Bears
...g several times. Courtship and beyond -- Female polar bears reach sexual maturity at about four years; males at about six years. Most male polar bears don't successfully mate until eight to 10 years and older. Breeding takes place in April and May on the sea ice. During the breeding season, males and females find each other by hanging out in the best seal-hunting habitats. Courtship, and times are tough -- Male polar bears have been seen following the tracks of breeding female polar bears for more than 62 miles. Competition for females is intense. There are about three adult males to every breeding female. Before mating, a female polar bear may be accompanied by several males. The males fight fiercely among themselves until the strongest or largest male succeeds in chasing the others away. Fights are rarely fatal, but do result in broken canines and scars on the head, neck, and shoulders. Dominant males may succeed in breeding several females in a season. Polar bears may have many different mates over their lifetime. The deed is done -- The total gestation period is about eight months. Once mated, females begin depositing fat in preparation for cubbing. Females need to gain at least 440 pounds for a successful pregnancy. Only pregnant female polar bears hibernate, and it's not the deep sleep of other hibernators. Pregnant females usually enter land-based dens in mid- to late October, and unlike most other hibernators, they give birth while hibernating. Cubs are born November through January in the den. Most adult females give birth once every three years. In some populations, birth occurs once every two years. The most frequent litter size is two. Babies -- Polar bear cubs are born small and helpless, with their eyes closed. They weigh 16 to 24 ounces and are about 12 inches long. Males are born slightly larger than females. During their first three or four months, the cubs nurse as often as six times a day. Although frequency decreases, some cubs nurse for as long as 30 months. They open their eyes within the first month, begin walking in the den at about two months. By the time the mother and cubs emerge from the den in late March or April, the cubs weigh 22 to 33 pounds. Mother polar bears are extremely protective of their young, even risking their own lives in their cubs' defense. Cubs remain with their mothers until they are 30 months old. Cubs begin eating solid food as soon as their mother makes her first kill on the sea ice (about three to four months of age). By eight months of age, they weigh more than 99 pounds. Mealtime -- A polar bear's stomach can hold an estimated 15 to 20 percent of its body weight and needs an average of 4.4 lbs. of fat per day to survive. Polar bears swallow most food in large chunks rather than chewing. They feed mainly on ringed seals and bearded seals. Depending upon their location, they also eat harp and hooded seals and scavenge on carcasses of beluga whales, walruses, narwhals and bowhead whales. When other food is unavailable, they'll eat reindeer, small rodents, seabirds, ducks, fish, eggs, vegetation (including kelp), berries and human garbage. Feeding on humans -- Polar bear attacks on humans occur most often at sites of human habitation, such as hunting camps, weather stations and towns. Compared to other bears, polar bears are more willing to consider humans as prey. Polar bear subadults and females with cubs attack most often. They're also the chief scavengers (among polar bears) of human dump sites. Both groups tend to be thinner and hungrier; subadults are inexperienced hunters, and females with cubs must feed themselves and their young. Lookin' good -- Body temperature, which is normally 98.6 F, is maintained through a thick layer of fur, a tough hide, and an insulating layer of blubber. Polar bears are completely furred except for the nose and footpads, which are black. A polar bear's skin is black. Its coat is about 1.2 inches thick. A dense, woolly, insulating layer of underhair is covered by a relatively thin layer of stiff, shiny, clear guard hairs. The fur is oily and water repellent and can be white, creamy yellow or brown. They completely molt (shed and replace their fur -- can you imagine the vacuuming required?) annually, in May or June. The molt can last several weeks. Excuse me, are those your feet? -- Polar bears' paws are huge compared to body size, reaching 12 inches in diameter. We're talking built-in snowshoes here. Each toe has a ...