JWM: How managing moose can stop wolf control in caribou ranges

To reduce the number of wolves that prey on threatened woodland caribou in British Columbia and Alberta, one strategy could be keeping down populations of their primary prey—moose.

“Wolves can recover [from population control] extremely quickly, within a couple of years,” said Michelle McLellan, a postdoctoral researcher with the University of British Columbia Okanagan. “So, if you have a large moose population, it results in a higher number of wolves killed during control efforts.”

Wildlife managers have been trying to stymie the decline of the southern mountain population of woodland caribou (Rangifer tarandus caribou) for some time in British Columbia and Alberta. One of their methods includes removing wolves (Canis lupus) from parts of the caribou range in an effort to reduce predation on caribou—a strategy that began in 2014 in British Columbia and a little earlier in Alberta.

But researchers wondered if keeping numbers of wolves’ primary prey species—moose (Alces alces)—low would have a similar effect. In some areas, moose numbers have increased due to logging, which opens up more foraging habitat for them. In these cases, wolves proliferate in response to their ample primary prey source. Since wolves occasionally take caribou when the opportunity arises, higher numbers of the predators put more pressure on the threatened ungulates.

In a study published recently in the Journal of Wildlife Management, McLellan and her co-authors examined how efforts to keep moose numbers at historical levels—before logging changed the environment—can result in a lower need to control wolf numbers with culling.

To manage for other factors that might be affecting an already complex ecological situation, the team only looked at areas free from cougars (Puma concolor) and white-tailed deer (Odocoileus virginianus)—species that can also have a direct or indirect effect on caribou numbers.

Cascading ecological effects

In central British Columbia and parts of western Alberta, the team examined wolf removals that occurred from 2014 to 2022. Managers removed over 1,900 wolves from these areas during this period.

McLellan and her colleagues found that when moose had been controlled to historical numbers, wolf removal was 3.2 times less than in areas where moose numbers had not been controlled.

A model they ran revealed that in areas where moose were maintained at historical levels, only 60 wolves would need to be removed compared to 200 in areas where moose numbers were much higher.

McLellan said that by only focusing on wolf control to conserve caribou, wildlife managers may be making their lives more difficult. “You might end up in a scenario where there are so many primary prey that it becomes more difficult to remove wolves,” she said.

But by controlling moose numbers in southern mountain woodland caribou ranges, either by directly culling or by liberalizing hunting quotas, wildlife managers might indirectly control the number of wolves.

This article features research that was published in a TWS peer-reviewed journal. Individual online access to all TWS journal articles is a benefit of membership. Join TWS now to read the latest in wildlife research.