The cave bear lived in Europe alongside the brown bear (Ursus arctos), to which it was closely related, and was of comparable size. Plants made up a greater part of the cave bear’s diet than of the brown bear’s. Cave bears are also thought to have spent more time in caves than brown bears, which used them mainly for hibernation.

Many cave bears died during hibernation, especially individuals that had fared poorly over the summer through inexperience, illness or old age, and so lacked the reserves to survive the winter. Skeletons of adult cave lions found deep inside cave bear dens suggest that lions sometimes ventured inside to prey on hibernating bears. Some of the lions probably also died in the attempt.

The cave bear died out around 24,000 years ago, during one of the coldest phases of the Vistulian glaciation. It is known to have been hunted by humans from time to time, which has led to the hypothesis that bears and humans competed for shelter in caves. Pressure from humans may therefore have been one of the causes of the species’ extinction.