FWS Focus

Overview

Characteristics
Overview

The Kodiak brown bear (Ursus arctos middendorffi) is a subspecies of brown bear that only exists on the Kodiak Archipelago (Kodiak and surrounding islands Afognak, Shuyak, Raspberry, Uganik, Sitkalidak, and others) in Alaska. There are an estimated 3,500 Kodiak Brown bears on the Kodiak Archipelago and their diet and habits are similar to those of other North American brown (grizzly) bears (Ursus arctos horribilis); most bears spend just over 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 (size and shape) differences. 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 (the ability of individuals to reach different body types depending on the environment) and resource availability (e.g., 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.

Scientific Name

Ursus arctos middendorffi
Common Name
Kodiak bear
Kingdom

Location in Taxonomic Tree

Identification Numbers

TSN:

Characteristics

Characteristic category

Similar Species

Characteristics
Similar Species

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 (grizzly) bears but it can be similar in size to other coastal brown bears. 

Characteristic category

Lifecycle

Characteristics
Lifecycle

Kodiak brown bears become independent of their mother around 2-3 years old and alternate between phases of inactivity and weight loss (hibernation) and activity and weight gain each year throughout their life. Some bears on Kodiak, however, spend only short amounts of time denning or none at all.

Lifespan

Brown bears can live into their 40’s in captivity and their 30’s in the wild. Bears in their 20’s are considered old animals.

Reproduction

Brown bears reach sexual maturity around 4 years old for females and 6 years old for males. They breed in May-July while the female can have multiple bouts of estrus. Ovulation is induced but can also happen spontaneously, and multiple ovulations during estrus are possible. Both males and females often mate with many partners. Unlike humans and 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. Delayed implantation 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 (2.4 per litter on average in Kodiak) are born during hibernation about 60 days after implantation (in January-February), weigh less than a pound, and are 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 (May-June). Mothers have not eaten during the roughly six months of denning and giving birth. Cubs stay with their mother for 2-3 years before mothers drive them off to live on their own. Mothers may breed again right away or wait some time before breeding again.

Characteristic category

Behavior

Characteristics
Behavior

Brown bears are typically active during the day (diurnal), often showing a pattern of increased activity in the mornings and evenings and decreased activity midday. 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.

Characteristic category

Physical Characteristics

Characteristics
Weight

Kodiak bears and other coastal brown bears can weigh about twice as much as interior brown (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 20-40% of their body mass during hibernation, and are lightest in the spring or early summer.

Adult females are 300-700 lbs (136-318 kg)

Adult males are 600-1,400 lbs (272-635 kg)

Sound

Bears communicate primarily using body language and are therefore quiet much of the time. During conflict they are more likely to make noise; bears will sometimes “huff”—a quick exhaling of air—during a surprise encounter with a human or other bear, or to signal danger to their cubs. Jaw-popping—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 interactions. Play bouts, most common between cubs or subadults, are more likely to be silent even though they may look like fighting. Cubs vocalize cries similar to human babies if they are separated from their mothers, whine-bawl when hungry and hoping to be fed, and purr when nursing or content.  

Size & Shape

The Kodiak bear is a large bear, 3-5 feet (0.9-1.5 meters) high while on all fours and up to 10 feet (3 meters) tall when upright. They have a dished (slightly concave) face, short, round ears, a hump between their shoulders, and prominent claws (up to 6 inches in length). They are sexually dimorphic, with males being 1.2-2.2 times larger than females. The Boone and Crockett Club world-record bear is a Kodiak bear with a skull measuring 30.75 inches (78.1 cm; width + length).

Color & Pattern

Kodiak bears are varying shades of brown from light brown to dark brown. They 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 guard (outer-most) hair, and it is thickest in the fall just before hibernation.

Characteristic category

Habitat

Characteristics
Habitat

Kodiak bears are adaptable and use almost all habitat types on the Kodiak archipelago: from dense forests of Sitka spruce on the northern islands, to steep, glaciated mountains rising to 1,360 m (4,470 ft) along the central spine of Kodiak Island, to rolling hills and flat tundra on the south end of the archipelago. They are most commonly seen using seasonal resources such as 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, such as the town of Kodiak, have learned to live with bears, adapting their behavior by taking down bird feeders, securing trash, or using electric fences to protect chickens and other attractants, and they 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.

Marine

Having to do with water

Grassland

Ecosystem with large, flat areas of grasses.

Forest

Land covered by evergreen trees in cool, northern latitudes. Also called taiga.

Coastal
Tundra

Cold, treeless region in Arctic and Antarctic climates.

Cave or Karst
Lake
Mountain
Rural
Urban
River or Stream
Wetland
Characteristic category

Food

Characteristics
Food

Kodiak bears are omnivores and opportunists, eating both plant and animal matter, and consuming almost anything they can find. Diet analyses show that Kodiak bears primarily consume vegetation (e.g., sedges, forbs, berries) and salmon (approximately 64% salmon and 26% 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 bears are also known to occasionally consume marine mammals and invertebrates, birds and their eggs, rodents, and anthropogenic (human-origin) foods.

 

Geography

Characteristics
Import/Export

Kodiak brown bear hides and skulls must be sealed by the Alaska Department of Fish and Game or Alaska Wildlife Troopers. Hides, skulls, meat or other parts require a CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) permit from the U.S. Fish and Wildlife Service for ground travel through Canada or export to other countries. 

 

Range

Kodiak brown bears are only found in the Kodiak Archipelago in Alaska.

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