The coastal brown bears of southern Alaska are probably most iconically associated with salmon-eating, but seasonally available fish are only part of the diverse diet of these swaggering omnivores.

Dramatic video, taken and shared by fly-fishing guide Sam Vassar, shows a bear taking down an apparently full-grown cow moose along – and, more often than not, in – the Alagnak River. (Heads up: The footage is a little hairy, so if you're squeamish, look away now.)

The half-amphibious attack calls to mind some past high-profile videos of bear predation on the continent, including vintage footage of a sow grizzly wrestling down a bull caribou and a 2020 incident in which a big boar grizz killed a bull elk in the Yellowstone River, then luxuriated (that’s probably the best word) upon its remains to the awe of human spectators and the frustration of gray wolves keen on some good old-fashioned scavenging.

North American brown bears – the most widespread, interior, and silvery form of which is generally called the “grizzly bear,” with rough convention labelling the bigger coastal-Alaska version simply “brown bear” – can be important predators of moose. It’s probably safe to say most of that active carnivory centres on moose calves, which – like the young of elk, caribou, deer, bison, and musk ox – are opportunistically targeted by grizzlies (and American black bears), particularly in the late spring and early summer.

Last year, a summer wedding ceremony in Montana’s Glacier National Park came with a rather graphic, thoroughly wild backdrop courtesy of a grizzly bear dispatching a moose calf in the background. (A memorable saying-of-the-vows, needless to say.) Earlier that same year, and in that same Rocky Mountain park fast against the Canadian border, a grizzly nabbed one moose calf, but faced the considerable wrath of its mother upon returning to try for its sibling.

Bear witness?

That kind of best-defense-is-an-offense approach of a momma moose was also on display a few months ago in Alaska, with, this time, a black bear the determined but ultimately out-of-luck ursid. (Watching the ferocity with which that mother defends her calves gives you some sense for why moose, on average, injure more people in Alaska than bears do.)

And actually tackling an adult moose – the biggest member of the deer family, with the Alaskan subspecies being the biggest of all – as a potential meal is a bit next-level. Even wolf packs – overall the most significant predatory force that most moose in the Northern Hemisphere contend with – often balk at a healthy, ears-down, mane-bristling moose that chooses to stand its ground rather than flee. Heck, those flying hooves can pack a punch!

All that said, research in both North America and Eurasia (where moose are more commonly called “elk,” not to be confused with the North American elk or wapiti, a different cervid entirely) show brown bears can be capable, if occasional, hunters of full-sized moose. Studies on moose predation by European brown bears in Sweden and grizzly bears in Alaska suggest cow moose during calving season may be most vulnerable to the bruins.

Conceivably, though, bull moose might, like elk/wapiti, be at some heightened risk of bear attacks come fall, when they may be distracted and exhausted by the hormone-roiled action of the rut – and especially if they’ve been injured during its battles.

Short of a grizzly bear taking a shot at an American bison – which does, on occasion, happenthis big-bear-vs.-good-sized-moose showdown is about as heavyweight as predatory clashes go on North American terra firma, where moose rank as the second-heftiest ungulate after the bison and the biggest brown bears vie with polar bears as largest terrestrial carnivore (on the planet, actually).

Header image: Frank Vassen