ABOUT THE PROJECT
The Voyageurs Wolf Project, which is a collaboration between the University of Minnesota and Voyageurs National Park, was started to address one of the biggest knowledge gaps in wolf ecology—what do wolves do during the summer? Our goal is to provide a comprehensive understanding of the summer ecology of wolves in the Greater Voyageurs Ecosystem in northern Minnesota. Specifically, we want to understand the predation behavior and reproductive ecology (e.g., number of pups born, where wolves have dens, etc) of wolves during the summer.
Throughout the winter, wolves hunt as packs and kill large prey such as moose and deer, but once wolf pups are born in the spring, wolves become more solitary predators, returning to and from the den or rendezvous site between hunting bouts. Yet the predation behavior of wolves during the summer in boreal ecosystems and how wolf predation habits influence wolf pup survival are poorly understood.
During the summer, wolves primarily hunt and kill small prey such as beavers and deer fawns but it has been quite challenging to study wolf predation on small prey during summer due to two main problems. The first is that observing wolves during summer is extremely difficult because of the dense vegetation, making it virtually impossible to visually observe wolves hunting and killing deer fawns and beavers.
Thus, the only feasible way to understand where wolves are traveling and hunting prey during summer is by attaching GPS-collars to wolves. A common method for locating predation or kill sites from elusive predators is by searching clusters of locations (i.e., areas where predators have remained relatively stationary) from GPS-collared animals and looking for evidence that a kill has occurred. But this is where the second problem comes in. Wolves can almost wholly consume beavers and deer fawns in a short period of time (in 20–40 min sometimes) leaving little of that kill for researchers to find later in the field. It is quite difficult to understand the predation behavior of wolves if you cannot observe wolves hunting and killing their prey, and you cannot find where they are making kills by tracking them.
When we started the Voyageurs Wolf Project, which blossomed out of a collaboration between Voyageurs National Park and Northern Michigan University, we had to develop rigorous search methods that allowed us to successfully locate where wolves were killing beavers and deer fawns. We quickly realized why it was so hard to find these kills in the field—most of the time all that would be left of a wolf-killed fawn or beaver were hair, a few bone fragments, and maybe the stomach contents. Such kill sites are a far cry from the huge scene that is left after wolves bring down a moose or deer. Through substantial time and effort in the field, we realized that finding these kills was possible but required a keen eye, training, and an attention to detail. Our method for finding kills entails fitting wolves with GPS-collars and intensively searching ‘clusters’ of GPS-locations where a collared wolf remained stationary for >20 minutes. We spend long periods at these clusters often looking for the slightest clues—a broken branch, a small patch of matted grass, a small disturbance in the leaf litter—to indicate a kill might have occurred. Finding these kills is undoubtedly challenging and requires significant training. For example, we found untrained field technicians are only able to find 30% of wolf-killed beavers and 13% of wolf-killed fawns.
In addition to finding where wolves are killing prey, the GPS-collars reveal the locations of den and rendezvous sites, which is where pups are kept during the summer. By gathering detailed information on both the predation behavior and reproductive ecology of wolves, we are able to connect critical facets of wolf behavior during the summer to important ecological factors, prey populations, and human interactions. Given initial results of our research—which was described as
“a breakthrough" by international wolf experts—we have an unparalleled opportunity to provide critical information for the successful conservation and management of wolves, their prey, and the southern boreal ecosystem. This work benefits not only Minnesota’s iconic Northwoods, but boreal systems around the globe from North America to Asia.