The Kodiak brown bear (Ursus arctos middendorffi) is a subspecies of brown bear that only exists on the Kodiak Archipelago, which includes Kodiak Island and the surrounding islands of Afognak, Shuyak, Raspberry, Uganik, Sitkalidak and others, in Alaska. There are an estimated 3,500 Kodiak brown bears on the Kodiak Archipelago, with their diet and habits being similar to those of other North American brown bears, known as grizzly bears (Ursus arctos horribilis). Most bears spend a little more than half of the year active, searching for salmon, berries or other important foods, and spend the remainder of the year denning.
The Kodiak bear is thought to have diverged from its brown bear relatives, most likely Alaska Peninsula and Kamchatka Russia populations, around 12,000 years ago after becoming geographically isolated at the end of the last ice age. Kodiak bears are thought to be unique from other Alaskan brown bear populations based on genetic and morphometric, meaning their differences in size and shape. Some research, however, suggests that genetic and size differences between Kodiak bears and other Alaskan brown bears are minimal. That research contends that phenotypic plasticity, meaning the ability of individuals to reach different body types depending on the environment, and resource availability, for example the abundance of protein-rich foods, could largely explain size differences. Still, it is apparent that genetic diversity within the Kodiak population is the lowest of any recorded North American brown bear population, and is a major conservation concern.
The Kodiak brown bear is a large bear, 3 to 5 feet (0.9 to 1.5 meters) high while on all fours and up to 10 feet (3 meters) tall when upright. They have a dished, or slightly concave face, with short, round ears, a hump between their shoulders and prominent claws that can be up to 6 inches in length. They are sexually dimorphic, with males being 1.2 to 2.2 times larger than females. The Boone and Crockett Club world-record bear is a Kodiak brown bear with a skull measuring 30.75 inches (78.1 centimeters; width + length).
Kodiak brown bears and other coastal brown bears can weigh about twice as much as interior brown bears, which are referred to as grizzly bears. Males are larger than females, and both sexes show considerable variation in weight by season. Brown bears are heaviest just before hibernation in the fall, lose 20 to 40% of their body mass during hibernation and are lightest in the spring or early summer.
MeasurementsAdult females are 300 to 700 pounds (136 to 318 kilograms)Adult males are 600 to 1,400 pounds (272 to 635 kilograms)
Kodiak brown bears are varying shades of brown from light brown to dark brown, and follow a seasonal pattern of shedding which causes their fur to look shaggy in the early summer. Their fur looks more sleek in the late summer, as they regrow their outer-most guard hair, and it is thickest in the fall just before hibernation.
Bears communicate primarily using body language and are therefore quiet much of the time. During conflict, they are more likely to make noise. During these interactions, bears will sometimes huff, which is a quick exhaling of air, during a surprise encounter with a human or other bear, or to signal danger to their cubs. Jaw-popping, which is a clacking noise that accompanies bears opening and closing their jaw in a specific way, can signal nervousness or agitation, and is sometimes used by males when following females. Growls are most common during only the most antagonistic of interactions. Play bouts, most common between cubs or subadults, are more likely to be silent, even though the behavior may look like fighting. Cubs vocalize cries, similar to human babies, if they are separated from their mothers, as well as a whine-bawl when hungry and hoping to be fed and purr when nursing or content.
Kodiak brown bears become independent of their mother around 2 to 3 years old. As they mature and throughout adulthood, bears alternate between the hibernation phase - which are defined by inactivity and weight loss - and that of activity and weight gain. Some bears on Kodiak, however, spend only short amounts of time denning or none at all.
Brown bears reach sexual maturity around 4 years old for females and 6 years old for males. They breed in May through July, while the female can have multiple bouts of estrus. Ovulation is induced, but can also happen spontaneously, with multiple ovulations during estrus being possible. Both males and females often mate with many partners. Unlike many other mammals, development of the egg stops just after fertilization and development doesn’t continue until months later, when the egg is ready to be implanted in the lining of the uterus just prior to hibernation. The process is called delayed implantation, which may provide an opportunity for the mother’s body to assess whether it can support the cost of cub production before she enters the den and does not eat for many months. In Kodiak, bears typically begin denning in early to mid-November. Cubs are born during hibernation, about 60 days after implantation occurred in January or February. The average litter has 2.4 cubs that weigh less than a pound at birth and are born unable to walk or see. Cubs from the same litter can have different fathers. Cubs develop in the den with the aid of their mother’s rich milk, and mother and cubs emerge from hibernation together in the spring, around May or June. Mothers have not eaten during the roughly six months of denning and giving birth. Cubs stay with their mother for 2 to 3 years before mothers drive them off to live on their own. Mothers may breed again right away or wait some time before breeding again.
While a 20 years of age is considered old for a Kodiak brown bear, they can live past 30 years in the wild and past 40 years in captivity.
From the dense forests of Sitka spruce on the northern islands, to steep, glaciated mountains that rise to 4,470 feet (1,360 meters) along the central spine of Kodiak Island, to rolling hills and flat tundra on the south end, Kodiak bears are adaptable and use almost all habitat types on the Kodiak Archipelago. They are most commonly seen using seasonal resources on low-elevation salt marshes in the spring and salmon streams or berry patches in the summer. Both lower-elevation salmonberry and elderberry patches, as well as berries in the alpine tundra, are important to bears. They travel along the island’s many flat open beaches patrolling for marine mammal carcasses, clams or invertebrates among the kelp.
In the winter they use dens, with the type varying by location and local conditions. At high elevations they can often be found in hillside burrows or rocky caves covered in snow, and at lower elevations they may be dug in among alder roots.
Although bears do especially well in remote wilderness areas, they are also regularly seen in the town of Kodiak and in outlying villages. Some bears become primarily nocturnal in towns to minimize their interactions with humans. Many people in urban areas, like the town of Kodiak, have learned to live with bears by taking down bird feeders, securing trash or using electric fences to protect chickens and other attractants. With these adaptations to human behavior, people enjoy opportunities to view bears in town. Still, bears are regarded as a nuisance by others, raiding dumpsters or opening car doors looking for an easy meal.
Having to do with water
Ecosystem with large, flat areas of grasses.
Land covered by evergreen trees in cool, northern latitudes. Also called taiga.
Cold, treeless region in Arctic and Antarctic climates.
Brown bears are typically active during the day, referred to as diurnal, and often show a pattern of increased activity in the mornings and evenings, with decreased activity mid-day. They will switch to nocturnal behavior in the presence of humans, however. They spend much of their time looking for and consuming food. They are not considered to be social, as they often live on their own or in mother-offspring family groups, but sociality may be common. When food resources are abundant, such as on salmon streams, localized densities of bears can be especially high and bears function within strict social hierarchies. Large males are often dominant, but females can also hold top positions.
Kodiak brown bears are omnivores and opportunists, eating both plant and animal matter, and consuming almost anything they can find. Diet analyses show that they primarily consume vegetation like sedges, forbs and berries, as well as salmon. Salmon makes up about 64% of their diet, with another 26% being plant matter. Although deer, mountain goats and elk are present on the island, they do not make up a substantial portion of the diet. Kodiak brown bears are also known to occasionally consume marine mammals and invertebrates, as well as birds and their eggs, rodents and anthropogenic, meaning human-origin foods.
The Kodiak brown bear (Ursus arctos middendorffi) is a type of brown bear (Ursus arctos) and is one of the two North American brown bear subspecies - the other being Ursus arctos horribilis. The Kodiak brown bear is larger than many inland North American brown bears, known commonly as grizzly bears, but it can be similar in size to other coastal brown bears.