CONTENTS

Living OrganismsAnimalia / Craniata / Mammalia / Carnivora / Ursidae / Ursus / Species

Ursus arctos - Brown bear (Click photographs/illustrations for full picture & further details)

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INDEX - INFORMATION AVAILABLE

GENERAL & REFERENCES

APPEARANCE / MORPHOLOGY

LIFE STAGES / NATURAL DIET / PHYSIOLOGY

BEHAVIOUR

HABITAT & RANGE

CONSERVATION

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General and References

Alternative Names (Synonyms)

  • Alternative species names (the second part of the binomial species names): [Genus] absarokus, [Genus] alascensis, [Genus], [Genus] albus, [Genus] alexandrae, [Genus] alpinus, [Genus] andersoni, [Genus] annulatus, [Genus] apache, [Genus] argenteus, [Genus] arizonae, [Genus] atnarko, [Genus] aureus, [Genus], [Genus] badius, [Genus] baikalensis, [Genus] bairdi, [Genus] beringiana, [Genus] bisonophagus, [Genus] bosniensis, [Genus] brunneus, [Genus] cadaverinus, [Genus] californicus, [Genus] canadensis, [Genus] candescens, [Genus] caucasicus, [Genus] caurinus, [Genus] cavifrons, [Genus] chelan, [Genus] chelidonias, [Genus] cinereus, [Genus] collaris, [Genus] colusus, [Genus] crassodon, [Genus] crassus, [Genus] cressonus, [Genus] crowtheri, [Genus] dalli, [Genus] dusorgus, [Genus] eltonclarki, [Genus] ereunetes, [Genus] eulophus, [Genus] euryrhinus, [Genus] eversmanni, [Genus] eximius, [Genus] falciger, [Genus] ferox, [Genus] formicarius, [Genus] fuscus, [Genus] grandis, [Genus] griseus, [Genus] gyas, [Genus] henshawi, [Genus] holzworthi, [Genus] hoots, [Genus] horriaeus, [Genus] horribilis, [Genus] hylodromus, [Genus] idahoensis, [Genus] imperator, [Genus] impiger, [Genus] innuitus, [Genus] inopinatus, [Genus] insularis, [Genus] internationalis, [Genus] isabellinus, [Genus] jeniseensis, [Genus] kadiaki, [Genus] kenaiensis, [Genus] kennerleyi, [Genus] kidderi, [Genus] klamathensis, [Genus] kluane, [Genus] kodiaki, [Genus] kolymensis, [Genus] kwakiutl, [Genus] lagomyiarius, [Genus] lasiotus, [Genus] lasistanicus, [Genus] latifrons, [Genus] leuconyx, [Genus] macfarlani, [Genus] machetes, [Genus] macrodon, [Genus] magister, [Genus] major, [Genus] mandchuricus, [Genus] marsicanus, [Genus] melanarctos, [Genus] mendocinensis, [Genus] meridionalis, [Genus] merriamii, [Genus] middendorffi, [Genus] minor, [Genus] mirabilis, [Genus] mirus, [Genus] myrmephagus, [Genus] navaho, [Genus] neglectus, [Genus] nelsoni, [Genus] niger, [Genus] normalis, [Genus] nortoni, [Genus] norvegicus, [Genus] nuchek, [Genus] ophrus, [Genus] orgiloides, [Genus] orgilos, [Genus] oribasus, [Genus] pallasi, [Genus] pamirensis, [Genus] pellyensis, [Genus] persicus, [Genus] perturbans, [Genus] pervagor, [Genus] phaeonyx, [Genus] piscator, [Genus] planiceps, [Genus] polonicus, [Genus], [Genus] ruinosus, [Genus] pulchellus, [Genus] pyrenaicus, [Genus] richardsoni, [Genus] rogersi, [Genus] rossicus, [Genus] rufus, [Genus] rungiusi, [Genus] russelli, [Genus] sagittalis, [Genus] scandinavicus, [Genus] schmitzi, [Genus] selkirki, [Genus] shanorum, [Genus] sheldoni, [Genus] shirasi, [Genus] shoshone, [Genus] sibiricus, [Genus] sitkeenensis, [Genus] sitkensis, [Genus] smirnovi, [Genus] stenorostris, [Genus] syriacus, [Genus] tahltanicus, [Genus] texensis, [Genus] toklat, [Genus] townsendi, [Genus] tularensis, [Genus] tundrensis, [Genus] ursus, [Genus] utahensis, [Genus] warburtoni, [Genus] washake, [Genus] yesoensis. (B141)
  • Ursus horribilis - Grizzly bear (North America) (B51)
  • Ursus arctos arctos - Eurasian brown bear (B285.w4)
  • Ursus arctos horribilis - Grizzly bear (B285.w4)
  • Ursus arctos middendorffi - Kodiak bear (B285.w4)
  • Ursus arctos isabellinus (Asian race)
  • Ursus arctos marsicanus (Abruzzo race) (B422.w14)
  • Ours brun (French) (B144)
  • Braunbär (German) (B144)
  • Barf ka rinch (Hindi) (B392.8.w8)
  • Lal bhalu (Hindi) (B392.8.w8)
  • Safed bhalu (Hindi) (B392.8.w8)
  • Siala reech (Hindi) (B392.8.w8)
  • Haput (Kashmir) (B392.8.w8)
  • Drengmo (Baltistan) (B392.8.w8)
  • Drin mor (Ladak) (B392.8.w8)
  • Dub (Nepali) (B392.8.w8)
  • Red bear (B392.8.w8)
  • Grizzly (D243)
  • Grizzly bear - usually for those in the interior of North America. (D243)
  • Griz (D243)
  • Mazaalai (Mongolian) (B442.7.w7d)
  • Roach-back (D243)
  • Silver-tip (D243)
  • Range bear (D243)
  • Great white bear (D243)
  • Old Ephraim (D243)
  • Moccasin Joe (D243)
  • Alaskan Brown Bear - Ursus arctos middendorffi (B180.w3)
  • Kodiak bear (B180.w3)
  • Red bear (B425)
  • Snow bear (B425)

