Hunting may create cougar problems
IF THE COUGAR IS ANYTHING like its fellow carnivore the grizzly, then the method we’re using to try to solve our current problems with cougars may well aggravate rather than alleviate them.
Rob Wielgus, director of the Large Carnivore Conservation Laboratory at Washington State University, turned the Canadian wildlife management world upside down with his graduate and postgraduate research showing that trophy hunting of grizzly bears in the Kananaskis region of Alberta was neither beneficial nor benign to the resident population. His work indicated that trophy hunting would lead to the extinction of the grizzly population in 15 to 20 years.
“I bought into the old paradigm when I started my work,” says Wielgus. That paradigm was the same as that used for management of prey species. It held that removing adult male animals increased food for females and offspring. As a result, populations would grow.
Wielgus’s research showed that when a dominant adult male grizzly is killed, younger males from the surrounding area migrate into his territory. The young males will attempt to kill off any cubs in the territory as a means of inducing the females to come into heat. Otherwise, these males have to wait until the cubs are weaned to mate with the females. That can take up to three years.
In order to avoid the young males, female grizzlies with cubs hide in high mountain valleys. Wielgus had noticed this phenomenon when he first went to the Kananaskis, and like others, he thought it was because the food there might be better. But the reverse is true. These areas have food of poor nutritional value, primarily Indian potatoes. The males and sub-adult females that stay at lower elevations eat more nutritious horsetail, cow parsnip, and elk calves.
Ultimately, less nutritional food will result in litters of one cub, rather than the usual two or three, and the population will decline.
Wielgus would like to determine whether cougar respond to hunting in the same manner. “There are more cougar now, and they’re causing trouble,” he says.
Again, conventional wisdom holds that killing adult male cougars will decrease both predation and problem interactions with humans. Wielgus disagrees.
“I suspect that hunting of adult male cougar is causing the trouble,” he says. Hunters don’t go after the small cats but choose big animals, those that are often dominant. If his hypothesis is correct, killing the large animals brings younger males into the territory. It’s these males that usually cause trouble.
“If you kill one dominant male cougar, three sub-dominant males come to the funeral,” says Wielgus. So instead of less predation and fewer problem interactions, there are more.
Wielgus will be testing his hypothesis this winter with the help of Dennis Murray, a wildlife ecologist at the University of Idaho. One of Murray’s graduate students will be doing the field work and will join Wielgus’s graduate students in monitoring radio-collared cougar in Washington’s Selkirk Mountains.
Wielgus’s students are studying cougar and prey interactions. Hugh Robinson is researching the predation of mule deer, which is caused by the effect on cougar populations of increased numbers of whitetailed deer, and Jon Almack studies the same problem for endangered caribou.
Early results support Wielgus’s argument that the hunting of male cougars does not reduce predation but may actually increase it because of immigration. But Wielgus concedes the latter is speculation at this point.
“We have to capture and collar more cougars this winter to see if immigrants actually do come in.”