Intensive hunting may cause long-term damage to wolf packs and ecosystem, research finds
The study published in Functional Ecology examines the unwanted ripple effects of hunting on the stress and reproductive systems of wolves in Northern regions of Canada. Photos by Marco Musiani, University of Calgary
Researchers at the University of Calgary studying the heavily hunted wolf population in the Taiga and Tundra regions of Nunavut and the Northwest Territories have found the animals have elevated levels of stress and reproductive hormones that could be damaging their long-term health. The insight offered from this work could benefit wildlife management practices.
Every year, hunters in the Northern regions of Canada trap wolves or hunt them on snowmobiles to harvest their pelts. In some areas, government authorities cull wolves to manage their numbers so that fewer wolves take prey. Researchers studied the hormones found in tufts of wolf hair from these heavily hunted populations and compared them with hormones found in the hair of other groups of boreal forest wolves that have a considerably less-intensive hunt.
They found much higher levels of the stress hormone cortisol in the Taiga and Tundra wolves. “They have a more stressed life,” says Judit Smits, professor in the Faculty of Veterinary Medicine, and co-author of the study published in Functional Ecology. “We know from other species including humans, dogs and wildlife that chronically elevated levels of these hormones lead to things such as immune suppression which means they’re more susceptible to disease, and they’re not as well equipped to deal with everyday challenges of life.”
Researchers also found elevated levels of progesterone, a hormone produced during pregnancy, which indicates an unusually high proportion of breeding females. Normally only one female in a pack produces pups, so having a high number of pregnant females in one pack indicates “a broken social structure which is disrupting their normal reproductive strategies,” says Smits. “A normal wolf pack has a very important social structure, with one breeding male and female and all the others know what their role is.”
Humans usually view wolves as competitors over shared prey such as caribou in the North and livestock farther south, which is why wolf packs are often subject to severe population reductions.
“We often manage wildlife assuming that we can hunt and control population numbers without any unwanted ripple effects, but this assumption is not sound,” says Marco Musiani, associate professor in the faculties of Environmental Design and Veterinary Medicine, and one of the study’s five co-authors. The lead author is Heather Bryan, one of Smits’ former PhD students.
Smits adds, “Studies like this one demonstrate lasting effects on stress, increased reproduction and potentially disrupted social structure of wolves.”