Interesting Brain Disease makes California Bears as Friendly as Dogs

Interesting Brain Disease makes California Bears as Friendly as Dogs

For anyone who once cherished a teddy bear, the concept of amicable bears in reality might evoke a sense of enchantment. However, a disconcerting trend has been observed in California as black bears exhibit dog-like behavior towards humans. Despite their seemingly friendly demeanor, scientists are issuing a stern warning against approaching these bears, as much remains shrouded in mystery about the underlying disease.

The Odd Behavior

The disquieting behavior initially caught the attention of the California Department of Fish and Wildlife (CDFW) in 2014. Reports from the Nevada Department of Wildlife highlighted encounters with young California bears in the Tahoe Basin displaying neurological irregularities. Extensive investigation revealed that these bears were afflicted by encephalitis, an inflammation of the brain. Curiously, the examination also unveiled five novel viruses in the affected bears, though their role in the illness remains uncertain.

The Unusual Transformation

Traditionally, bears are known for their timid nature around humans, typically avoiding interaction unless driven by the pursuit of food. However, the impacted California bears exhibit an uncharacteristic friendliness and fearlessness. Astonishingly, they remain unfazed by clapping or shooing. As the disease progresses, lethargy, substantial weight loss, head tilting, tremors, and an abnormal gait become evident.

Bizarre Encounters with California Bears with Brain Disease

One bear that gained attention was spotted in 2019 at the Northstar ski resort. The bear, captured in a video, was observed sniffing a person’s glove and even stepping onto their snowboard. In February 2021, another affected bear made its way into a residential area in Pollock Pines, California. Despite its lethargic state, the bear didn’t display fear towards people. Locals began feeding the bear, leading to interactions against CDFW guidelines. Astonishingly, the bear even crawled into a car trunk and allowed people to pet it.

Wildlife Guidelines and Concerns

Flag of California
Flag of California

The CDFW strongly discourages such interactions between humans and wild animals like bears. With the encephalitis’s elusive cause, the potential health risks these California bears might pose to other animals are unknown. Upon examination, the bear from Pollock Pines displayed physical and mental anomalies, leading to its eventual euthanization. The CDFW’s preliminary findings linked the bear’s condition to encephalitis, making her the third bear with neurological disorders that the CDFW laboratory had encountered in a year.

The Mysterious Illness of the California Bears

Efforts to comprehend the underlying cause of the bears’ perplexing illness are ongoing. The newfound viruses have been found to impact not only the bears’ brains but also their liver and spleen. Strikingly, the disease shares some similarities with chronic wasting disease, also known as “zombie disease,” observed in deer, elk, and moose. Just like bears with encephalitis, animals with “zombie disease” experience weight loss, listlessness, drooling, lack of awareness, lack of fear, and eventually, death.

Human Threat or Not?

While diseases can sometimes leap from animals to humans, a veterinarian from UC Davis, Jamie Sherman, opines that the viruses detected in the bears are not typically known to affect humans. Regardless, given the substantial gaps in our understanding of the disease, scientists advise exercising caution when encountering these unusually friendly bears.


In the realm of California’s black bears, a peculiar and unsettling disease has altered their behavior, rendering them oddly friendly and fearless towards humans. Despite the ambiguity surrounding the illness, scientists are striving to decipher its origins. With the enigmatic nature of the affliction, people are encouraged to be vigilant and avoid potentially risky interactions with these atypical bears.

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