Grizzly Bear (Ursus arctos)


Class: Mammalia
Order: Carnivora
Family:    Ursidae
Size:    Height: 6 to 8 feet (1.8 to 2.4 m) when standing
Weight: 220 to 1150 pounds (100 to 526 kg)
Diet: Mostly vegetation, but also mammals, fish, insects and berries
Distribution: Western North America and the northern tundra
Young:  1 to 4 cubs every 3 years
Animal Predators:  None
IUCN Status: No special status
Terms: Young: Cub
Lifespan: Up to 25 years in the wild and up to 47 years in captivity



        Grizzly bears usually avoid human contact. 

        Man is the biggest threat to grizzlies.

        They can consume up to 90 pounds (40 kg) of food per day.


Grizzly bears are the second largest living carnivores in North America, second only to polar bears, and males are usually larger than females. They have brown fur that varies in shade from light beige to reddish brown to almost black. Their fur is sometimes frosted with white along the shoulders and back, giving them a grizzled appearance, which led to their being named grizzly bears. They have an excellent sense of smell and average hearing. Although it was once believed that they had poor eyesight, they can actually see colours, movement and form as well as people can. Grizzly bears are extremely powerful animals with excellent endurance. 



The home range of a grizzly can extend from 200 to 6,700 square kilometres (77 to 2,587 square miles). They can be found in many different types of habitats, including open areas such as tundra, alpine meadows and coastlines, as well as forests and mountain woodlands. 


Feeding Habits

Their eating habits depend on the season. When the salmon migrate upstream to spawn, grizzlies can be found along the riverbank, eating their fill. At other times, they will eat many different kinds of plants, berries and insects, as well as other mammals (large or small) and carrion. 



Although mating takes place in June, fertilization does not occur until fall, giving the female time to store food for herself and her cubs. Females will mate with one or more males during a two-day period. The cubs (usually two, but up to four) will be born in the safety of the motherís den, during the winter. Newborns are very tiny, weighing only one pound (0.45 kg) each and are born blind, with nearly no fur. The fathers are not involved with the mothers or children at all, and the cubs den with their mother for up to four years, after which they will leave her side and find their own den. Females can mate at the age of three but usually do not reproduce until the age of five. 



Except for during the June mating season, grizzlies prefer to remain solitary. From late summer to fall, it is imperative that these bears put on as much as 30 pounds of fat a week to carry them through the winter. When grizzlies emerge in April or May, they are severely underweight and need to find food sources immediately. The least aggressive grizzly bears are adolescents, while female grizzlies, with young, are the most aggressive. Females often have to protect their cubs from male grizzlies.  



The Mexican grizzly bear (Ursus arctos nelsoni) was assessed as extinct by the IUCN in 1996. In Canada, they are listed as of special concern by the Canadian Wildlife Service, while the prairie population was listed as extirpated in 2000, having been hunted to extermination. 



Grizzly Bear Wildlife Fact File, IM Pub, US