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Brown Bear (Ursus arctos)

Kodiak Bear Fact Sheet

  • Kodiak bears are a unique subspecies of the brown or grizzly bear (Ursus arctos middendorffi). They live exclusively on the islands in the Kodiak Archipelago and have been isolated from other bears for about 12,000 years.
  • Kodiak brown bearThere are about 3,500 Kodiak bears; a density of about 0.7 bears per square mile.
  • Kodiak bear populations are healthy and productive. They enjoy relatively pristine habitat and well managed fish populations. In most areas the number of bears is stable, but there are some places where bear density is increasing.
  • Male bears are called boars, females are sows, and youngsters are cubs.
  • Kodiak bears are the largest bears in the world. A large male can stand over 10' tall when on his hind legs, and 5' when on all four legs. They weigh up to 1,500 pounds. Females are about 20% smaller, and 30% lighter than males.
  • The oldest known wild Kodiak bear was a 34-year-old sow. The oldest boar was 27.
  • Cubs are born in the den during January or February. Weighing less than a pound at birth with little hair and closed eyes, they suckle for several months, emerging from the den in May or June, weighing 15-20 pounds.
  • Typical litter sizes are 2-3 cubs. Sows are sometimes seen with 5 or 6 cubs in tow, probably due to adopting cubs from other litters.
  • Kodiak BearMost cubs stay with their mothers for 3 years. Over 25% of the cubs die before they leave, with cannibalism by adult males being one of the major causes of death.
  • Bears that have recently left their mothers, at ages 3-5, have a high mortality rate as they face the world on their own. Some of these subadults are the “juvenile delinquents” of bear society and are also the ones most likely to cause problems with people.
  • Kodiak bears become sexually mature at age 5 and can continue to produce cubs throughout their lives. The average interval between litters is about 4 years.
  • Kodiak bears begin entering their dens in late October. Pregnant sows are the first to go to dens, males are the last. Males begin emerging from their dens in early April, while sows with new cubs may stay in dens until late June. Some males may forego denning, staying awake all winter.
  • Researchers from NASA and the medical professions are very interested in denning physiology. They are trying to figure out how bears can sleep for up to 8 months without eating, drinking, urinating or defecating, yet when they awaken they have lost little bone mass or muscle tone and have no signs of uremia. Understanding this could help astronauts during extended space flights or patients who are bedridden.
  • Though Kodiak bears are often touted as the world's largest land carnivore (meat eaters), they are really omnivores (using a variety of foods). They actually spend more time eating grass, plants and berries than meat. Fish are an important part of their diets, but few Kodiak bears expend the time or effort necessary to chase and kill mammals.
  • Kodiak brown bears swimmingBears use the most nutritious parts of their food to maximize their weight gain. Grass and forbs are only used while they are rapidly growing in the spring and early summer. Brains, flesh and eggs are preferred parts of the salmon. Internal organs of deer, elk and cattle are eaten first when one is killed or scavenged. Berries are used most often when they are ripe and sugars are at their highest level.
  • Bears are naturally diurnal (active during the day), but when faced with competition for food or space, they adopt a more nocturnal (active at night) life style.
  • Bears do not defend territories, but they do have traditional areas that they use each year (home ranges). Because of the rich variety of foods available on Kodiak, bears here have some of the smallest home ranges of any brown bear population.
  • Mating season for Kodiak bears is during May and June. They are serially monogamous (having one partner at a time), staying together for a couple days or a couple weeks. As soon as the egg is fertilized and divides a few times, it enters a state of suspended animation until autumn when it finally implants on the uterine wall and begins to grow again.
  • Although generally solitary in nature, Kodiak bears often occur in large groups in concentrated feeding areas. Because of this, they have developed a complex language and social structure to express their feelings and avoid fights.
  • Traditionally, Kodiak Natives (Alutiiqs) hunted bears for food, clothing and tools. Arrows, spears, and a great deal of courage were required hunting equipment. Bear heads were usually left in the field as a sign of respect to the spirit of the bears.
  • Kodiak bears were commercially hunted throughout the 1800s with the price paid for a bear hide being comparable to that paid for a beaver or river otter pelt (about $10).
  • Three bear cubsBears and cattle ranchers have waged an ongoing battle for the past 200 years. Original Russian settlers were encouraged to bring large aggressive dogs to protect cattle from bears. As early as the 1930s, biologists and ranchers were exploring ways to reduce the number of cattle killed by bears. At one point bears were shot from airplanes, and a 9-foot high bear fence was proposed to bisect Kodiak Island and create a “bear-free zone.” All active efforts at bear control in Kodiak ended in the mid-1960s.
  • Concern over reduced bear populations prompted sportsmen to petition the Federal government to protect bears and their habitat on Kodiak. The results of their efforts were stricter regulations and creation of Kodiak National Wildlife Refuge in 1941.
  • Today hunters kill about 180 Kodiak bears each year under tightly controlled regulations. About 5,000 resident hunters apply each year for a chance at the 496 bear permits that are available for them. Hunters who are not residents of Alaska must hire a professional guide, paying $10,000 – $21,000 per hunt. Over 70% of the Kodiak bears killed by hunters are males. See Hunting Kodiak Brown Bears.
  • Range of Kodiak BearOnly one person has been killed by a bear on Kodiak in the past 75 years. About once every other year a bear injures a person.
  • Kodiak bear research, management and habitat protection is done cooperatively by the Alaska Department of Fish & Game and Kodiak National Wildlife Refuge.

Written by: Larry Van Daele
Kodiak Area Wildlife Biologist

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