Quirks & Quarks

To save endangered caribou, shoot a moose

Threatened woodland caribou can be protected from wolves by removing invasive moose from their habitat
Mountain Caribou in British Columbia observed during a population census (Hans Mohr cc-by-4.0)

Canada's woodland caribou are in trouble. For decades the populations in Alberta and the mountains of BC have been shrinking drastically. The biggest problem is probably us. We've invaded and disturbed their habitat for logging, oil and gas.  But the immediate problem is wolves. These fearsome predators have been taking caribou in numbers that are simply unsustainable. In an effort to give the caribou a break the Alberta and BC have been culling wolves. Killing hundreds of them.

It's been enormously controversial. And according to a new study - it may also be the wrong way to go. 

According to a long-term research project by Dr. Rob Serrouya, the Director of the Caribou Monitoring Unit at the Alberta Biodiversity Monitoring Institute, and his colleagues, to save caribou don't shoot wolves - shoot moose.  They've found that invasive moose and white-tailed deer - who do well in caribou habitat disturbed by humans - are supporting a larger than ordinary number of wolves. Dr. Serrouya says the caribou are just "bycatch" the wolves are taking when they have the opportunity. When moose were removed by sport-hunters, many wolves leave for richer areas, and caribou numbers can stabilize.

This interview has been edited for length and clarity.

Tim Caulfield: Why did you think it was a good idea to shoot moose to save caribou from wolves?

Rob Serrouya: Well we have to step back and look at the whole caribou problem across North America. When you remove trees with fire or logging you get more shrubs for about 30 to 50 years and those shrubs are what feed white tailed deer and moose - and both of those species are expanding in many areas. When you have the expansion of deer and moose, along come wolves and cougars and the caribou are essentially bycatch they're like incidental take.

Mountain Caribou in British Columbia, Canada, moving to low elevation during spring. (Robert Serrouya, cc-by-4.0)
TC: So the wolves are dragging in their predators to the world of the caribou.

RS: That's exactly right. So removing wolves on its own is just a Band-Aid. It's just treating a symptom not the cause. And that's been done a lot in Alberta, and just very recently a little bit in British Columbia.

TC: How did you manage to test this idea.

RS: So we noticed that there was a lot of moose and that the government was going to reduce them a little bit to help with tree plantations in that kind of thing. So we said OK let's turn this into an experiment to maximize our learning. So we said there is the treatment area north of Revelstoke and then there'll be an adjacent reference or control area where moose are not reduced. So that's how the stage was set.

TC: So what strategy did you use to remove the moose

RS: It was simply an increase in sport hunting permits particularly for female moose but also for trophy moose.  All these animals were used for food to feed people and that basically generated income from the province by reducing moose to historic levels levels that were existing prior to broad scale logging.

TC: So what was the result. What did you find from this big project.

RS: Sure enough the moose were reduced in the treatment area and they didn't decline in the control or reference area. Then we noticed that wolf numbers were declining. We noticed that in response to the moose reduction the wolves in the treatment area dispersed. They left the area which resulted in a decline in numbers. And we also noticed that fewer wolf babies were being produced in that area.

And then we of course monitored caribou and that was the $64000 question.  So we found that adult survival increased in the largest herd in the treatment area. And those numbers have now been stable for 14 years which I would argue out of about 65 herds in B.C. in Alberta is the most stable herd.