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Brown Bear
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Carnivora
Family:
Ursidae
Genus:
Ursus
Species:
Ursus arctos
Binomial name
Ursus arctos
Ursus arctos range map.


The brown bear (Ursus arctos) is an omnivorous mammal of the order carnivora, distributed across much of northern Eurasia and North America. It weighs between 130–700 kg (290-1,500 pounds) and its larger populations match the Polar bear as the largest extant land carnivores. While the brown bear's range has shrunk, and it has faced local extinctions, it remains listed as a least concern species with a total population of approximately 200,000. Its principal range countries are Russia, the United States (especially Alaska), and Canada.

The species primarily feeds on vegetable matter, including roots and fungi. Fish are a primary source of meat, and it will also kill small mammals on land. Larger mammals, such as deer, are taken more occasionally. Adult brown bears face no serious competition from other predators and can match wolf packs and large felines, often driving them off their kills.

It is sometimes referred to as the bruin, from Middle English, based on the name of the bear in History of Reynard the Fox, translated by William Caxton, from Middle Dutch bruun or bruyn.

Description

A Eurasian Brown Bear running. Brown bears can be fast runners despite their size, capable of speeds of up to 56 km/h (35 mph)

Brown bears have furry coats in shades of blonde, brown, black, or a combination of those colors. The longer outer guard hairs of the brown bear are often tipped with white or silver, giving a "grizzled" appearance. Their tail is 4-4.8 inches long.[2] Like all bears, brown bears are plantigrades and can stand up on their hind legs for extended periods of time. Brown bears have a large hump of muscle over their shoulders which distinguishes them from other species.[3] Brown bears are very powerful, even if considered pound for pound; a large specimen can break a neck or spine of a fully grown buffalo with a single blow.[citation needed] The forearms end in massive paws with claws up to 15 cm (5.9 inches) in length which are mainly used for digging. Brown bear claws are not retractable, and have relatively blunt points. Their heads are large and round with a concave facial profile, a characteristic used to distinguish them from other bears. Males are 38-50% larger than females.[2] The normal range of physical dimensions for a brown bear is a head-and-body length of 1.7 to 2.8 m (5.6 to 9.2 feet) and a shoulder height 90 to 150 cm (35 to 59 inches). The smallest subspecies is the Syrian Brown Bear, with mature females weighing as little as 150 kg (331 lb). The largest subspecies of the brown bear are the Kodiak bear and the bears from coastal Russia and Alaska. It is not unusual for large male Kodiak Bears to stand over 3 m (10 feet) while on their hind legs and to weigh about 680 kg (1,500 lb). The largest wild Kodiak bear on record weighed over 1,100 kilograms (2,500 pounds).[2]. Bears raised in zoos are often heavier than wild bears because of regular feeding and limited movement. In zoos, bears may weigh up to 900 kilograms (2,000 pounds), one example being "Goliath" from New Jersey's Space Farms Zoo and Museum. Size seems related to food availability, with subspecies distinctions being more related to nutrition rather than geographical location. [4] In spite of their size, some brown bears have been clocked at speeds in excess of 56 km/h (35 mph).

Distribution and habitat

Brown Bear at Brooks Falls

There are about 200,000 brown bears in the world. The largest populations are in Russia, with 120,000, the United States with 32,500, and Canada with 21,750. 95% of the brown bear population in the United States is in Alaska, though in the West they are repopulating slowly but steadily along the Rockies and plains. Although many hold on to the belief that some brown bears may be present in Mexico and the Atlas Mountains of Morocco, both are almost certainly extinct. The last Mexican brown bear was shot in 1960. In Europe, there are 14,000 brown bears in ten separate fragmented populations, from Spain in the west, to Russia in the east, and from Scandinavia in the north to Romania and Bulgaria in the south. They are extinct in the British Isles, extremely threatened in France and Spain, and in trouble over most of Central Europe. The brown bear is Finland's national animal. The Carpathian brown bear population is the largest in Europe outside Russia, estimated at 4,500 to 5,000 bears.

Brown bears were once native to Asia, the Atlas Mountains in Africa, Europe and North America,[5] but are now extinct in some areas and their populations have greatly decreased in other areas. They prefer semi-open country, usually in mountainous areas.

Brown bears live in Alaska, east through the Yukon and Northwest Territories, south through British Columbia and through the western half of Alberta. Isolated populations exist in northwestern Washington, northern Idaho, western Montana, and northwestern Wyoming.

