NATURAL HISTORY

KENAI PENINSULA BROWN BEAR} Ursus arctos kenai
FAMILY: Ursidae

DESCRIPTION: Brown bears are usually dark brown in color, with shades varying from cream to black. The brown bear is characterized by a distinctive hump on the shoulders, a slightly dished profile to the face, and long straight claws on the front paws used for digging. Weight varies with the season and diet. Spring bears weigh the least, and bears quickly gain weight during the summer, in preparation for hibernation. Males generally weigh between 400 and 900 pounds when mature, but can reach 1,410 pounds. Females are half to three-quarters as heavy as males.

HABITAT: Kenai Peninsula brown bears frequent salmon streams and berry patches in the summer and fall and over-winter in mountainside dens.

RANGE: Kenai Peninsula brown bears are only found on 6.2 square miles of the 14.9-square-mile Kenai Peninsula of Alaska. During the winter the bears hibernate in mountainside dens and frequent early green-up areas in spring. During the summer bears spend more than 70 percent of their time near salmon streams and also graze on upland berry patches.

BREEDING: Female brown bears reach sexual maturity at 3.5 to seven years of age, with most cubs born to females younger than five years not surviving. Males become sexually mature at a similar age but are generally not large or dominant enough to be enter the breeding population until eight to 10 years old. Mating takes place from early May to the middle of July, but implantation does not occur until about October or November and is dependent on the female having adequate fat stores for pregnancy and lactation. The young are born from about January to March. Litter size ranges from one to four, but two is most common. Cubs remain with their mothers for at least 2.5 years. Females only breed every three years — a very long reproductive period compared to most large mammals in North America. Thus, if female brown bears are removed from a population, that population is subject to long-term decline.

LIFE CYCLE: Brown bears generally live 20–25 years, but they occasionally may live to be older than 35 years of age.

FEEDING: Diet varies with the season. In the spring Kenai bears feed on early green plants, including horsetail, skunk cabbage, grasses and sedges. They may also prey on moose, Dall sheep, caribou and mountain goats, especially on the more vulnerable young of the year. During late summer and fall, the bears feed heavily on salmon, supplemented with foraging in berry patches.

THREATS: Kenai brown bears were not known to be in decline but were protected as a state species of conservation concern from 1989–2000 due to concerns about habitat degradation and small population size. In addition to sport hunting, unsustainable human population growth is a major threat, along with accompanying issues like habitat degradation, increasing numbers of kills for defense of life and/or property, and roadkill.

POPULATION TREND: The number of Kenai brown bears was unknown prior to 2010, when the best population estimate was 582 bears. The population is thought to have been relatively stable until 2013, but the current trend is one of precipitous decline, with 125 bears known to have been killed since that year due to the long-established hunt that occurs on the peninsula, as well as other human causes. An additional 28 bears are estimated to have been killed by other human causes. It is likely at least another 16 bears will be killed fall 2014.

Kenai Peninsula brown bear photo courtesy USFWS