Ursus arctos

Brown Bears are solitary, powerful predators who can be aggressive to one another. There is a social hierarchy: adult males are dominant, and females with cubs are dominant over juvenile males and females without cubs. Brown Bears are omnivorous, consuming everything from mosses, fungi, herbs, grasses, fruits, berries, small vertebrates, insects, birds, and fish especially salmon during their spawning run to other mammals. They dig after burrowing mammals and take down large hoofed mammals caught in deep snow or otherwise disabled. They are excellent swimmers and have acute senses of hearing and smell, but poor eyesight, and can attack humans without warning. The largest North American males weigh more than 600 kg (1,325 pounds).

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The brown bear is the most widely distributed ursid. It once ranged across a large portion of North America, including northern Mexico (plus, at one time, much of the eastern half of the continent), throughout Europe, Asia, the Middle East, and even across North Africa. It presently occupies approximately 5,000,000 km² of the northwestern portion of North America, 800,000 km² of Europe (excluding Russia), and much of northern Asia. The largest numbers exist in Russia, U.S. (Alaska), and Canada. Many populations in Europe, and the more southerly portions of Asia and North America are small and isolated (Servheen et al. 1999, Swenson et al. 2000). A history of prolonged over-exploitation in Europe stretching back centuries resulted in the elimination of brown bears from many countries. The date of their extirpation from North Africa is uncertain, but they may have existed as late as the 1500s in the Sinai of Egypt (Manlius 1998) and mid-1800s in Algeria and Morocco (Hamdine et al. 1998). During the 20th Century, brown bears (called grizzly bears in interior North America) were extirpated in Mexico and a large portion of southwestern U.S. (Brown 1985, Mattson and Merrill 2002), while in Asia and the Middle East they have apparently been eliminated from Syria, and possibly Bhutan. Very small numbers of brown bears still remain in Iraq and Nepal (Gurung 2004, Ridings 2006). Andorra was reoccupied in 2003 from bears reintroduced into the French Pyrenees. A few wandering individuals recently crossed into Switzerland from Italy and into Lithuania from Latvia and Belarus, but not enough as yet to be considered extant populations.

The brown bear currently occurs in Afghanistan, Albania, Andorra (recently reoccupied), Armenia, Austria, Azerbaijan, Belarus, Bhutan (possibly extinct), Bosnia and Herzegovina, Bulgaria, Canada, China, Croatia, Czech Republic (possibly only vagrants), Estonia, Finland, France, Georgia, Greece, India, Iraq, Islamic Republic of Iran, Italy, Japan, Kazakhstan, Democratic People’s Republic of Korea, Kyrgyzstan, Latvia, the Former Yugoslav Republic of Macedonia, Mongolia, Montenegro, Nepal, Norway, Pakistan, Poland, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Sweden, Tajikistan, Turkey, Turkmenistan, Ukraine, United States, and Uzbekistan. The species has become Extinct during past 500 years in Algeria, Egypt, Germany, Hungary, Israel, Lebanon, Liechtenstein, Lithuania, Mexico, Moldova, Morocco, Palestinian Territory (Occupied), Portugal, San Marino, Switzerland, and Syrian Arab Republic. Extinctions due to human agency have taken place more than 500 years ago in Belgium, Denmark, Ireland, Jordan, Luxembourg, Monaco, Netherlands, Tunisia, United Kingdom, and the Vatican.

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Formerly throughout western North America, north from northern Mexico; northwestern Africa, all of the Palearctic from western Europe, Near and Middle East through the northern Himalayas to western and northern China and Chukot (Russia) and Hokkaido (Japan) (Wozencraft, in Wilson and Reeder 1993); see Pasitschniak-Arts (1993) for additional details. In North America, present range includes Alaska, northern and western Canada, northern Continental Divide in Montana, Cabinet/Yaak mountains in Montana/Idaho, Selkirk Mountains in Idaho/Washington, Northern Cascades in Washington, and Yellowstone area, Wyoming/Montana/Idaho. Some bears in the Cabinet-Yaak ecosystem of Montana and Idaho and Selkirk ecosystem of Idaho and Washington mingle in the Purcell Mountains in southern British Columbia, and movement data indicate that the Cabinet-Yaak and Selkirk populations are connected to a much larger population (several hundred bears) extending north into British Columbia (USFWS 1999). However, the listed distinct population segment is confined to the U.S. portion of these ecosystems. Common only in Alaska, parts of the Yukon, northern and coastal British Columbia, and portions of the northern Rocky Mountains. USFWS has proposed reintroduction in the Bitterroot ecosystem of east-central Idaho and adjacent Montana. In Europe, apart from northern Europe, distribution has shrunk to a few isolated populations in the Pyrenees, the Apenines, the Alps, the Balkan Peninsula, and the Carpathians (see Hartl and Hell 1994).

