Brain Condition Causes Bear Cubs to Become Unusually Friendly to Humans

A number of black bear cubs in California have been exhibiting unusually friendly, dog-like behavior around humans, and scientists believe a brain illness may be to blame.

Last month, California Department of Fish and Wildlife picked up a bear cub from a residential backyard. The animal had simply moved in there and didn’t seem to be intimidated by people at all. She picked up apples and ate them in front of the humans on the patio, and at one point jumped into a housekeeper’s open car trunk. This was not normal behavior for a brown bear cub, but the most concerning thing was that veterinarians in California had seen it before…

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In one case, a few years ago, a bear walked into a classroom and “sat in the back just like a puppy dog,” Ann Bryant, executive director of the nonprofit Bear League, told CBS Sacramento. In 2019, a snowboarder filmed a bear cub that got unusually close to him on a sky slope, and animal experts say that reports of such bizarre behavior can be traced back as far as 2014.

In all reported cases, the bear cubs displayed a noticeable head tilt and walked oddly. Tests showed that the bears that displayed this unusually friendly attitude behavior around humans all suffered from encephalitis, or inflammation in the brain. However, no one knows what is causing the encephalitis; five different viruses have been identified in the sick bears, but scientists have yet to prove that they are responsible for the encephalitis.


Reports of bear cubs acting strangely have become more frequent lately, with four such animals being brought to the authorities in the last year alone. Cases are becoming “more common in the Tahoe Basin and elsewhere around California.”

Unfortunately, bear cubs that display this unusual friendliness towards humans, albeit adorable to most people, cannot survive in the wild and need to be placed in the care of special facilities and zoos, or euthanized.


“Right now there are just so many unknowns about this but yet it’s out there, it’s happening,” Ann Bryant said.

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