproduction.
This means that each of the state’s game management units will have a quota allowing for harvest of no more than 14 percent of that area’s cougars. Once the limit is filled, cougar hunting will be suspended for the year in that unit. Hunters will be allowed to take their tags to other units that haven’t reached the limit.
For years, cougar management operated on the presumption that every cougar shot meant one cougar less to prey on livestock, game and pets. But the 13-year study headed by Rob Wielgus, director of WSU’s Large Carnivore Conservation Lab, has overturned that presumption.
After years of data collection, researchers made a surprising observation. Whether hunters killed 10 percent or 35 percent of cougars, the population remained the same. The old paradigm of wildlife management would explain this by saying the remaining population increased reproduction to make up for hunting. But this was not the case.
In fact, reproductive success actually decreased. Data showed that adult males, "toms,” are intolerant of adolescent males and will kill them to maintain their territory and breeding rights. Juvenile males can only survive by avoiding adult males. When hunting removes most adult males, the adolescent males survive and cause all sorts of trouble.
While adult cougars tend to avoid humans and livestock, juveniles are less cautious: "They’re teenagers,” explained Wielgus. "They’re sexually mature, but mentally they’re not all there.”
This is compounded by the fact that adolescent males have larger territories than mature toms, but don’t maintain exclusive territories as do adult males. Livestock and elk herds might have one mature tom in the area, but removing that tom could bring in three or four adolescents, multiplying troubles.
Without adult male protection of females and their litters, infanticide becomes a problem, as the young toms kill kits to bring the mother into heat and improve their breeding chances. The females try to protect their litters by moving higher in elevation, away from dangerous adolescent males, but also away from plentiful whitetail deer and into terrain occupied by less abundant prey such as mule deer, bighorn sheep and woodland caribou. Thus marginal game populations suffer.
Research methods included capturing cougars with hounds and attaching collars with global positioning system receivers and radio transmitters. The collars reported the cougars’ locations six times a day, allowing researchers to generate valuable data on cougar migration, reproduction, prey and mortality.