Learning about
Grizzly bear
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| Ursus arctos horribilis (Ord, 1815) |
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 kilograms (400–1,500 pounds); the male is on average 1.8 times as heavy as the female, an example of sexual dimorphism. This dimorphism suggests that size is an important factor in male/male competition. 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 fifty-five kilometers per hour (thirty-five miles per hour).
Normally a solitary nocturnally active animal, in coastal areas the grizzly congregates alongside streams and rivers during the salmon spawn. Every other year females (sows) produce one to four young (most commonly two) which are small and weigh only about 500 grams (one pound). 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 portions of the Northwestern United States including Idaho, Montana and Wyoming, extending as far south as Yellowstone and Grand Teton National Parks. Its original range also included much of the Great Plains and the Southwestern states, but it has been extirpated in most of those areas. The grizzly currently enjoys legal protection in the United States. However, it is expected that its repopulation of its former 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 to the bear's slow reproductive habits (bears invest a good deal of time in raising young). There are currently about 60,000 wild grizzly bears currently located throughout North America.
Brown bears (of which the grizzly bear is a subspecies) can live up to thirty years in the wild, though twenty to twenty-five is normal.[1]
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Diet
Bears have been known to prey on large mammals such as moose, deer, sheep, and caribou. Grizzly bears will feed on fish such as salmon, trout, and bass, and those with access to a more protein-enriched diet in coastal areas potentially grow larger than interior individuals. Grizzly bears will readily scavenge food, behavior that can lead them into conflict with other species, such as wolves and humans.
The Grizzly bears which reside in the American northwest are not as large as Canadian or Alaskan sub-species Ursus arctos. This is due, in part, to the richness of their diet which in Yellowstone consists of whitebark pine nuts, roots, tubers, grasses, various rodents, army cutworm moths and scavenged carcasses, none of which match the fat content of the salmon available in Alaska. During early spring, as the bears emerge from their dens, elk and bison calves are actively sought. The bear will move in a zig-zag pattern, nose to the ground, hoping to find a meal.
In preparation for winter, bears will gain hundreds of kilograms of fat, during a period of hyperphagia, before going into a state of false hibernation. The bear will often wait for a substantial snowstorm before it enters its den. Presumably, this behavior lessens the chances that predators will be able to locate the den. The dens themselves are typically located at elevations above 6,000 feet on northern-facing slopes. There is some debate amongst professionals as to whether grizzly bears technically hibernate. Much of the debate revolves around body temperature and the ability of the bears to move around during hibernation on occasion. Grizzly bears have the ability to "partially" recycle their body wastes during this period. In some areas where food is plentiful year round, grizzly bears forgo hibernation altogether.
Interspecies competition
Most notable in Yellowstone have been the interactions between gray wolves and grizzly bears. Since the reintroduction of gray wolves to Yellowstone, many lucky visitors have witnessed a once common struggle between a keystone species, the grizzly bear, and its historic rival, the gray wolf. The interactions of U. arctos horribilis with the wolves of Yellowstone have been under considerable study. Typically, the conflict will be over a carcass, which is commonly an elk killed by wolves. The grizzly bear will use its strong sense of smell to locate the kill first. Then the wolves and grizzly will play a game of cat and mouse. One wolf may try to distract the bear while the others feed. The bear then may retaliate by chasing the wolves. If the wolves become aggressive with the bear it is normally in the form of careful nips at its hind legs. Thus, the bear will sit down and ease its ability to protect itself in a full circle. Rarely do interactions such as these end in death or serious injury to either animal. One carcass simply isn't usually worth the risk to the wolves if the bear has the upper hand (due to strength and size) or the bear (if the wolves are too numerous or persistent). Over time, it seems the grizzly bears have benefited from the presence of the gray wolf because of increased food availability.
Safety camping in grizzly territory
During the continuous evolution of the grizzly bear a premium has been placed on spatial memory. Without this adaptation, the species would not be able to forage efficiently over large territories. This strong sense of memory thus ties in with their tendency to return to human habitations which rewarded them with food in the past. It is imperative for all campers in bear country (both black and grizzly) to maintain a "clean" site. Reports have indicated that something as innocuous as a tube of chap stick has enticed a bear to come near a campsite in search of food. Any bear conditioned to finding food around campsites will almost always return and expect the same reward. The bear is then a threat to campers and itself, since park rangers will be forced to euthanize it. For backcountry campers, hanging food between trees at a height unreachable to bears is a common procedure.
Safety hiking in grizzly territory
Hiking in grizzly territory requires a different set of rules than hiking in your local park. The consequences of making a mistake can be deadly and are well documented. First, it is imperative that you are aware of your surroundings at all times. Recognizing grizzly sign is the first defense in preventing an attack. A grizzly track is unlike that of a black bear in that one can trace a single line from the innermost (closest to the foot pad) point on the left toe to the innermost point on the right toe without intersecting the pad of the foot. Other signs include: talus slopes that appear raked, fallen logs which have been torn up, and high claw marks on trees. Surprising a bear typically precedes the most violent attacks. By making noise, at a cost to the ambient peacefulness of nature, you can assure yourself that a bear will know you are there. This technique works in the case of a lone grizzly wandering through the area, or the more dangerous high strung sow with cubs of the year. It will not work when a bear has a carcass near the trail. In this case, the hiker must listen for ravens or other scavengers which may too be hanging around the kill site. In any case, if the bear does not exit the premises as you approach, it's time to make a series of potentially life saving decisions. First, back away and talk to the bear in a calm voice. If it hasn't charged, it probably doesn't consider you a threat. Keep backing away (DO NOT RUN) and try in any way to make yourself seem less threatening. In the unfortunate event that the bear does charge, and you are not equipped with bear spray, promptly drop to the ground stomach first, leaving your backpack on as a barrier between the bear and you, and cover your head and ears with your arms (hands interlocking behind your head). Drawing your legs up tightly under you will also decrease the chances of a bite in a soft vulnerable arterial area, and of being dragged by that appendage. In this situation fighting back will almost certainly intensify and prolong the attack. Humans are ill equipped to fight grizzlies, so do not attempt such a feat.
Legal status
The grizzly bear is listed as threatened in the contiguous United States, and endangered in parts of Canada. In Alaska and parts of Canada however, the grizzly is still legally shot for sport by hunters. On January 9, 2006, the US Fish and Wildlife service proposed 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.
Protection
Many national parks, such as Yellowstone and Grand Teton, have laws and regulations in place to protect the bears. Also the grizzly bears are very protective of their young and are willing to go to any level to help them stay safe.
On March 22, 2007, The Federal Government stated that Grizzly bears in and around Yellowstone National Park no longer need Endangered Species Act protection.
Trivia
- The name “grizzly” comes from the hairs of its coat having silver-grey tips, see grizzly; the folk etymology derivation from the word grisly meaning “horrible”, though apt, is incorrect.
- In April 2006, the first grizzly-polar bear hybrid found in the wild was discovered at Banks Island, Canada, after being killed by a trophy hunter on a guided $50,000 hunt.
- The grizzly bear became the state animal of California in 1953 and appears on the state flag. The last grizzly bear in California was shot in August 1922 in Tulare County, eleven years after the state legislature had adopted the flag[2].
- It is a common misconception that grizzly bears cannot climb trees. They will climb trees if they have a food incentive.
