Grizzly Bear Biology: What's Under All That Fur?

Physical Appearance      Paws, Claws & Tracks      Size      Skulls & Humps      Bear Senses        Bear Abilities        Life Cycle


Life Cycle Of The Grizzly Bear


    Grizzly bears have a low reproductive rate 

  •  Reproduction 

    • Mating Season 

      • Grizzly Bears in British Columbia generally mate between 
        May and mid-July 

    • First Pregnancy 

      • Female grizzlies usually are first able to produce cubs between 4 ½ and 10 years of age 

    • Frequency of Litters 

      • Female Grizzly Bears breed every 3 to 4 years, but it may be longer between litters in locations without a good food supply or in a harsh environment 

      • Because most do not breed beyond age 20, female grizzlies will bear no more than four or five litters in a lifetime 

Source: Grizzly Bears In BC
  •  Offspring 

    • Birth 

      • Cubs are usually born between the end of January and early March, during hibernation 

      • While still in a dormant state, the Grizzly mother gives birth and cares for her nearly hairless cubs 

    • Number of Cubs 

      • The average litter size is two, but can range as high as four 

      • The number of cubs in a litter depends upon the female’s body weight 

    • Birth Weight & Length 

      • Cubs are about 15-20 cm long and weigh slightly more than 225 g - 400 g 

    • Growth of Cubs 

      • Cubs weigh less than 400 g when born, but they gain weight very fast due to the high fat content of their mother's milk (about 33% fat) 

      • When they leave the den in the spring they weigh about 8 kg and continue gaining weight rapidly in the summer and enter the winter den around 45 kg (100 lb.) 

      • They can weigh as much as 60 kg at the end of their first year... Bear Biology  

Source: WebShots

Family Ties 

The Grizzly mother continues to nurse them until late fall 
as she teaches them to climb trees in reaction to danger, swim and

forage and hunt for food 

At the end of the cubs' second winter, 
the mother sends them out to fend for themselves and 
establish their own territories... Natural History Museum 

Grizzly mothers form deep bonds with their cubs, fiercely protecting them 
from adult males and other predators, until they are two years old  

In June of the third year, adult females usually breed again,
 and they chase the cubs who are now quite large, off to become self-sufficient 

 Life Span 

Grizzly Bears reach sexual maturity between 4 and 5 years 
and are considered fully grown by 8 to 10 years of age

Bears in the wild can live up to 25 years

 Source:  Bears In BC - Hinterland - BC Government - Grizzly Bears In BC

Check out more ...Grizzly/Brown Bear Facts 
Grizzly Bear Index
Grizzly Bear Introduction
What Colour Are They?
What's Under All That Fur?
Grizzly Bears In Action
Grizzly Bear Activities
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