The population of brown bears in the Pyrenees mountain range between France and Spain is so low, estimated at fourteen to eighteen with a shortage of females, that bears, mostly female, from Slovenia were released in the spring of 2006 to alleviate the imbalance and preserve the species' presence in the area, despite protests from French farmers.

In Arctic areas, the potential habitat of the brown bear is increasing. The warming of that region has allowed the species to move farther and farther north into what was once exclusively the domain of the polar bear. In non-Arctic areas, habitat loss is blamed as the leading cause of endangerment, followed by hunting.

North American brown bears seem to prefer open landscapes, whereas in Eurasia they inhabit mostly dense forests. It is thought that the Eurasian bears which colonized America were tundra adapted, something indicated by brown bears in the Chukotka Peninsula on the Asian side of Bering Strait, which are the only Asian brown bears to live year-round in lowland tundra like their American cousins.[6]

Brown bear in prehistory

North America

The brown bear has existed in North America since at least the most recent ice age, though it is thought that the larger, taller, and stronger giant short-faced bear or bulldog bear was the dominant carnivore at the time. The giant short-faced bear was a tall, thin animal adapted to eat large mammals, whereas the grizzly or brown bear has teeth appropriate for its omnivorous diet. The giant short-faced bear, on average, weighed twice as much as the grizzly, despite some exceptional grizzly bears in the later Old West that weighed 800 kilograms.

The brown bear also shared North America with the American lion and Smilodon, carnivorous competitors. The modern grizzly can eat plants, insects, carrion, and small and large animals. The American lion, Smilodon, and giant short-faced bear had a more limited range of food, making them vulnerable to starvation as the supply of available large mammals decreased, possibly due to hunting by humans.

The time of the Arctodus extinction is about the same as that of the long-horned Bison and other megafauna. Both of these animals were replaced by Eurasian immigrants, specifically the Brown Bear and American Bison. Since this was also about the same time as the Clovis tool kit hunting culture appeared in North America, with culturally advanced humans entering the Americas from Asia, the implication is that the brown bear was better adapted to human competition than the megafauna, presumably due to a long term coexistence in the Old World with people.

The extinction of ice-age herbivorous megafauna resulted in the extinction of the sabertooth, American lion, and giant short-faced bear, leaving the brown bear as the major large predator in North America, with the gray wolf, the jaguar in the south, the American black bear, and cougar also competing for large prey. The origin of human presence in America is widely accepted to have occurred across the Bering Land Bridge with the largest known immigration being that of the Paleo Indians at about the last ice age, bringing with them the Clovis point and advanced hunting techniques (see: Migration to the New World). When the last ice age ended about 10,000 years ago, brown bears from farther south in North America slowly expanded their range northward and back up into Alaska. Today there are three genetically distinct grizzly bear clades in North America: the Alaskan-Yukon Grizzly, the Alberta-Saskatchewan lineage, and those found in the Washington-Idaho-Montana-Wyoming area.

Eurasia

In Europe, the brown bear shared its habitat with other predators such as the Cave lion, Cave hyena and the larger, closely related Cave bear, which the brown bear ultimately outlasted. The cave bear was hunted by Neanderthals who may have had a religion relating to this bear, the Cave Bear Cult, but the Neanderthal population was too small for their consumption of cave bear to result in the species' extinction, and the cave bear outlasted the Neanderthals by 18,000 years, becoming extinct about 10,000 years ago. The cave bear and brown bear diets were similar, and the two species probably lived in the same area at the same time. Why the cave bear died out is not known.

Behavior

The brown bear is primarily nocturnal and, in the summer, puts on up to 180 kg (400 pounds) of fat, on which it relies to make it through winter, when it becomes very lethargic. Although they are not full hibernators, and can be woken easily, both sexes like to den in a protected spot such as a cave, crevice, or hollow log during the winter months. Brown bear are mostly solitary, although they may gather in large numbers at major food sources and form social hierarchies based on age and size.[7]

Reproduction

File:Bear and cubs fapas.jpg
Female Cantabrian brown bear and cubs. With kind permission of Fapas (Conservation NGO - Foundation for the Protection of Wild Animals)

