The brown bear is a large bear native to Eurasia and North America. Of the land carnivorans, it is rivalled in size only by its closest relative, the polar bear, which is much less variable in size and slightly bigger on average.
Grizzly bears and brown bears are the same species, although currently grizzly bears are considered to be a separate subspecies.
Brown bears are omnivorous, eating a mixed diet of plants, berries, fish, and small mammals, with almost 80 percent of their diet being tree bark, leaves, roots, mushrooms, nuts, fruit and berries. They are not averse to meat and will eat small rodents, birds, frogs or snakes, fish and carrion.
Unlike black bears, brown bears have long, strong claws that they use to dig for food, pick fruits, and catch prey.
The average life span for a wild brown bear is about 20 years, although many bears typically live longer than this. The oldest wild brown bears known lived for about 35 years.
Bear cubs are born after a gestation period of around 180-270 days. The newborn bears are naked, blind and toothless and are completely dependent on the mother. A litter usually consists of one to three cubs that weigh only 300 to 400 grammes at birth and are around 30 centimetres long.
The cubs typically stay with their mother for 2 to 3 years, learning essential survival skills. This period allows them to grow strong, learn to find food, and navigate their environment under their mother’s guidance. In some regions, like Katmai, cubs might stay with their mothers for around 2.5 years.
Cubs are born in dens and rely on their mother’s milk for nourishment and protection.
During their time with their mother, cubs learn crucial skills like foraging for food, recognizing and avoiding predators, and navigating different terrains.
While some cubs might become more independent in their second year, they often continue to den with their mother for at least one more winter.
Mothers are very protective of their cubs and may chase away or threaten other bears, including males, to keep their young safe.
By the time they are around 2 to 3 years old, cubs are generally ready to venture out on their own and start their independent lives.
They can climb trees, although their ability to do so diminishes as they grow older and larger. While young brown bears are excellent climbers, their size and weight can make it more challenging as they mature. However, they are still capable of climbing trees, even as adults.
Why do they climb trees, well for various reasons, including escaping predators, accessing food (like fruit), or even just for fun or exploration.
They have an exceptionally acute sense of smell, exceeding that of dogs. Contrary to popular belief, bears are not nearsighted. Their eyesight and hearing are comparable to humans. They can run in short bursts up to 40 mph (64 kph) and are excellent swimmers
They use rocks as a tool to scratch an itchy spot and they know when they are being hunted.
Brown bear attacks on humans are relatively rare, with an average of about 40 attacks per year globally. While most encounters with bears do not result in attacks, and the vast majority of bears are not interested in attacking humans, defensive reactions can occur if a bear feels threatened or surprised, especially if it has cubs.