Ursus arctos horribilis

Female gizzly in Yellowstone National Park, USA (Xinem, flickr.com/photos/christinestephens/4765579640/in/photostream/)

Accepted scientific name:  Ursus arctos horribilis (Ord, 1815)

Description:  A large bear, most commonly dark brown in colour but can range from blonde through to black.  The often grizzled appearance, which gives these bears their common name, is caused by the light coloured tips of the long guard hairs over the shoulders and back.  The bears have a distinctive hump on the shoulders and a slightly dished profile to the face.  The front claws are noticeably long.  There is considerable variation in the size of Ursus arctos horribilis from population to population, depending upon the food available.  Adult males typically weigh 135 to 390 kg, females 95 to 205 kg.  Adults are usually between 90 and 110 cm at the shoulder.  Grizzly bears from the interior are around two-thirds the size of the coastal and island bears of Alaska.

Range:  Localised populations in western Canada and in the states of Alaska, Idaho, Montana, Washington and Wyoming in the USA.

Present and historic range of Ursus arctos horribilis  NOTE: Five morphological forms of  U. a. horribilis are sometimes recognised as separate subspecies (and are listed on this site), however many authorities recognise only two subspecies of brown bear in North America, U.a. horribilis and the Kodiak bear (U.a. middendorffi). This map reflects that position. (See also “More Information” below.)  (By Cephas – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5935614)

Habitat:  Grizzly bears occupy a wide range of habitats including coastal, boreal and deciduous forests, sub-alpine mountain regions and tundra.  They were once abundant on the central plains of North America but were hunted into extinction in these areas.

Status:  Brown bears are listed as “of least concern” by the IUCN and listed in CITES Appendix II.  There are around 1,000 grizzly bears in the lower 48 states of the USA, around 30,000 in Alaska and around 16,000 in Canada (these figures include all North American populations of Ursus arctos, except for U.a.middendorffi; see “More Information” below).  On July 28, 1975  the grizzly was listed in the US Federal Register as endangered.  On August 1st, 2017 the bears were delisted by the U.S. Fish & Wildlife Service, and management was turned over to the states.  It seems likely that some or all of these states will issue hunting permits for grizzlies.

Life span:  Up to 25 years in the wild, up to 47 years in captivity.    The oldest recorded bears in Alaska were a 38 year old male and a 39 year old female.

Food:  Grizzly bears are omnivorous and eat a wide range of roots, tubers, grasses, sedges, flowers, fruits, berries and nuts.  They also eat salmon, other fish, insects, small mammals and carrion when found.  They will take ungulates (particularly newborns) such as elk, deer and moose.

Behaviour:  The bears reach sexual maturity between the ages of four and seven years.  Mating occurs between late April and July.  The bears go into winter dens usually in October or November and emerge in April,  May or June.  Cubs are born in the den between January and March, litters usually being of two or three cubs but can be of one or four.  They will remain with the mother for two to three years during which time she will not become pregnant again.  Except for mating and for mothers with cubs, grizzly bears are solitary although they will congregate in groups where there are plentiful sources of food, such as at salmon spawning grounds.

Threats:  Habitat loss, habitat fragmentation, conflicts with humans and poaching including for body parts to be used in medicine.  Hunting is generally well regulated and based upon reliable population estimates but may not be sustainable at present levels in Canada.  It seems likely that the bears are or will soon be affected by climate change either directly or indirectly as habitat and food sources change or disappear.


Many authorities recognise only two subspecies of brown bear in North America; this subspecies, the grizzly bear (U.a. horribilis), and the Kodiak bear (U.a. middendorffi).  In 1918 Clinton Hart Merriam divided the North American brown bears into 86 subspecies based upon small physical differences, mainly relating to skull measurements.  Today some experts believe that there is stillI sufficient evidence to warrant classifying five further subspecies on the continent in addition to the grizzly and Kodiak bears.  These each have a separate entry on this website and are the Alaskan (U.a. alascensis), Dall (U.a. dalli), Peninsular (U.a. gyas), Sitka (U.a. sitkensis) and Stickeen (U.a. stikeenensis) brown bears.  Much of the information recorded for these bears is similar to or identical to the above information for the grizzly bear.

 Grizzly bears deserve immediate legal protection in Canada (March 13, 2013)

More links will be added here soon.

Page created 10 August 2017








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