The mating season takes place from late May through early July. Being serially monogamous, brown bears will remain with the same mate from several days to a couple of weeks. Females become sexually mature between the age of 5 and 7 years, while males will usually not mate until a few years later when they are large and strong enough to successfully compete with other males for mating rights. Through the process of delayed implantation, a female's fertilized egg will divide and float free within the uterus for six months. During winter dormancy, the fetus will attach itself to the uterine wall and the cubs will be born after an eight-week period while the mother sleeps. Should the mother not gain enough weight to survive through the winter, the embryo will not implant and be reabsorbed into the body. The average litter number is between one and four, with two being the most common number, though there have been cases of bears with five cubs, though it is not unusual for females to adopt strange cubs. The size of a litter depends on a number of factors such as the age of the mother, geographic location and food supply. Older females tend to give birth to larger litters. The cubs are blind, toothless, hairless and weigh less than 1 pound at birth. They feed on their mother’s milk until spring and as late as early summer depending on climate conditions. The cubs, which will weigh from 15 to 20 pounds at this time, will have developed enough to follow her and begin to forage for solid food. Cubs will remain with their mother from two to four years, during which time they will learn survival techniques such as which foods have the highest nutritional values and where to attain them, how to hunt, how to fish, how to defend themselves and where to den. The cubs learn by following and imitating their mother’s actions during the period they are with her.[8] Brown bears practice infanticide.[9] An adult male bear will kill the cubs of another bear to make the female sexually receptive. Cubs will flee up a tree when they sight a strange male bear.

Dietary habits

Brown bear feeding on salmon

They are omnivores and feed on a variety of plant products, including berries, roots, and sprouts, fungi as well as meat products such as fish, insects, and small mammals. Despite their reputation, most brown bears are not particularly carnivorous as they derive up to 90% of their dietary food energy from vegetable matter.[1] Their jaw structure has evolved to fit their dietary habits and lacks strong, sharp canine teeth of true predators. Their diet varies enormously throughout their differing ranges. For example, bears in Yellowstone eat an enormous number of moths during the summer, sometimes as many as 40,000 in a day,[2] and may derive up to a third of their food energy from these insects.[3] Locally, in areas of Russia and Alaska, brown bears feed mostly on spawning salmon, and the nutrition and abundance of this food accounts for the enormous size of the bears from these areas. Brown bears also occasionally prey on deer (Odocoeilus spp.; Dama spp., Capreolus spp.), Red Deer (Cervus elaphus or American elk), moose (Alces alces) and Bison (Bison bison spp., Bison bonasus). When brown bears attack these animals, they tend to choose the young ones since they are much easier to catch. When hunting, the brown bear uses its sharp canine teeth for neck-biting its prey. They also feed on carrion and will use their size to intimidate other predators such as wolves, cougars, smaller bears and tigers from their kills.

Interspecific predatory relationships

Brown bears will often use their large size to intimidate wolves from their kills. In Yellowstone National Park, brown bears pirate wolf kills so often that Yellowstone’s Wolf Project Director Doug Smith once wrote: "It’s not a matter of if the bears will come calling after a kill, but when." Though conflict over carcasses is common, the two predators will on some rare occasions tolerate each other on the same kill. Both species will prey on each others cubs, given the opportunity. [10]

Reconstruction of a brown bear confronting a wolf pack by Adolph Murie (1944)

Adults bears are generally immune from predatory attacks from anything other than another bear, however, in the Russian Far East brown bears, along with smaller Asiatic black bears constitute 5-8% of the diet of Siberian tigers.[11] In particular, the brown bears input is estimated as 1-1,5%.[12]Tigers generally avoid full-grown male brown bears (which weigh more than 200 kg in this region), but will quite readily predate on smaller females and young individuals. Even bears of the same size are a force to be reckoned with when confronted head on. Scientists report about 12 combat incidents when tigers were killed and eaten by brown bears (including female tigers and young male adults).[12] Some bears emerging from hibernation will seek out tigers in order to steal their kills. Tigers will usually stand their ground and defend their kills, unless the bear is a large male.[13]

Brown bears usually dominate other bear species in areas where they coexist. Due to their smaller size, American black bears are at a competitive disadvantage over brown bears in open, non-forested areas. Although displacement of black bears by brown bears has been documented, actual interspecific killing of black bears by brown bears has only occasionally been reported. The diurnal black bear's habit of living in heavily forested areas as opposed to the largely nocturnal brown bear's preference for open spaces usually ensures that the two species avoid confrontations in areas where they are sympatric.[14] There has been a recent increase in interactions between brown bears and polar bears, theorized to be caused by global warming. Brown bears have been seen moving increasingly northward into territories formerly claimed by polar bears. Brown bears tend to dominate polar bears in disputes over carcasses[15] and dead polar bear cubs have been found in brown bear dens.[16] Giant Panda cubs have also been reportedly eaten by brown bears.[2]

Habituation to human areas

Front paw imprint.

