Grizzly Bear

California Trail

Location

In the Zoo

Scientific Information

Scientific Name: Ursus Arctos
Class: Mammalia
Order: Carnivora
Family: Ursidae
Genus: Ursus

Size

Male

Female

Height: 3-4.9 feet 3-4.9 feet
Length: 4.9-9.2 feet
Weight: 300-1200 pounds 175-550 pounds
Maturity: 5-10 years 5-10 years

Lifestyle and Lifespan

Diet: Omnivorous
Activity Timeframe: Diurnal
Interactivity: Solitary
Sexual Dimorphism: Yes
Gestation: 6.5-8.5 months
Lifespan in the Wild: 20-30 years
Lifespan in Captivity: 50 years

Geographic Range

NW North America, Scandinavis through Russia to Japan, scattered in S and E Europe, Middle East, Himalayas, China, & Mongolia

Conservation

Status in the Wild:
Threats:

Characteristics

Shoulder as high or higher than rump and colored dark brown to blonde. Fur grizzled or uniformly colored. Profile of muzzle will be concave, as opposed to the black bear that have straight or convex muzzles.

Species Specifics

Spanning 3 continents, it is the most widespread bear on earth. Possibly 3 different subspecies (N American grizzly, Kodiak, Eurasian brown) exist.

Physical Characteristics

Muscular shoulders and large claws allow them to dig up small mammals, insects, and roots better than black bears. They can swim well. Bears are the mammals able to survive for half a year or more without eating, drinking, urinating, or defecating. During hibernation, their body temperature lowers from ~100°F to ~93°F.

Ecology

Habitat

Forest, alpine, tundra, desert

Distribution

Home Range: Grizzlies are larger than black bears and have larger home ranges. A male's average range is 80-800 mi2, and a female's average range is 40-400 mi2.

Diet

Roots, tubers, forbs, grasses, sedges, fruits, pine seeds, insects, fish, rodents, ungulates.Seasonal Diet: Grizzly bear diets vary widely depending on their range and the season. Some are carnivorous, while others survive primarily on plants and eat meat only when opportunities arise. In North America, there are two main types of bear diets: inland and coastal. Inland bears eat roots in early spring and ungulates (like elk) that died or are weak from winter. As it warms, they will eat grasses, sedges, forbs, and tubers and will hunt the newly born of several species (elk, deer, moose, muskox, and caribou). Toward the fall they will eat fruits, seeds, and smaller mammals. Coastal bears eat tubers and sedges in early spring and summer, as well as Pacific razors and soft-shelled clams at low tide at exposed mudflats. Salmon are abundant from July to December, depending on the area. After the salmon run, coastal grizzlies will focus on berries, seeds, tubers and grasses.

Ecological Web

Ecological Role: This species serves many roles in ecosystem structure due to their omnivorous, opportunistic nature. Grizzlies are considered apex (top) predators and keep prey populations at a healthy level. In addition, they act as scavengers and remove diseases from the ecosystem and return nutrients to the soil. Predators: Their only predators are humans.

Activity and Behavior

Activity Pattern

Mainly crepuscular, but often active during the day, especially as the season gets closer to hibernation.

Behavior

There are theories that grizzlies maintain a higher body temperature during hibernation because they cannot hide as well as small creatures can and if they can wake up quickly, they can defend themselves from other predators if necessary. They sometimes cache food, to save for later and can congregate along salmon runs.

Social Behavior

Solitary, though ranges can overlap between the sexes. Males and females come together during estrus, and females care for their offspring for long periods. However, during the salmon run, it is not uncommon to see multiple bears, where they will form a social hierarchy (males are more dominant).

Reproductive Behavior

Mating occurs May-July, but the uterine implantation of blastocycts occurs in November, with birth 6-8 weeks after (during hibernation). The interval between successful litters is generally 2-5 years.

Offspring

Typically 2-3 cubs but can be 1-4. If females have only 1, they can abandon it (a female that stays with 1 cub for over 1 year ends would have fewer total young overall than if she abandoned the single cub and produced 3 the following year).

Conservation

Status

Least Concern by IUCN, CITES Appendix II (except Chinese & Mongolian populations under Appendix I), Endangered Species List in US outside of Alaska

Historical

Their range used to span across much of the northern hemisphere and there is not as much connectivity today. In California, a number of early hunters claimed to have each killed over 200 grizzlies within a single year. Within 100 years of the invention of the Sharps rifle, the California grizzly had been hunted to extinction. California's last grizzly was shot by rancher Jesse B. Agnew in August 1922, in Horse Corral Meadow, Tulare County.

Current Threats

Our Role

How You Can Help

Do not hunt bears and contact your government to express your interest in grizzly bear conservation and decreasing fragmentation between populations. Properly store your food and pick up trash when you go into bear territory. Drive safely and slowly to prevent road kills. Never come between a mother and her cubs. Depredation occurs with bears when they are too habituated to humans or if they attack. If we clean up after ourselves and pay attention to our surroundings, we can easily save the lives of bears. Express your interest in stopping the tradition of 'dancing bears' which persists in Turkey and Greece; circuses exploit their ability to stand on their hind legs.

Fascinating Facts

Early settlers in California often reported seeing 50 grizzlies in one day. In 1827, a California writer named Duhaunt Cilly claimed that grizzlies were so common around San Francisco that "they are often seen in herds."

By 1904, a grizzly pelt was worth $75, over a month's wages at that time. In 1915, the Animal Damage Control Program started in the US, leading animal control agents and bounty hunters to eradicate all predators, including grizzlies. By 1920, a grizzly hide was worth $120, but there were few grizzlies in the lower 48 left.

Grizzlies are so diverse and widespread that they were once divided into 232 living and 39 fossil species and subspecies (though they are all now considered a single species.

Though inland grizzly bears follow a seasonal diet mainly consisting of vegetation, Yellowstone grizzlies are an exception. Up to 95% of their energy intake is from meat because in the park fruit is rare while there are many ungulates.

References

Busch, Robert. The Grizzly Almanac. 2004

Convention on International Trade in Endangered Species of Wild Fauna and Flora Appendices I, II, and III. (2012). Retrieved April 12, 2012; from http://www.cites.org/eng/app/appendices.php

Elbroch, M & Rinehart, K. Peterson Reference Guides: Behavior of North American Mammals. 2011.

MacDonald, David. The Princeton Encyclopedia of Mammals. 2009.

Reif, Fiona. Peterson's Field Guides: Mammals of North America. 2006.

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9777 Golf Links Road Oakland, CA 94605