Brown Bears Are Seriously Active Hunters And Feast On Caribou Calves


Primed and ready to take down a cute little caribou calf. Pam Link/Flickr CC BY-NC 2.0

Ambling through the forest and shuffling across the tundra, brown bears don’t exactly give off the image of an active predator like a wolf or cougar. But new data captured on cameras hung around their necks has revealed them to be bloodthirsty calf-killing machines. Sometimes

Traditionally it is very difficult to fully observe bears over a long period of time, and often only gives results on a population level. For the most part this means that researchers only get a snapshot view of what they bear is doing at any one point in time. Coupled with the fact that relatively speaking, they spend only a very short amount of time actually hunting, it gives a limited picture of what it is they are consuming.


Attaching GPS collars to wild animals is not common practice among wildlife biologists, but can give some really fascinating insights into what creatures in the wild get up to away from the prying eye of researchers. The Alaska Department of Fish and Game decided to try and step this up a level. Over a period of three years, during the caribou and moose calving season, they fitted 17 wild bears with not only GPS trackers but also camera collars, and published their results in the Wildlife Society Bulletin

Filming short 10-second clips every 5 to 15 minutes, the cameras gave the researchers an astonishingly intimate view into what the bears were getting up to in the wilds of the Alaska bush, from swimming in rivers to mating. But what they really wanted to know was what, exactly, they were feeding on. And it turns out that the bears are far more predatory than they ever imagined.

While the ursine creatures still spent the vast majority of their time resting (60.5 percent) or traveling (21.3 percent), they spent 6.2 percent of their time feeding. By reviewing over 100 hours of camera footage, the researchers were mostly able to deduce what the bears were eating, and whether or not they had killed the prey in the first place, by identifying how fresh it was. And it seems that they are truly prolific hunters.

Over the period studied, they found that the bears were eating a wide range of foods from ptarmigans to swans, and even other bears. But most of their diet was coming from moose and caribou calves, which impressively accounted for over half of what they were eating (52.2 percent). Over a period 45 days, they estimate that the bears were killing on average 34.4 calves. This is far higher than anyone had previously imagined.


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