Bears become attracted to human created food sources such as garbage dumps, litter bins, and dumpsters; and venture into human dwellings or barns in search of food as humans encroach into bear habitat. In the U.S., bears sometimes kill and eat farm animals. When bears come to associate human activity with a "food reward", a bear is likely to continue to become emboldened and the likeliness of human-bear encounters increases, as they may return to the same location despite relocation. The saying, "a fed bear is a dead bear," has come into use to popularize the idea that allowing bears to scavenge human garbage, such as trash cans and campers' backpacks, pet food, or other food sources that draw the bear into contact with humans can result in a bear's death.

Relocation has been used to separate the bear from the human environment, but it does not address the problem bear's newly learned humans-as-food-source behavior. Nor does it address the environmental situations which created the human habituated bear. "Placing a bear in habitat used by other bears may lead to competition and social conflict, and result in the injury or death of the less dominant bear."[17]

Yellowstone National Park, an enormous reserve located in the Western United States, contains prime habitat for the Grizzly Bear (Ursus arctos horribilis), but due to the enormous number of visitors, human-bear encounters are common. The scenic beauty of the area has led to an influx of people moving into the area. In addition, because there are so many bear relocations to the same remote areas of Yellowstone, and because male bears tend to dominate the center of the relocation zone, female bears tend to be pushed to the boundaries of the region and beyond. The result is that a large proportion of repeat offenders, bears that are killed for public safety, are females. This creates a further depressive effect on an already endangered species. The grizzly bear is officially described as threatened in the U.S. Though the problem is most significant with regard to grizzlies, these issues affect the other types of brown bear as well.

In Europe, part of the problem lies with shepherds; over the past two centuries, many sheep and goat herders have gradually abandoned the more traditional practice of using dogs to guard flocks, which have concurrently grown larger. Typically they allow the herds to graze freely over sizeable tracts of land. As bears reclaim parts of their range, they may eat livestock. The shepherd is forced to shoot the bear to protect his livelihood.

Subspecies

Syrian Brown Bear in Jerusalem Biblical Zoo

There is little agreement on classification of brown bears. Some systems have proposed as many as 90 sub-species while recent DNA analysis has identified as few as five clades.[18] DNA analysis has recently revealed that the identified subspecies of brown bears, both Eurasian and North American, are genetically quite homogeneous, and that their genetic phylogeography does not correspond to their traditional taxonomy.[19] The subspecies of brown bears have been listed as follows: one of which (called clade I by Waits, et al., part of the subspecies identified as U. a. sitkensis, by Hall and U. a. dalli by Kurtén) appears to be more closely related to the polar bear than to other brown bears.[19]

  • Ursus arctos arctos – Eurasian Brown Bear
  • Ursus arctos ognevi – East from Kolyma River
  • Ursus arctos beringianus – Kamchatka Brown Bear; Kamchatka Peninsula and Paramushir Island
  • Ursus arctos crowtheri – Atlas Bear (extinct)
  • Ursus arctos gobiensis – Gobi bear; Mongolia
  • Ursus arctos horribilis – Grizzly Bear; Canada and United States
  • Ursus arctos isabellinus – Himalayan Brown Bear; Nepal, Pakistan and Northern India
  • Ursus arctos formicarius – Carpathian Bear;
  • Ursus arctos lasiotus – Amur brown bear ( or "Ussuri brown bear", "black grizzly" or "horse bear"), Russia: Southern Kuril Islands, Sakhalin, Maritime Territory, and the Ussuri/Amur river region south of the Stanovoy Range. China: Northeastern Heilongjiang. Japan: Hokkaido
  • Ursus arctos marsicanus – Marsican Brown Bear; Central Italy (critically endangered)
  • Ursus arctos meridionalis – Northern Caucasus
  • Ursus arctos middendorffi – Kodiak Bear (or "Alaska Coastal Brown Bear"); Kodiak, Afognak, Shuyak, Admiralty, Chicagof, Baranof Islands (Alaska), plus other islands in southeastern Alaska and along the mainland coast of southeastern Alaska
  • Ursus arctos nelsoni – Mexican Grizzly Bear; (extinct?)
  • Ursus arctos collaris – Siberian Brown Bear; Siberia (except for the habitat of the Kamchatka and Amur brown bears.) Also in northern Mongolia, far northern Xinjiang, and extreme eastern Kazakhstan.
  • Ursus arctos pruinosus – Tibetan Blue Bear; Western China
  • Ursus arctos syriacus – Syrian Brown Bear; Middle East
  • Ursus arctos yesoensis – Hokkaido Brown Bear; Japan
  • Ursus arctos piscator – Bergman's Bear (extinct?)

