Bears are generally thought of as strictly anti-social, solitary animals, but this is not correct. Habitat impediments, such as range size, prevent bears from interacting with each other very often in the wild. When they do meet competition for food or a mate can result in an encounter that is rather hostile. However, when competition for food or a mate is absent, bears have been known to strike up friendly relationships with each other and have even been observed playing together for long periods of time. This play typically takes the form of wrestling matches. Such play behaviour is often interpreted as aggression when it’s just two bears deciding to have some fun.
It’s true that bears do not live in herds or packs, but they can and do co-exist in close proximity to each other where food sources are plentiful and their numbers high. They will share home ranges with other bears by establishing a social hierarchy based on size, age and disposition. A bear will establish and maintain its place in the hierarchy by posturing or acting aggressively. In most cases these exhibitions of aggression do not escalate to a full-fledged altercation against another individual with the less dominant bear eventually backing down.
To go from living solitary to living social shows the ability of the bear to adapt its behaviour based on changes to its environment.
Contrary to popular belief, the solitary bear is not SO solitary.