Brown Bear Mothers Live Near Humans to Protect Cubs

Female brown bears have come up with an interesting strategy for protecting their cubs. Recent research has shown that mother brown bears will raise their cubs near human dwellings in an effort to scare off male bears.

Male bears, also known as boars, become very aggressive during mating season. They will often kill cubs that they come across. This allows them to potentially mate with a female (also called a sow) that would otherwise be unavailable until her cubs are grown. This form of sexually selected infanticide is common among bears.

Both male and female brown bears are normally wary of humans, actively avoiding human settlements. Scientists from the Norwegian University of Life Sciences noticed something odd, though. Brown bear sows were moving to live near humans, but just for mating season. After mating season ends, they go back to avoiding people. Boars always attempt to avoid humans, even during the mating season. A brown bear mother that lives near people may have an easier time protecting her cubs since boars will be unlikely to approach the area.

The research confirmed the effectiveness of the mothers’ strategy. Brown bear sows that raised their cubs near areas that humans frequent were much more likely to raise their cubs to maturity. The researchers tracked 26 mother bears. Out of all of them, only 16 were able to successfully raise their cubs, most of them utilizing the human habitation strategy. Successful females lived an average of 2,500 feet from humans. Unsuccessful sows lived a median of about 4,000 feet away.

Brown bear mothers have learned to raise their cubs close to areas with humans, switching back to avoidance behaviors once mating season ends. This can prevent infanticide, since brown bear boars generally avoid areas with human activity. This is a form of what the authors call “fear ecology”, where an animal may move to an area it perceives as dangerous if it’ll prevent predation or other harm. It’s currently unknown if the male brown bears will change their own behavior to compensate but for now, mother bears seem to have found a useful strategy.

REFERENCE

M. J. G. Steyaert, M et al. Human shields mediate sexual conflict in a top predator. Proceedings of the Royal Society B (2016).

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