Hybrids

Polar/Brown Bear Hybrid, Rothschild Museum, Tring

A grizzly–polar bear hybrid is a rare ursid hybrid resulting from a union of a brown bear and a polar bear. It has occurred both in captivity and in the wild. In 2006, the occurrence of this hybrid in nature was confirmed by testing the DNA of a strange-looking bear that had been shot in the Canadian arctic.[20] Previously, the hybrid had been produced in zoos and was considered a "cryptid" (a hypothesized animal for which there is no scientific proof of existence in the wild).

Bear encounters

There are an average of two fatal attacks a year in North America.[21] In Scandinavia, there are only four known cases during the last 100 years in which humans were killed by bears. Attacks usually occur because the bear is injured or a human encounters a mother bear with cubs. Some types of bears, such as polar bears, are more likely to attack humans when searching for food, while American black bears are much less likely to attack.

The Scandinavian Bear Research project lists the following situations as potentially dangerous:

  1. Meeting an injured bear
  2. A human suddenly appearing
  3. Meeting a bear in its cave
  4. Meeting a bear who has been provoked

See also

Wikimedia Commons has media related to Ursus arctos.
Wikispecies has information related to Ursus arctos.

References

  1. ^ Template:IUCN2006
  2. ^ a b c d Brown, Gary (1996). Great Bear Almanac. pp. pp.340. ISBN 1558214747. {{cite book}}: |pages= has extra text (help)
  3. ^ Learn to Identify Black Bears and Grizzly (Brown) Bears
  4. ^ Macdonald, David (1984). The Encyclopedia of Mammals: 1. pp. pp.446. ISBN 0-04-500028-x. {{cite book}}: |pages= has extra text (help)
  5. ^ "http://news.bbc.co.uk/2/hi/science/nature/4003325.stm". {{cite web}}: External link in |title= (help)
  6. ^ Brown Bear Hunting in Russia
  7. ^ Animal Diversity Web - Ursus arctos
  8. ^ Brown Bear Reproduction
  9. ^ Mating Strategies in Relation to Sexually Selected Infanticide in a Non-Social Carnivore: the Brown Bear
  10. ^ http://www.wolf.org/wolves/news/iwmag/2006/spring/personalencounter.pdf
  11. ^ Vratislav Mazak: Der Tiger. Nachdruck der 3. Auflage von 1983. Westarp Wissenschaften Hohenwarsleben, 2004 ISBN 3 894327596http
  12. ^ a b Seryodkin, Ivan (2006). "The ecology, behavior, management and conservation status of brown bears in Sikhote-Alin (in Russian)". Far Eastern National University, Vladivostok, Russia. pp. pp.1-252. {{cite web}}: |pages= has extra text (help)
  13. ^ Matthiessen, Peter (2001). Tigers In The Snow. North Point Press. ISBN 0865475962. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  14. ^ http://www.nrmsc.usgs.gov/products/Predation_Papers.pdf
  15. ^ adn.com | front : Polar bears, grizzlies increasingly gather on North Slope
  16. ^ ABC News: Grizzlies Encroaching on Polar Bear Country
  17. ^ "http://www.bearsmart.com/managingBears/Relocation.html". {{cite web}}: External link in |title= (help)
  18. ^ U.S. Fish and Wildlife Service (November 17, 2006). "Endangered and Threatened Wildlife and Plants; Designating the Greater Yellowstone Ecosystem Population of Grizzly Bears as a Distinct Population Segment; Removing the Yellowstone Distinct Population Segment of Grizzly Bears From the Federal List of Endangered and Threatened Wildlife" (PDF). Federal Register / Vol. 70, No. 221. pp. 69854–69884. {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  19. ^ a b Lisette P. Waits, Sandra L. Talbot, R.H. Ward and G. F. Shields (1998). "Mitochondrial DNA Phylogeography of the North American Brown Bear and Implications for Conservation". Conservation Biology. pp. 408–417. {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  20. ^ "Wild find: Half grizzly, half polar bear: Hunter bags what expert 'never thought would happen' in wild". MSNBC.MSN.com. May 11, 2006. Retrieved 2006-05-14. {{cite news}}: Check date values in: |date= (help)
  21. ^ Bear Attacks: Their Causes and Avoidance, Stephen Herrero, revised edition, 2002.


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