Brown bears found inland and in mountainous habitats are called "grizzlies" while brown bears living in coastal areas are called Coastal Brown Bears. The Kodiak brown bear is isolated to Kodiak Island in Alaska. Kodiak bears are not Grizzly Bears, the name “grizzly” comes from the silver tipped hairs these bears get, as they grow older. In comparison, the grizzly is considerably smaller than both the coastal brown bear and the Kodiak brown bear. This size difference is due to the abundance of food available in coastal areas and on Kodiak Island. The Kodiak bear has been isolated to Kodiak Island for some 12,000 years. The bone structure of the Kodiak is much larger than other Brown Bears, they have a more diverse social structure than other bears due to the close proximity in which they live and they have a gene pool that is much smaller than that of other bears.
The Kodiak brown bear is the world’s largest bear while the polar bear being a direct descendent of the brown bear is the world’s heaviest bear. Polar bears have been reclassified as marine mammals due to the amount of time these bears spend in the water.
The bear pictured is a Coastal Brown bear photographed at Hallo Bay in Katmai National Park in Alaska. This is a she bear or sow, (terms often used in reference to a female bear) with her cub. Male bears are called boars and female bears are called sows.
Brown bears gain an average of 3-6 pounds of fat per day during peak periods to obtain enough body weight to survive winter hibernation. Hibernation is a state of dormancy at which time bears are inactive, allowing them to adapt to short winter food supplies. During a bears hibernation, its body temperature is close to that of the surrounding air, its metabolic rate is comparatively high and it may awaken and move about outside the den. The length of a bears hibernation depends on climate, location, sex, age and reproductive status of the individual bear. Bears that have not obtained an adequate fat reserve may not hibernate at all.
Mating takes place during the spring months from late May through early July. Brown bears are serially monogamous and will remain with the same mate from several days to a couple of weeks. Female brown bears become sexually mature between 5 and 7 years of age, males usually will not mate until a few years later when they are able to compete successfully with other males for an available female.
Through a remarkable process known as delayed implantation, a fertilized egg will divide and float free within the uterus for six months. During hibernation, the embryo will attach itself to the uterine wall and the cubs will be born after an eight-week period while the mother sleeps (January or February). This process is important to the survival of the mother. Should she not gain enough weight to carry her through the winter, the embryo will not implant and be reabsorbed by the body.
The average number of cubs born is between one and four, with two being the average. There have been cases where a bear has been spotted with five cubs, though the mother has been suspected of adopting an orphan, which is not unusual. Age, geographic location and food supply influence the size of a bears litter. The number of cubs a female will have increases, as she gets older. At birth, the cubs are blind, toothless, hairless and very tiny weighing less than 1 pound. They feed on mother’s milk until spring, when she is ready to leave the den, sometime between April and May and as late as June depending on climate conditions. At this time they will have developed enough to follow her and begin to forage. The cubs will weigh from 15 to 20 pounds at this time.
Cubs will stay with their mother from two to four years. During this time, they will learn survival techniques crucial to their existence. They will learn which foods return the highest nutritional values, where to attain them, how to hunt, how to fish, how to defend themselves and where to den. The cubs learn by following and imitating their mother’s actions during the period they are with her.