There have been a great many blogs and articles by a great many people written on the plight of the caribou of British Columbia. The species has been listed as threatened under the species at risk act (SARA) and as a large mammal gained a lot of news coverage. Discussion and controversy over culls and vehicle access have raged over many discussion boards. The effectiveness and morality of population controls is beyond my scope here, but you can wade into it at your own discretion. I want to discuss why wildlife managers and researchers have proposed reducing moose populations to save the caribou.

Moose don’t hunt and kill caribou. They don’t even use the same kinds of habitat; moose prefer much denser forest at lower altitudes. So why would people consider moose a threat to caribou. Because more moose, means more wolves, that hunt caribou.

By National Park Service [Public domain], via Wikimedia Commons

Why, it can’t be just that simple? That’s a little more complicated. It is based on the way expanding wolf populations disperse and make hunting decisions.

When a population of wolves grows dense enough, like with any species, parts of the population are forced to move out of the most preferred habitat to the periphery. Driven by competitors and hunger for uncontested territory and prey the wolves will follow the moose that are driven by the same problems up the mountains and out of the habitat both species prefer. This results in the moose, who still prefer the densest forest they can find, pulling wolves into contact with the territories of caribou.

This is when the basic rules of foraging begin to hurt the caribou. Wolves may be hunting for moose but if an easy meal crosses their path it will always be an easy decision for a wolf. Pregnant cow caribou or new calves are an easy meal. The wolves are unlikely to target a prime bull but pick off every vulnerable caribou that wanders too low.

This easy meal preference is why managers have proposed targeting moose over the wolves themselves. Weakening a pack is unlikely to change their preference for the easiest meal around but they hope that by shrinking the moose population they can pull the wolves back down the mountain.