Mating takes place from early May to the middle of July but implantation does not occur until about October or November. The young are born from about January to March. The litter size ranges from one to four, but two is most common. Cubs remain with their mothers usually for at least two-and-a-half years, so the most frequently a female can breed is every three years.
In some areas, such as near the Arctic coast, the breeding interval is considerably longer. Longevity in the wild is 20 to 25 years although rarely animals in excess of 35 years of age have been reported.
Under most circumstances, brown bears live as lone individuals, except for females accompanied by their cubs. During the breeding season, a male may attend a female for up to two weeks for mating.
Brown bears are distributed in overlapping home ranges and male home ranges are larger than those occupied by females. Despite their propensity for a solitary existence, brown bears congregate at high densities where food is abundant, such as at salmon streams or garbage dumps. In such circumstances, adult males are the most dominant individuals.
Brown bears mainly eat vegetation such as grasses, sedges, bulbs, and roots. Adult males weigh between 60 and pounds kg. Sun bears are the least studied of all bears. They are excellent climbers, and their diet is thought to consist of small mammals, birds, palm tree tips, and fruits. Range: The sun bear is the only species to occupy the lowland tropical rainforests of Southeast Asia.
Its range is shrinking due to habitat loss, but it has been found throughout the region, from Bangladesh to Vietnam to the Indonesian Islands. Large-scale deforestation that has occurred throughout Southeast Asia over the past three decades has dramatically reduced suitable habitat for this species.
Sun bears are also harvested for their gallbladders and are traded as pets. Description: Long, curved claws and a coat that is long, straight, and shaggy give this species a unique and somewhat disheveled appearance.
Their mobile snouts and lips and gapped teeth are adapted for sucking up termites and ants, their primary food sources. They may also eat various kinds of vegetation, especially fruits in season. While American and Asiatic black bears will usually flee or climb a tree when threatened, a sloth bear is more likely to stand its ground.
Range: Sloth bears are predominantly found in the lowland forests of India and Sri Lanka. It is thought that they prefer rocky areas and drier climates. As is the case with other bear species in Asia, sloth bears are threatened by habitat loss and gallbladder harvesting. Since these bears can be particularly dangerous when provoked, it has been difficult to garner public support on their behalf.
Adult females weigh between and pounds kg. A spectacled bear spends even more time in trees than does the American black bear. This bear has the most varied diet of all the bears, eating dozens of species of vegetation including bromeliads and cactus.
They will also eat young calves. Range: The spectacled bear is the only bear species found in South America. It inhabits a wide range of habitats, from dense rainforest to coastal scrub desert. They are found as far north as Venezuela and as far south as Bolivia. The fate of spectacled bears is linked to their role in various forms of Andean mythology. In some cultures, the bear is revered as a god, while in others it is regarded as evil and often destroyed.
Blood and bones are consumed by many people for strength and virility. There is some debate over the number of subspecies, but brown bears share similar characteristics: a massive build, a dish-shaped face, and a hump above the shoulders. Adult females weigh from to pounds kg. Diet and weight varies depending on the habitat; some have remained primarily herbivorous while others have become predators of moose, caribou, and elk.
The heaviest brown bears are the coastal dwellers that feast on salmon along the west coast of Alaska and British Columbia. The National Wildlife Federation has a program on National Forest lands surrounding Yellowstone Park to prevent attacks on domestic livestock by purchasing the grazing allotments from ranchers.
Grizzly bears use sounds, movement, and smells to communicate. They growl, moan, or grunt, especially when females are communicating with their young or during mating season when male bears can fight each other fiercely for the opportunity to mate with receptive females. Grizzly bears also rub their bodies on trees to scratch and to let other bears know they are there. Winter can be very tough for many species of wildlife, because the season brings harsh weather and little food.
Grizzly bears hibernate in warm dens during the winter to minimize energy expenditure at a time when natural foods are not available and to permit their tiny young to be born in a warm and secure environment. Throughout the summer and autumn, grizzly bears build up fat reserves by consuming as much food as they can find.
In late fall or winter, the bears find a hillside and dig a hole to serve as their winter den. When inside the den, grizzly bears slow down their heart rate, reduce their temperature and metabolic activity, and live off stored fat reserves. Pregnant females give birth in the dens and nurse their cubs until they are large enough to venture outside in the spring as snow melts and new food become available.
Depending on the length of the winter season, grizzly bears can stay in their dens for up to seven months. Grizzly bear hibernation is not as deep of a sleep as some other hibernators, like bats or ground squirrels, and they will quickly wake up when disturbed. Females with newborn cubs are the last to leave their dens in the spring.
Females with older cubs emerge earlier and solitary females and males are the first to exit dens in the spring. Pregnant females are the first to enter dens in the fall followed by females with cubs; solitary males enter dens the latest.
Grizzly bears begin to look for mates in the spring and early summer. Females can mate with more than one male during her breeding season. If a female bear is unable to gain enough weight during the summer and fall, her body will tell her to not proceed with the pregnancy and the embryo will reabsorb. This gives her a head start on gaining enough weight to have a successful pregnancy the following year.
When female grizzly bears enter hibernation, the embryo implants in her uterus and begins gestation. In January or February, female grizzly bears give birth to one to four cubs usually two. The female will care for her young inside the den until spring, when they finally step out into the world. The mother cares for her young for at least two more years, feeding and protecting them.
When the cubs are two and a half years old, they typically separate from their mother. In areas with little food, the cubs may stay with their mother longer. Typically separation happens when the female enters breeding condition and attracts males, which can be a threat to the cubs. At around five years of age, grizzly bears reach sexual maturity. Grizzly bears are mainly solitary and territorial, except for mothers and their cubs, or when a plentiful food source is discovered.
Grizzly bears are known to congregate at rivers with many fish and at improperly fenced garbage dumps. Grizzlies can run pretty fast, reaching speeds as fast as 35 miles an hour for very short sprints.
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