About Grizzly Bears
Learn about grizzly bears: their habitat, behaviors, physical characteristics, how to tell grizzlies apart from black bears, and information for educators.
Lewis and Clark first reported observing grizzly bear – which Clark described as “white bear” in his diary – during the fall of 1804, during their expedition across what is known today as North and South Dakota. With the help of Native Americans, who knew the majestic grizzly as “Hoh-host,” Clark correctly distinguished it from the black bear, or “Yack-kah.” The information documented in the journals of Lewis and Clark provided the first scientific data on the grizzly’s primitive range, habitat, and physical characteristics.
Grizzly bears are one of the slowest reproducing land mammals. Females do not typically reproduce until they are four or five years old. Grizzly bears mate between May and July, but the female’s body delays implantation of their eggs in the uterus until October or November. If the female has not gained enough fat over the summer to survive and raise cubs, implantation may not occur. A grizzly’s ability to garner enough quality calories through the summer is not just crucial for her survival, but also for her reproductive ability.
Mother bears rear cubs for two to three years. Males do not help raise the cubs. In fact, males can be a danger to the cubs, so females often avoid male grizzly bears while rearing their cubs.
Mating Season: Early May through mid-July
Gestation: Anywhere from 180-270 days, including delayed implantation.
Litter Size: 1-4 cubs, but average is 2-3