Ursus arctos once ranged throughout northern and central Europe, Asia, the Atlas mountains of Morocco and Algeria, and western North America as far south as Mexico. They are now found in extremely small numbers from western Europe and Palestine to eastern Siberia and the Himalayan region, possibly the Atlas Mountains of northwest Africa, and Hokkaido. Northern North American populations in Alaska and western Canada remain fairly stable. Many populations in the United States have been extirpated, including those of the Sierra Nevada and southern Rockies. Northern Mexican populations were extirpated in the 1960's.

Biogeographic Regions: nearctic (Native ); palearctic (Native )

Other Geographic Terms: holarctic

One of the largest of living carnivores, grizzly bears are 1 to 2.8 meters in length from head to rump and their tails are 65 to 210 mm long. They are 90 to 150 cm tall at the shoulder and can tower at an intimidating height of 8 feet when standing upright on their hind legs. They range in weight from 80 to more than 600 kg. On average, adult males are 8 to 10% larger than females. Ursus arctos is largest along the the coast of southern Alaska and on nearby islands where males average 389 kg and females average 207 kg, though some males have been weighed at as much as 780 kg. Distance between the canines is from 6 to 8 cm. Size rapidly declines to the north and east, with individuals in southwestern Yukon weighing only 140 kg on average. Fur is usually dark brown, but varies from cream to almost black. Individuals in the Rocky Mountains have long hairs along the shoulders and back which are frosted with white, giving a grizzled appearance, hence the common name grizzly bear in that region. Brown bears are extremely strong and have good endurance; they can kill a cow with one blow, outrun a horse, outswim an Olympian, and drag a dead elk uphill.

Range mass: 80 to 600 kg.

Range length: 1 to 2.8 m.

Other Physical Features: endothermic ; heterothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Brown bears occupy a variety of habitats, from desert edges to high mountain forests and ice fields. In North America they seem to prefer open areas such as tundra, alpine meadows, and coastlines. Historically, they were common on the Great Plains prior to the arrival of European settlers. In Siberia, Ursus arctos occurs primarily in forests, while European populations are restricted mainly to mountain woodlands. The main habitat requirement for Ursus arctos is some area with dense cover in which it can shelter by day.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: tundra ; taiga ; desert or dune ; savanna or grassland ; chaparral ; forest ; scrub forest ; mountains

Brown bears are omnivorous, eating almost anything nutritious. Their diet changes with seasonal availability of different food sources. They eat a wide variety of plant foods, including grasses, sedges, roots, moss, and bulbs. Fruits, nuts, berries, bulbs, and tubers are taken extensively during summer and early autumn. They consume insects, fungi, and roots at all times of the year and also dig mice, ground squirrels, marmots, and other fossorial animals out of their burrows. Moth larvae have been demonstrated to be especially important sources of protein and fat when brown bears are putting on fat in the fall. In the Canadian Rockies and other areas, grizzly bears (the subspecies of brown bear in that area) are quite carnivorous, hunting moose, elk, mountain sheep, and mountain goats. Occasionally black bears are preyed upon. In Alaska, brown bears have been observed to eat carrion and occasionally capture young calves of caribou and moose. Brown bears have also been observed to feed on vulnerable populations of breeding salmon in the summer in these areas.

Animal Foods: mammals; fish; carrion ; insects

Plant Foods: leaves; roots and tubers; seeds, grains, and nuts; fruit; bryophytes

Other Foods: fungus

Primary Diet: omnivore

Brown bears are important predators and seed dispersers in the ecosystems in which they live.

Because of their size and aggressiveness towards threats, brown bears are not often preyed upon. Humans have persecuted them throughout recent history and some cubs may be attacked by other bears or by mountain lions or wolves, although this is very rare.

Known Predators:

• humans (Homo sapiens)
• other brown bears (Ursus arctos)
• wolves (Canis lupus)
• mountain lions (Puma concolor)

Anti-predator Adaptations: cryptic

Brown bears communicate primarily through smells and sounds. Brown bears can be heard making moaning noises sometimes while they are foraging. They scratch and rub on trees and other landmarks to communicate territorial boundaries and reproductive status.

Brown bears have an excellent sense of smell (able to follow the scent of a rotting carcass for more than two miles), human-level hearing, but relatively poor eyesight.

Communication Channels: tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

Brown bears in the wild can live for 20 to 30 years, although most brown bears die in their first few years of life. In captivity, brown bears have been known to live up to 50 years.

Range lifespan
Status: captivity: 50 (high) years.

Typical lifespan
Status: wild: 20 to 30 years.

Average lifespan
Status: captivity: 50.0 years.

Average lifespan
Status: captivity: 47.0 years.

Female brown bears copulate with multiple males during estrus, which lasts 10 to 30 days. Males may fight over females and guard them for 1 to 3 weeks. Female receptivity is probably communicated by scent marking throughout her territory.

