Black bears (Ursus americanus) are present on the island of Newfoundland and in Labrador. Females can weigh up to 70 kg, males are much larger (135 kg). They are usually black although blong, brown, cinnamon and dark brown can also be observed.
Bears are omniovres, meaning they eat meat and plants. In fall, they feed extensively on berries. In spring they have been known to prey on caribou calves.
Bears are not usually a threat to humans. Most bears will run away when they see a human. Occassionally bears will scavange garbage and will become accustomed to humans. These bears can attack when threatened. For black bear safety tips follow this link.
Polar bears (Ursus maritimus) are only found along the coast of Labrador. Polar bears are one of the most dangerous land mammals. They are very large, males weigh 400-600 kg and females are about half the size of males. They are white, whith long faces, small ears, and long necks. Their main food source is seals, which they find on pack ice. They can smell a seal breathing hole when it is over a kilometre away and covered by snow and ice.
Sources: Hinterland Who's Who and A.W.F. Banfield "The Mammals of Canada"