Woe to the creature—two-legged or four-legged—who rouses the ire of a mother bear! That whole ferocious "mama bear" attitude is very much on display in a couple of recently posted videos out of northwestern North America.

Exhibit A comes from the outdoor-resort hub of Whistler, up in the Coast Ranges of southwestern British Columbia, Canada. Jason Coleman shared footage on Instagram showing a well-known area female (sow) black bear, nicknamed "Ruby," defending her cub against an oncoming sow grizzly bear (one "Hershey"):

The brief clip opens with the griz in close pursuit of the black-bear cub, then Ruby barreling toward the larger brown bear with lowered head. The bellowing grizzly falls back on her heels as the mother black bear actually rears up and swats at Hershey—quite the moxie, when one considers the usual grizzly/black-bear relationship (more on that in a bit). The fight, such as it is, ends quickly as Ruby wheels around and flees after her cub, the griz charging after. But Coleman reported via the comments section for his video that the black bears indeed escaped: "The cub got to a tree in plenty of time as the mother joined her—as soon as she got away from the grizzly. [...] The grizzly ended up with a small cut on her neck and the black bear was seemingly uninjured."

In the video comments, Coleman also noted that he's "seen a larger male black bear aggressively, and successfully, chase this same grizzly away."

And Exhibit B: Up at the famous salmon-scarfing bruin haven of Brooks Falls in southern Alaska's Katmai National Park and Preserve, onlookers recently filmed a brown-bear sow usher her twin cubs up a riverside tree, then rocket through the flow with open jaws to deter a significantly heftier adult male. The rather hair-raising roaring as the two bears face off is worth the price of admission.

And, finally, Exhibit C: Another mama brown bear with the same in Alaska giving up on a fresh-caught salmon prize so as to confront a boar coming at her cub:

That kind of full-frontal aggression is understandable, given the very real threat adult male bears pose to cubs. Infanticide can be a major cause of mortality for ursid youngins across multiple species. Given the substantial size discrepancy between boars and sows, it's no surprise a mother bear would much prefer to simply exit the scene posthaste with her progeny safely in tow when a male appears. But in cases where a boar is too close, sows defending their cubs will (as the Brooks Falls footage shows) risk their own lives to actively confront and even, if necessary, battle the bigger bear. As these cases suggest, a boar will often back down: Even with a big-time size advantage on your side, would you really want to tangle with a willing-to-die, ferociously protective mama bear?

The Whistler, B.C. event is interesting because of its interspecies angle. American black bears are, on average, smaller and less massive than grizzly bears, which also tend to be more dispositionally aggressive. (A quick note: Save for the genetically distinct-enough Kodiak bear of an Alaskan archipelago, all North American brown bears are currently classified as the same subspecies and generally called grizzly bears, but folks in southern Alaska often refer to coastal grizzlies—such as those in Katmai—simply as brown bears.) Black bears are much better tree-climbers than their hulking silvertip cousins, so their preferred method of dealing with an encounter with one is scrabbling up the nearest trunk. Mother black bears are also apt to do the same if a male black bear shows up (again, the infanticidal risk is real).

Grizzlies are known to occasionally prey on black bears, and not just cubs. So there's good reason for black bears, especially in grizzly country, to stick as much as possible to timber, where their arboreal prowess gives them better odds of escape. Research also suggests that, where they share the landscape with the often crepuscular and nocturnal grizzly, black bears may spend more time out and about in daylight hours—a form of "temporal segregation" that may similarly help Asiatic black bears steer clear of sympatric brown bears.

Of course, it's not always black-and-white, as Coleman's observations from Whistler demonstrate. For further flip-flopping of the status quo, check out this Yellowstone black bear successfully defending a carcass from a grizzly:

As well as, from last year, this black bear pushing off a sow brown bear in defense of a fishing hole in Alaska:

But these are more the exceptions that prove the rule. And it's not clear whether, say, Ruby the black bear would have been quite so bold in her defense had the attacking grizzly been a boar, where the weight-class mismatch would have been all the more extreme.

Bears dealing with one another makes a fascinating subject. But this also leads us to a closing message of direct practical benefit to our own (rather volatile) species. Here on the back-end of the Northern Hemisphere summer, hikers and campers and berry-pickers are, in many areas, pursuing their outdoor recreation alongside mother bears out teaching their rapidly growing cubs the ins-and-outs of ursine life. Add to that the fact that, around now or in the very near future, both black and grizzly bears are entering hyperphagia: a period of intensified feeding—a sort of semi-desperate ramping-up of chowing down—with the goal of putting as much fat on ahead of their big winter sleep (and fast).

Long story short, proceed in bear country this season with caution, situational awareness, respect, and basic bear-safety know-how. Although the danger posed by grizzlies is overblown, there may be no other critter on the North American continent you less want to run upon suddenly at close quarters than a mother griz with cubs. (Although a grizzly, male or female, who's defending a carcass is up there as well.) In an ideal world, she'd surely rather run full-tilt away, but if she feels she doesn't have the time, she might opt to do what that Brooks Falls sow did and confront the perceived danger head-on. (A mother black bear is generally more likely to send her cubs up a tree if she feels threatened by people than to go on the offense, but any wild animal's unpredictable and you still want to avoid a sudden close-range encounter.)

Fortunately, abiding by bear-country etiquette—including carrying bear spray, making plenty of noise, and hiking in groups—goes a long way toward reducing your chances of landing on the receiving end of a mama bear's wrath. And thereby letting you more deeply enjoy the special, in-the-moment thrill that comes with sharing the countryside with such splendid beasts (and their little beastlings).

(Bone up on bear safety courtesy of Parks Canada and the U.S. National Park Service.)