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suggested that this indicates bears are still in the process of evolving from a carnivorous to a predominantly herbivorous diet. Polar bears appear to have secondarily re-evolved fully functional carnassials, as their diet has switched back towards carnivory. The dental formula for living bears is: The bears are mostly found in the northern hemisphere, with a single species, the Andean Bear, occurring in South America. The Atlas Bear, a subspecies of the Brown Bear, was the only bear native to Africa. It was distributed in North Africa from Morocco to Libya, but has been extinct since around the 1870s. All the other species are found in North America, Asia and Europe. The most widespread species is the Brown Bear, which occurs from Western Europe eastwards through Asia to the western areas of North America. The American Black Bear is restricted to North America, and the Polar bear is restricted to the Arctic Sea. All the remaining species are Asian. With the exception of the Polar Bear the bears are mostly forest species. Some species, particularly the Brown Bear, may inhabit or seasonally use other areas such as alpine scrub or tundra. While many people think that bears are nocturnal, they are in fact generally diurnal, active for the most part during the day. The belief that they are nocturnal apparently comes from the habits of bears that live near humans which engage in some activities, such as raiding trash cans or crops, are nocturnal in order to avoid humans. The sloth bear of Asia is the most nocturnal of the bears, but this varies by individual and females with cubs are often diurnal in order to avoid competition with males and nocturnal predators. Bears are overwhelmingly solitary and are considered to be the most asocial of all the Carnivora. Liaisons between breeding bears are brief, and the only times bears are encountered in small groups are mothers with young or occasional seasonal bounties of rich food (such as salmon runs).
Distribution and habitat
Behaviour
Bears produce a variety of vocalizations such as: Their carnivorous reputation non-withstanding, most bears have adopted a diet of more plant than animal matter and are completely opportunistic omnivores. Some bears will climb trees in order to obtain mast (edible vegatative or reproductive parts such as acorns), smaller species which are more able to climb include a greater amount of this in their diet. Such masts can be very important to the diet of these species, and mast failures may result
Vocalizations
* Barking: produced during times of alarm, excitement or to give away the animal's position.
* Huffing: made during courtship or between mother and cubs to warn of danger.
* Growling: produced as strong warnings to potential threats or in anger.
* Roaring: used much for the same reasons as growls and also to proclaim territory and for intimidation.
Diet and interspecific interactions