Grizzly Bear

Genus: Ursus
Species: arctos horriblis

Is it a brown bear or a grizzly bear? Often, the two names are used interchangeably and it leads to a lot of confusion. Here’s the grizzly bear rule of thumb: All grizzly bears are brown bears, but not all brown bears are grizzly bears. Got it?

Grizzly bears are a subspecies of brown bears (Ursus arctos). A subspecies is a population of a species with unique physical, social, or genetic traits that distinguish it from the species as a whole.

Grizzly bears are unique, because they prefer warmer climates and interior habitat. Whereas most brown bears are found in very cold climates near coastlines in places like Alaska and northern Canada, the grizzly subspecies lives in southern Canada, the Pacific Northwest and the Rocky Mountains. They prefer fishing along rivers.

Grizzlies were excessively overhunted and now there are less than 1,500 grizzlies left in the continental United States. The National Wildlife Federation is working with the government and other conservation organizations to fight for grizzly bears and bring them back to the Pacific Northwest.

Description: Grizzly bears are large, brownish bears. They have black noses and short, rounded ears. One of the most noticeable characteristics of the grizzly bear is the hump on its back. The hump is a mass of muscles that give the bear additional strength for running and digging.

Grizzly bears received their name, because their brown fur can be tipped with white. This gives them a “grizzled” look.

Size: Grizzly bears weigh upwards of 700 pounds. The males are heavier than the females.

Diet: Grizzly bears are omnivores. Their diet consists of both plant and animal food. The most commonly eaten plants are nuts, fruits, grasses, fungi, moss and roots. If grizzly bears are on the hunt, their prey can include fish, insects, mountain sheep, elk, and rodents.

Typical Lifespan: Grizzly bears live about 25 years in the wild.

Habitat: Grizzly bears can be found in woodlands, forests, alpine meadows, valleys and near rivers and streams.

Range: Grizzly bears once roamed throughout the Rocky Mountains and Great Plains. Hunting extirpated them from the Great Plains and almost all of the Rocky Mountain states. Today, grizzly bears can be found in select areas of Montana, Idaho, Wyoming and Washington, such as Yellowstone National Park and Glacier National Park.

A large population of grizzly bears lives inland in Alaska and Canada.

Communication: Grizzly bears use sounds, movement and smells to communicate. They growl, moan or grunt, especially when females are communicating with their young. Grizzly bears also rub their bodies on trees and the ground to mark their territory and find mates.

Life History and Reproduction: Winter can be very tough for wildlife, because the season brings harsh weather and little food. Grizzly bears try to outlast the winter by going into hibernation.

Throughout the summer and autumn, grizzlies build up fat reserves by consuming large quantities of food. In late fall or winter, grizzly bears find a hillside and dig a hole to serve as a protective shelter. When inside the den, grizzly bears slow down their heart rate, temperature and metabolic activity and live off of stored fat reserves.

Depending on the weather and their fat reserves, grizzly bears can stay in the den for over 7 months. They don’t even go to the bathroom during this time! Grizzly bear hibernation is not a true hibernation, because they can readily wake from their winter sleep.

Grizzly bears begin to look for mates in late spring and early summer. Females mate with several males throughout the breeding season. When a female grizzly becomes pregnant, the development of the embryo temporarily stops for several months. The female spends the summer eating excessive amounts of food and storing up as much fat as possible. The fat is necessary for her and her cubs to survive the winter.

When female grizzlies enter hibernation, the embryo restarts its development. In January or February, female grizzly bears give birth to 1-4 cubs (usually 2). The female will care for her young inside the den until spring when they finally step out into the world.

The mother cares for her young for at least 2-3 more years. She feeds and protects them. Eventually, the mother will leave her cubs and they'll begin their life alone. At around 5 years of age, grizzly bears reach sexual maturity.

Grizzly bears are mainly solitary and territorial, except for mothers and her cubs or when a plentiful food source is discovered. Grizzlies are known to congregate at rivers with many fish.

Grizzlies can run pretty fast, reaching speeds upwards of 40 miles per hour. They are good swimmers too. Young grizzly bears can climb trees to evade danger, but they lose this ability with age.

Threats to Grizzly Bears: