Grizzly Bear
The Grizzly Bear, sometimes called the Silvertip Bear, is a powerful brownish-yellow
bear that lives in the uplands of western
North America. It has traditionally been treated as a subspecies,
Ursus arctos horribilis, of the
brown bear living in North America.
Grizzly Bears reach weights of 180680 kg ; the male is on average 1.8 times as heavy as the female, an example of
sexual dimorphism. Their coloring ranges widely across geographic areas, from blond to deep brown or black. These differences, once attributed to subspeciation, are now thought to be primarily due to the different environments these bears inhabit, particularly with regard to diet and temperature.
Encyclopedia
The
Grizzly Bear, sometimes called the
Silvertip Bear, is a powerful brownish-yellow
bear that lives in the uplands of western
North America. It has traditionally been treated as a subspecies,
Ursus arctos horribilis, of the
brown bear living in North America.
Grizzly Bears reach weights of 180–680 kg ; the male is on average 1.8 times as heavy as the female, an example of
sexual dimorphism. Their coloring ranges widely across geographic areas, from blond to deep brown or black. These differences, once attributed to subspeciation, are now thought to be primarily due to the different environments these bears inhabit, particularly with regard to diet and temperature.
The Grizzly has a large hump over the shoulders which is a muscle mass used to power the forelimbs in digging. The head is large and round with a concave facial profile. In spite of their massive size, these bears can run at speeds of up to 55 km/h .
Normally a solitary,
nocturnally active animal, in coastal areas the Grizzly congregates alongside streams and rivers during the salmon spawn. Every other year females produce one to four young which are small and weigh only about 500 g . Sows are very protective of their offspring.
The current range of the Grizzly Bear extends from
Alaska, south through much of Western
Canada, and into the northern
Northwestern United States including
Idaho,
Montana and
Wyoming. Its original range also included much of western and southern United States, but it has been
extirpated in those areas. It is expected that the grizzly's repopulation of its U.S. range will be a slow process due equally to the ramifications of reintroducing such a large animal to areas which are prized for agriculture and livestock and also because of the bear's slow reproductive habits .
Diet
Being
omnivores, grizzlies feed on a variety of plants and berries including roots or sprouts and
fungi, as well as insects and smaller mammals; what is eaten depends largely on time of year and precise location. The larger bears have been known to prey on large mammals such as
moose,
sheep, and
caribou. Grizzly bears in general will feed on fish like
salmon,
trout, and bass, but those with access to a more protein-enriched diet in coastal areas can grow much larger than their
herbivorous cousins.
In preparation for winter, bears will gain hundreds of kilograms of
fat before going into a state of false hibernation. There is some debate amongst professionals as to whether or not Grizzly Bears technically hibernate. Much of this debate revolves around
body temperature and the ability for the bears to move around during hibernation on occasion. One interesting adaptation is that Grizzly Bears have the ability to
partially recycle their body wastes during this period. In some areas where food is plentiful all year round, Grizzly Bears will forego hibernation altogether.
Legal status
The Grizzly Bear is
listed as threatened in the contiguous United States, and
endangered in parts of
Canada. It is currently rapidly repopulating areas where it was previously
extirpated. On January 9, 2006, the US Fish and Wildlife service to remove Yellowstone grizzlies from the
list of threatened and protected species.
Some biologists have argued that the word
horribilis should be removed from the bear's taxonomic name, as its negative connotations may hinder conservation efforts. This change would not be permitted by the International Code of Zoological Nomenclature.
Trivia
See also
- List of fatal bear attacks in North America by decade
References
- 2.1 MB PDF file.
- Cronin, M.A., Amstrup, S.C., Garner, G.W., and Vyse, E.R., 1991. Interspecific and specific mitochondrial DNA variation in North American bears . Canadian Journal of Zoology 69: 2985-2992.
- Waits, L.P., Talbot, S.L., Ward, R.H., and Shields, G.F., 1998. Mitochondrial DNA phylogeography of the North American brown bear and implications for conservation. Conservation Biology 12: 408-417.
- , which inspired the victim to create a better bear-repellent pepper spray. Commercial site with very graphic photographs of injury from bear attack.
