Winter in the Northwoods of Minnesota is in full swing and that means our work to estimate wolf pack and population size is as well. Estimating the size of any wildlife population comes with its own idiosyncratic challenges unique to that species. One of the biggest challenges for estimating the size of wolf populations is that wolves are elusive, very wary of people, and they have huge territories (in our area they are >125-150 km2).
Traditionally, biologists estimated wolf populations in forested environments (like the Greater Voyageurs Ecosystem, MN where we do our work) by getting up in an airplane and counting the number of wolves in each pack in their study area, or by searching for fresh wolf tracks on the ground and trying to determine how many wolves were traveling together in each pack. Both of these methods provide an estimate of the number of wolves in a pack. Biologists would then add up all of the wolves in each pack to yield a population estimate. Admittedly, this is an oversimplification of the process but captures the general premise of how this was (and still is) done.
However, both of these methods can be problematic. Interpreting wolf tracks in the snow requires good tracking condition, knowledgeable trackers, and an understanding of pack territory boundaries to know which pack the tracks belong to. On the other hand, flying in an airplane looking for wolves requires good flying conditions, that the wolves are visible and not hidden in the forest, and is quite expensive ($250-350/hour) relative to other methods.
In the early days of our project, we used a combination of flying, track counts, and trail cameras to estimate pack sizes. However, through time, we realized that trail cameras are by far the most efficient and cost-effective tool for the job. Because of this, trail cameras are the only tool we use to estimate wolf pack and population size.