Mating System: polygynandrous (promiscuous)

Mating of brown bears takes place from May to July. Fertilized eggs develop to the blastocyt stage, after which implantation in the uterus is delayed. The blastocyt becomes implanted approximately 5 months after mating, usually in November when the female has entered her winter sleep. A 6 to 8 week gestation follows, with births occuring from January to March (usually while the female is still in hibernation). Total gestation time, including pre-implantation, ranges from 180 to 266 days. Females remain in estrus throughout the breeding season until mating occurs and do not ovulate again for at least 2 (usually 3 or 4) years after giving birth. Two to three offspring are generally born per litter.

Brown bears mature sexually between 4-6 years of age, but continue growing until 10-11 years old. Bears have been known to live and reproduce in Yellowstone Park at 25 years of age, and potential lifespan in captivity is as great as 50 years.

Breeding interval: Brown bear females typically breed every 2 to 4 years.

Breeding season: Breeding occurs from May to July.

Range number of offspring: 3 (high) .

Average number of offspring: 2.

Range gestation period: 180 to 266 days.

Range weaning age: 18 to 30 months.

Range time to independence: 2 to 3 years.

Range age at sexual or reproductive maturity (female): 4 to 6 years.

Range age at sexual or reproductive maturity (male): 4 to 6 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; delayed implantation

Average birth mass: 510 g.

Average number of offspring: 2.

Young are born blind, helpless, and naked, weighing only 340 to 680 grams. By 3 months old cubs weigh about 15 kg, by 6 months weight averages 25 kg. Lactation continues for 18 to 30 months, although the cubs are eating a wide variety of foods by about 5 months of age. Cubs remain with the mother until at least their second spring of life (usually until the third or fourth). Male brown bears do not contribute parental care.

Parental Investment: no parental involvement; altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); extended period of juvenile learning

Their conservation status depends on the population. Some populations are clearly endangered, others are not. Brown bear numbers have dropped dramatically since the turn of the century, when settlers and livestock flooded the West, driving these bears out of much of their former range. Brown bears now cling to a mere 2 per cent of their former range. Logging, mining, road construction, resorts, subdivisions, golf courses, etc. have all encroached on suitable bear habitat, resulting in a decrease in bear numbers. Brown bear numbers were estimated at 100,000 in the conterminous United States in the early 1900's, but there are now fewer than 1,000. Brown bears are still fairly common in the mountainous regions of western Canada and Alaska, perhaps numbering about 30,000 individuals. In Eurasia there are an estimated 100,000 brown bears, with about 70,000 of those living in the Soviet Union. However, habitat destruction and persecution threaten brown bears throughout their range. A growing market in bear products for the Asian market, despite a complete lack of evidence that products made from bear parts have any medical value, threatens bear species throughout Eurasia and western North America.

US Federal List: endangered

CITES: appendix i

IUCN Red List of Threatened Species: least concern

Global Short Term Trend: Decline of 10-30%

Comments: Declining in most areas. See Knick and Kasworm (1989), Brannon et al. (1988), Knight et al. (1988), Hayward (1989), and Keating (1989) for discussion of status and mortality patterns in Glacier and Yellowstone parks and in Idaho-Washington-British Columbia. As of the early 1990s, the Yellowstone population was stable, but "optimism over prospects of long-term persistence...does not seem warranted" (Mattson and Reid 1991). Eberhardt et al. (1994) employed data on reproductive and survival rates to conclude that the Yellowstone population may be increasing. USFWS (1990) noted that a record 57 cubs were born in the Yellowstone ecosystem in 1990. Yellowstone population was reported as stable or slightly increasing in the 1980s by Blanchard et al. (1992). A population model presented by Dennis et al. (1991) suggested that the Yellowstone population is doomed to extinction in the long term. Recent trend in Glacier population is debatable. Populations in the Cabinet-Yaak/Selkirk ecosystem appear to be responding to protective measures that reduce mortality. Population trends are inconclusive (USFWS 1999). In the western Carpathians of Europe, excessive killing by human decreased the population to about 40 in 1932; subsequent protection led to an increase to about 700 in the early 1990s (Hartl and Hell 1994).

Brown bears have been long considered the most dangerous animal in North America, although real danger of attack from this animal is often exaggerated. In general, brown bears attempt to avoid human contact and will not attack unless startled at close quarters with young or engrossed in a search for food. They are unpredictable in temperament, however, and often exhibit impulsive and petulant behavior.

Brown bears have been persecuted extensively as predators of domestic livestock, especially cattle and sheep, although their actual impact on the livestock industry is probably negligible.

Negative Impacts: injures humans (bites or stings)

Brown bears have been widely sought as big game trophies and are currently subject to regulated sport hunting throughout much of their range. Once brown bears were used for their meat and hides but these products are not currently in high commercial demand. Some bear body parts (such as gall bladders) bring high prices on the traditional Asian medicine market, although no true medicinal benefit of these parts has ever been documented.

Currently, brown bears help to fuel an ecotourism industry, especially in areas such as Yellowstone National Park, Wyoming and parts of Alaska.

Positive Impacts: body parts are source of valuable material; ecotourism