Grizzly Bear

grizzly bear
The grizzly bear is a subspecies of the brown bear family growing to 6-7 feet long and 400-600 pounds.

A subspecies of the brown bear family, the grizzly bear is one of the worlds largest land predators. Growing to an average of 6 to 7 feet in length and weighing between 400 and 600 pounds. Some larger male grizzlies can reach as much as 800 pounds or more. Despite this size, adult grizzly bears can reach speeds of 40 mph. Coloring of the grizzly bear can range from blonde, to deep hues of brown, or red. The most distinguishing characteristic of the grizzly is a large hump, located above the front shoulder. This powerful muscle mass is used to power the forelimbs while the bear digs. Powerful hind legs allow the bear to stand completely erect at times, giving a better view of the surroundings or reaching for food.

Home range of the Grizzly Bear

Currently grizzly bears in North America can only be found in about 1% of their original home range. Most commonly found in western Canada and Alaska, grizzly bear ranges include (in smaller numbers), Idaho, Montana, Washington, and Wyoming. Recent sightings have been documented as far south as Colorado and possibly northern California.

Grizzly bear by the numbers

Today, the grizzly bear population hovers at around 60,000 in North America with the greatest populations into Canada. A legally protected animal, the grizzly bear is expected to repopulate much of its former range. This process will be slow however, due to the human ramifications and the bear's slow reproductive habits. Grizzly bears evoke a great deal of time into raising their young.

Grizzly bear behavior

Unlike some bear species, grizzly bears lead a much more solitary life, except when breeding, cub rearing, or near an abundant food supply. Preparing for winter, these bears will gain tremendous amounts of body fat, before going into false hibernation. Unlike other bear species, grizzlies may not hibernate at all if ample food supplies are found throughout the winter months. Hibernating in dens typically at elevations of 6,000 feet or more, grizzly bears are known to still move around on occasion and even partially "recycle" their own body wastes.

Typically when grizzlies do hibernate it can be for periods of 5 to 8 months at a time, depending on the winter. It is at this time female bears will give birth to their young. These cubs, which are less than 1 pound at birth, must be nursed by the mother while in the den. When spring arrives these cubs should weigh about 20 pounds.

Unlike other North American bear species, as grizzly bears emerge from their dens in spring they will actively seek out prey such as young deer or elk calves. Where human populations are present, sometimes livestock can be targeted.

Grizzly Bear Reproduction

Female grizzly bears reach breeding maturity at 3 or 5 years of age and can breed about every 2 years. Male bears reach sexual maturity at about the same age, but may not win breeding rights because of size. Similar to most mammals, bears often fight for breeding rights to be accepted by females.

During the mid summer months of June and July, female grizzlies come into their estrous cycle, usually lasting 3 weeks. During this time it is not uncommon for a single female to be mated by more than one male. With a gestation period of around 220 days, typically female bears give birth to small liters of 1 to 3. The cubs weigh in at less than 1 pound, often no bigger than a chipmunk. Although completely helpless at birth, the cubs are strong enough to suckle on their mothers fatty milk. The cubs will wean of their mothers from birth through September or October of their first year, staying with their mothers until the following summer when they reach about 1 1/2 in age. It is at this time the female will go into estrous again.

Grizzly bear cub survival is completely dependant on the mother. She must show them how to forage, how to kill, where they must den, and where to hide in case of danger. Like most young bears, grizzly bear mortality rates are often high.

Grizzly bear Diet

Although grizzly bears can be extremely proficient predators, their diets consist of mainly of berries, roots, nuts, flowers, grasses, and other vegetation. The claws of all bears in general have adapted to digging up such food sources. At certain times of the year, these Omnivores, prey on fish, small or young mammals, carrion, and even black bears. Opportunistic hunters, grizzly bear aggression during periods of hunger can lead them into conflict with other species, including wolves and humans.

Diets of grizzly bears are generally high in carbohydrates, consequently lower in protein and fats. However these bears generally prefer foods containing higher proteins and fats such as fish. Grizzly bears who do diet on higher protein foods along inter-coastal regions are often much larger than their interior cousins. As grizzly bears emerge in spring from their winter dens, they tend to continue to loose weight with food scarcity. However, unlike black bears, grizzlies will quickly become predators and hunt with much more aggression. With summer, and the many diverse food groups that will flourish in bear ranges, recovery from the energy and fat loss from the previous year is important to their survival. Grizzly bears will begin accumulating large fat reserves again as fall approaches, primarily from fish, insects, fruits, and roots.

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