(Photo | M Cathrae)
When thinking about the parameters of a typical wolf diet, a common conjuring of likely candidates resembles common prey species such as wild ungulates and ranched livestock. Perhaps the occasional hare or small rodent.
Many studies focusing on the dietary trends of wolves across North America do, in fact, point out that ungulates are a staple. Multiple studies have referenced moose (Alces alces) as making up over 80% of a wolf’s diet. White-tailed deer (the most common prey in Minnesota), elk, caribou, and domestic livestock tend to also be popular and common fare - polarizing the debate of both wolf management and reintroduction in many parts of America.
However, as the Voyageurs Wolf Project of Minnesota highlights in a recent social media post, skilled predators like wolves can sometimes leave us all surprised with what they fancy for a meal.
The photo, uploaded to Voyageurs Wolf Project’s Facebook page, shows an assortment of animal parts found in a wolf scat sample. (Photo | Voyageurs Wolf Project Facebook)
Voyageurs Wolf Project, a collaboration between the University of Minnesota and Voyageurs National Park to broaden knowledge on wolf ecology, uploaded an image of a dissected scat sample for a rousing game of “guess the remnants” this past week.
Separated from the hodgepodge of assorted bone and digested fur tufts were two different sets of claws - clearly belonging to two very different mammalian species.
The Not-So-Shocking
One set of claws was almost immediately identifiable to those of us in the trapping community. The elongated, rounded characteristics displayed a clear connection to a grazing prey species; but not of one commonly associated with wolf depredation. The claws clearly belonged to that of a beaver (Castor canadensis) - the common sub-aquatic rodent indigenous to most of North America.
The presence of beaver in wolf scat doesn’t come as a total surprise. Several studies referencing beavers as a somewhat common occurrence in a wolf’s diet have been noted for decades. I personally always had trouble wrapping my head around the concept myself - with beavers spending much of their time in or near the water, and armed with those razor sharp tree-cutting teeth, I found it difficult to envision predators like wolves and coyotes successfully stalking, subduing, and killing 60+ pound rodents with a fierce return bite. Could it happen? Certainly. But is it really as common as the research makes it seem?
A video uploaded to YouTube in 2015 changed my opinion; clearly depicting a wolf successfully running down and killing a beaver on land.
Any doubt was further removed three years ago, when I came upon not one but two beaver kills from predators here in New Hampshire, while surveying a nuisance beaver control job in late December. Curious once more was the nature in which both beaver carcasses (both within 50 feet of each other) were fairly close to the water’s edge, and both were only consumed from the hind-quarters and castor glands to the base of the tail. The animals’ remains from the hips upward were otherwise untouched. Very little blood was present, but the disarray in the earth around the kill area showed quite a struggle had ensued.
Watch as a wolf stalks and attacks a beaver on land.
Beavers are subject to these types of attacks while on land, foraging for feed via tree bark and small shoots of vegetation that grow around water sources. While beavers are unmatched once in the water, their agility on land is rather sluggish, and at times awkward, based on their body shape and size. Worn trails leading from the water’s edge to prime feed areas on land read like a roadmap to wayfaring predators.
One study from 2011 even found that beavers will quickly avoid their own common feeding trails once wolf urine is applied to the area. Of course, I suspect a wolf presence would likely need to be active for beavers to recognize, and more importantly, fear, those predatory urine markers as a threat.
Research has eluded to the fact that beavers actually play a potentially significant roll as an alternative food source in the summer months for wolves, with 60% of a wolf's diet being beaver in some areas during the summer.
The more Surprising findings
The other set of claws in the Voyageurs’ post seemed to stump inquisitive followers slightly more.
Guesses ranged from the claws belonging to cats like lynx and bobcat, to birds of prey, to a small bear, to wolverine and marten. Alas, the researchers at the Voyageurs Wolf Project feel pretty certain the other set of claws belong to that of a Fisher (Martes pennanti).
Fisher are dense-woodland animals, and regarded as very effective predators on land (aside from the wolf, apparently). They are also the fastest American animal in trees - built for chasing and catching squirrels. Once extirpated due to immense habitat loss and unregulated hunting, the fisher has since reclaimed many of its wooded haunts in Wisconsin, the Upper Peninsula of Michigan, and Minnesota - where the wolf scat sample was found.
A cousin to that of the wolverine, my level of surprise from word of finding fisher remnants in a wolf turd comes from the notion that, until now, there didn’t seem to be too many creatures on the landscape that would want to tussle with such a voracious (and tenaciously scrappy) mesocarnivore.
While other predators such as bobcats are known to kill young and vulnerable fisher and directly compete for prey and territory resources with the mid-size mustelid, I could only find reference to one scientific research paper that confirmed talk of a wolf killing a fisher.
A fisher (pekania pennanti) perched on a tree. (Photo | Holly Kuchera/Dreamstime.com)
One comment from a Facebook user on the Voyageurs scat photo included an image of a fisher he claims was “treed” by two wolves in Canada’s Elk Island.
So while this clearly isn’t the only instance in which a wolf has (in one way or another) preyed upon a fisher, it certainly seems to be the most detailed that I’ve found.
Researchers caution that there are limitations to the evidence of prey remains in scats. There is no way to know, definitively, if wolves actually killed the prey in the scat or just scavenged it. In other words, was the fisher specifically stalked and killed by a hungry wolf, or already dead from other causes when a wolf happened upon the carcass? That question is likely to remain open in this particular situation.
A “Varied” Diet
Either way, there’s no doubt a creature as adapt at killing as the charismatic wolf can be resourceful. Side note, I found the notion of passing of claws and bones to strike me as a seemingly rather painful experience. That said, many assert that the wolf’s relatively short intestine (compared to a human’s) no doubt helps with the passing of these undigested remnants. Nonetheless research has found that wolves have died from blockages; and I’m sure, that like most things in nature, it isn’t always pleasant.
And its not all living creatures that pass through the digestive tracts of resident wolves. Voyageurs researchers have noted an assortment of materials found in the stool samples of Minnesota wolves; such as pieces of butter wrappers, chunks of rubber, and pieces of milk cartons, to name a few.
The obvious reality, wolves are both scavengers and skilled hunters, and will eat just about anything they catch - large ungulates to small woodland critters.
Suffice to say, when venison just isn’t on the menu, the resourceful and skilled hunting instinct of North America’s wolves will ensure that regardless of what crosses their path, odds are good they won’t go too hungry for too long.
A wolf walking down a national park road with a caribou leg. (Photo | NPS Ken Conger)