Grizzly Bear

Ursus arctos horribilis Ord

 

 

Photo courtesy of William Keller

Description:   The grizzly bear, now extinct in Kansas, was the largest carnivore in the state. It can be distinguished by: 1) large, heavy-set body, 2) long limbs, 3) short, inconspicuous tail, 4) five claws on each foot, the claws on the front feet being nearly twice as long as on the rear and much longer than the front claws of the black bear, 5) relatively short, rounded ears, 6) concave facial profile, 7) a maned hump over the shoulders, 8) dorsal fur color varying from nearly white to yellowish- or reddish-brown, darkening to brownish-black along the midline of the back, 9) dark brown fur on its belly, legs, and ears, and 10) hair on the upper body usually being tipped white, creating a frosted or grizzled appearance, hence the common name.

Size:   Adults may attain the following dimensions: total length 1700-2300 mm; tail 60-150 mm; hind foot 225-280 mm; ear 80-135 mm; weight 250-350 kilograms.

Range and Habitat:   The grizzly bear probably ranged throughout Kansas. No specimens have survived, however, and literature records are the only documentation for this species in the state. Grizzly bears were reported from Gove, Logan, and Morris counties, and this suggests that they may have concentrated along rivers, stream courses and nearby ridges.

Reproduction:   The grizzly bear breeds from early June to late August, with a peak in mid-July. Females may breed with more than one male during the breeding season. Following fertilization, the embryos grow briefly, then cease development. They implant in the uterine lining after the female enters the winter den in late fall or early winter and continue development. After a gestation period of six or more months, one to four (average two) cubs are born in January or February, weigh about 700 grams, and are 200 to 300- mm; long. They are born blind, with their ears closed and are covered with a coat of fine gray fur. Their eyes open in about 30 days. They leave the winter den with the female in late April when they are three months old and weigh five to seven kilograms. They remain with the female throughout their first year, denning with her during the winter. The cubs usually remain with the female an additional year, again overwintering in her den. The cubs and the female gradually disassociate the following spring, and the female will frequently breed in the summer. The cubs may continue to remain together for some time in the female's home range. Young male grizzly bears may breed between their fourth and seventh year. Females reach sexual maturity between their fourth and ninth year.

Habits:   Grizzly bears primarily are active at night and during the early morning and late afternoon. Activity is greatly reduced during the midmorning and early afternoon. While inactive they usually seek windfalls or thickets and excavate a shallow depression in the soil which serves as a bed.

  Adult male grizzly bears utilize a much large (180 square kilometers) home range than adult females (54 square kilometers). and adults tend to have larger ranges than young animals. Females with newborn young seem to utilize smaller ranges, and select areas where other bears are rare. The ranges of grizzly bears frequently overlap, and there is little evidence to suggest that they maintain a defended territory. Rather, they maintain a critical minimal distance with other bears, becoming aggressive only if this distance is violated. Dispersing individuals are reported to move for over 140 kilometers searching for a home range, but once this is established, they rarely move from the area. Population densities of this mammal in areas other than Kansas are reported to vary from one bear per 11 square kilometers to one bear per 16 square kilometers.

  During late summer and autumn grizzly bears gain weight as body fat accumulates. In mid-autumn they begin to excavate a winter den, usually on a north-facing slope beneath a large tree. The den may take a week to construct and may be one and a half to three meters in length. The bed chamber may be lined with conifer branches, grasses, or leaves. They most frequently enter their dens during as snowstorm, and remain dormant until late March or April.

Food:   Grizzly bears are omnivorous, and their diet changes with seasonal availability of food items. They consume more animal food than do black bears Known items in the diet of grizzly bears include bison, deer, wapiti, ground squirrels, carrion, plant shoots, roots, and berries.

Remarks:   The grizzly bear was probably extirpated in Kansas by the middle 1800's. Its original abundance in Kansas sis unknown, but it was reported to have been common, and to have depended heavily on the great herds of bison for food. The grizzly bear's reputation for aggression towards humans tends to be exaggerated. It usually avoids human contact, but if confronted unexpectedly or when with cubs it can be highly aggressive. Grizzly bears may live 25 to 26 years in the wild, and up to forty years in captivity.


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