Outside humans, the overall numero-uno predator of beavers is the grey wolf. Research over the past decade or two in particular has gone a long way toward illuminating this particular hunter/hunted dynamic. That said, it remains a somewhat obscure subject—not least because of how hard it is to directly observe interactions between the two critters: the one the biggest wild canid in the world, the other the second-biggest rodent in the world—and a semiaquatic, mostly nocturnal engineer renowned for its ability to sculpt landscapes.
Well, here's some special footage (credited to Janek Joab) captured in April in Estonia, home to roughly a few hundred wolves belonging to Europe’s Baltic population. Shared over the social-media channels of the Voyageurs Wolf Project, a Minnesota, USA-based research program, it shows a dramatic interaction indeed: two wolves vigorously attacking a beaver along a nighttime stream.
Grey wolves and beavers overlap geographically across broad swaths of North America and Eurasia (and once overlapped a lot more), most extensively in northern temperate and boreal zones. Other carnivores will prey on beavers: everything from the red foxes and golden eagles that'll snatch the odd baby beaver to wolverines, pumas, and brown bears capable of dispatching full-grown individuals. These paddle-tailed, web-footed, tree-felling rodents aren't especially easy prey, though.
For one thing, they can seek refuge underwater or within the well-armoured lodges they commonly construct in both existing lakes, wetlands, and sluggish riverways as well as the backwater ponds they themselves form via dams. For another, they're hefty—they may weigh better than 27 kilograms (60 pounds)—and their epic incisors, which drill through bark and wood at an impressive rate, can also be defensive weapons. And they've got their own communal alert system: Famously, they'll thwack their broad, scaly tails on the water's surface ahead of diving to warn other beavers of potential threats.
Another recent non-Minnesota video shared by the Voyageurs Wolf Project demonstrates how hard it is for a smaller wild dog to subdue an adult beaver. That video, courtesy of the Traprock Ridge Land Conservancy in Connecticut, shows an ambitious coyote do its darndest to take down a beaver it comes across onshore in the snow:
Despite a whole lot of tail-tugging, though, the "songdog" comes up empty handed. As the Voyageurs Wolf Project notes in its caption: "Coyotes, unlike wolves, simply do not have the strength and size to routinely kill beavers, especially large adult beavers."
Grey wolves have been documented regularly hunting beavers across many parts of their shared range, from Alaska, British Columbia, and Alberta to Belarus, Latvia, and Russia. Much recent research into how (and how much) wolves prey on beavers has gone down in the study area of the Voyageurs Wolf Project: the Greater Voyageurs Ecosystem (GVE) of northeastern Minnesota, a heavily timbered and watery wildland on the doorstep of Canada that includes Voyageurs National Park as well as surrounding acreage. Tracking GPS-collared wolves, researchers have found that beavers are a major prey item here, especially in summer; beaver meat has contributed as much as 88% of the May diet of particular wolf packs.
Late spring and early summer represents a peak in wolf predation on beavers in the GVE, as the canids—commonly roving as singletons or in small groups as packs raise litters—target younger beavers dispersing to create new (or resurrect old) beaver ponds. As summer ripens, the seasonal flush of vulnerable white-tailed deer fawns sees many GVE wolves shift their focus away from beavers somewhat. But they resume intensive "beavering" again in late summer and fall, as the rodents spend fair amounts of time out of the water to rustle up food stores for the impending winter.
Beavers are significantly less vulnerable to wolves in the GVE (and many other higher-latitude reaches of the Northern Hemisphere) during the wintertime, on account they're cruising around under the icy roofs that form over their slackwater abodes and huddling within snowed-in lodges. Ungulates are often the go-to wolf nosh during those frosty months, with the timing of fall "ice-up" and spring "ice-out" determining when wolves are doing most of their yearly beaver-hunting. (That said, wolves continue to opportunistically snatch beavers in winter.)
The Greater Voyageurs research shows that wolves employ specialised hunting methods to try for beavers in that main spring-through-fall window. Those strategies are rather "un-wolfish" when one considers the classic running-prey-down mode pack-hunting canids are best known for. Wolves in the GVE often stake out in catlike ambush along beaver hotspots, such as lodges, canals, and feeding trails. Sometimes for a heck of a long time, too: The Voyageurs Wolf Project has documented wolves lying in wait for up to 30 hours at such spots.
Beavers have a keen sense of smell, but not terribly good vision, so wolves mainly position themselves at these stakeouts downwind and close enough to where the buck-toothed beasties come ashore—or waddle along their foraging corridors—that they've got a decent shot of snatching them via just a short burst of speed.
Research out of the GVE suggests wolf predation doesn't significantly impact the overall beaver population, which is ample, but can shape the geography of beaver activity and the significant ecological ripple effects thereof. For example, wolves may squelch the creation of some wetlands by picking off a proportion of the young dispersing beavers questing for new habitat. Given all the effects a beaver dam can have on stream and riparian function—from expanding soggy habitat to slowing flow and modifying water chemistry—this wolf impact has landscape-level implications. But those are landscape-level implications that have been a reality for a long, long time, and are part of the grand choreography of northland ecology.
Top header image: Stefan Rusche/Flickr
Predator vs Prey
WTF!?
Predator vs Prey
