MARINE MAMMALS ON THE MENU

A veritable brown bear buffet! Photo taken by Scott W. Michael.

It looked like a big, white amorphous blob at first glance, but after further investigation one could make out the mouth-end of the beast, the flukes and flippers. It was a humpback whale that had washed up on the shore of Fort Abercrombie State Historical Park, Kodiak (Alaska) about a week before we searched it out. We had heard reports that the whale had been deposited by winds and waves on the Kodiak coast, but finding the rotting blubber-laden beast was to prove a bit of a challenge. When we visited the local rangers station, they didn’t seem too eager to tell us where it was. After further probing, they finally shared the approximate location. As we left the office, a ranger mumbled “Watch out for bears.” We concluded this is why they were hesitant to share the cetacean’s resting place - they did not want to have to deal with a problems that can occur when people and food hoarding bears cross-paths.

It turns out that dead whales are a favorite of coastal brown bears in parts of coastal and insular Alaska. The tons of rotting blubber, flesh and whale organs can produce an olfactory beacon that can reach the nasal epithelium of a brown bear many miles away (there are anecdotal accounts of bears smelling putrid whale from 20 miles away). The culinary tastes of a brown bear are not that refined, and besides whale flesh has lots of nutrients that can help a bear lay down fat for the denning period. The only drawback to eating a dead whale is the flesh can be hard to handle. The skin is so tough that even a massive brown bear can have a difficult time tearing a chunk free and masticating it. (The blubber layer of a whale’s flesh can be as thick as 43 to 50 cm!)

A whale carcass can attract many bears, as was the case on the California coast centuries ago. In the book “California Grizzly” (1955) the authors share the following:

Those (ed. grizzly bears) living near the seacoast were attracted to the bonanza supply where ever a whale washed ashore – and the one-time abundance of whales in our coastal waters probably made this a not uncommon event. The first reports of bears eating this food was by the Vizcaíno party at Monterey in 1602; a very large whale had gone ashore, “ and the bears came by night to dine on it” (Wagner, 1929). Revere (1849) wrote that the carcass of a whale, thrown upon the beach, will attract a “regiment of bears” – and Kotzebue (1921) used the term countless “troops.”

On the shores of Kodiak Island and along the Katmai coast, groups of brown bears feed on moribund whales, while on the Kenai Peninsula, bears of various age classes are reported to move to Bristol Bay to scavenge on dead gray whale (Eschrichtius robustus) (Glenn and Miller, 1980). In the Yukon, grizzly bears have been observed to scavenging on Beluga (Delphinapterus leucas) carcasses. Troyer (2005) reports seeing 12 bears feeding on a gray whale carcass at the same time (there were 18 bears in the immediate vicinity). He states that all of the bears worked over the carcass, only occasionally engaging in brief altercations during the feast. Some bears would leave, only to have their place taken over by another bear. Bear continued feeding on it for a week, at which time the remains of the carcass were carried away by the tide. There are reports of observers seeing brown bears entering or appearing from a hole in a large whale carcass. Apparently, the bears entered the bloated whale to feed on the internal organs or chew at the muscle from the inside. After gorging themselves with whale flesh, brown bears may roll on the odoriferous carcass. The function of this behavior (which, unfortunately, is also a habit they share in common in domestic canines) is not known.

Brown bears occasionally capture live pinnipeds, like these harbor seals. Photo by Scott W. Michael

Not only are moribund marine mammals consumed, brown bears have actually been known to captured and kill pinnipeds. Of course, polar bears are well known form their seal-eating habits. They have developed hunting strategies and physical adaptations to effectively exploit this resource. Grizzlies, on the other hand, feed on these animal opportunistically. If a hungry bear encounters a hauled out seal that it can get to before the latter can reach the water, it may attempt to subdue it. For example, grizzlies have been known to eat harbor seals (Phoca vitulina) along the Alaskan Peninsula and in the Northwest Territories of Canada. They are more susceptible to bear attack than some other pinnipeds (e.g., sea lions) because they are much more cumbersome and would have a more difficult time escaping if they are too far from the water’s edge. Seals are also more likely to be found along sandy shorelines, where bears sometimes hunt. That said, in most cases, seals haul out on small islets along the shore – habitats that are not often visited by grizzlies. There are also rare reports of big coastal brown bears taking on walruses (this has been reported on the Kenai Peninsula) (Glenn and Miller, 1980).

(Unfortunately, it turned out we never did encounter any bears on the Fort Abercrombie humpback carcasses the day we visited it, but I would not be surprised if it was eventually located and fed upon by opportunistic brown bears.)

References:

Glenn, L. P. and L. H. Miller. 1980. Seasonal movements of an Alaska Peninsula brown bear population. Int. Conf. Bear Res. And Manage. 4:307-312.

Check out these videos of brown bears feeding on dead whales:

A mother brown bear and her offspring feed on a whale carcass in Japan. Click here.

A group of brown bears feeding on a whale carcass on coast of Kodiak Island, includes wallowing on dead cetacean (please pardon the silly commentary). Click here.

© Scott W. Michael