Recognised subspecies include: [1993](D243)

  • Ursus arctos alascensis Merriam, 1896. Type locality "Unalaklil, Alaska."
  • Ursus arctos arctos Linnaeus, 1958. Type locality "Sweden."
  • Ursus arctos beringianus Middendorff, 1853. Type locality "Great Shantar Island, Sea of Okhotsk."
  • Ursus arctos californicus Merriam, 1896. Type locality "Monterey, California."
  • Ursus arctos collaris Cuvier and Geoffroy, 1824. Type locality "Siberia."
  • Ursus arctos dalli Merriam, 1896. Type locality "Yakutat Bay (NW side), Alaska."
  • Ursus arctos gyas Merriam, 1896. Type locality "Pavlof Bay, Alaska Peninsula, Alaska."
  • Ursus arctos horribilis Ord, 1815. Type locality "Missouri River, a little above mouth of Poplar River, northeastern Montana."
  • Ursus arctos isabellinus Horsfield, 1826. Type locality "mountains of Nepal."
  • Ursus arctos lasiotus Gray, 1867. Type locality "interior of northern China."
  • Ursus arctos middendorffi Merriam, 1896. Type locality "Kodiak Island, Alaska."
  • Ursus arctos pruinosus Blyth, 1954. Type locality "Lhasa, Tibet, China."
  • Ursus arctos sitkensis Merriam, 1896. Type locality "near Sitka, Alaska."
  • Ursus arctos stikeenensis Merriam, 1914. Type locality "Tatletuey Lake, near head of Skeena River, northern British Columbia, Canada."
  • Ursus arctos syriacus Hemprich and Ehrenberg, 1828. Type locality "near Bischerre village, Mt. Makel, Lebanon."

Names for new-borns / juveniles

  • Cub
  • Cub-of-the-year (COY)
  • Yearling
  • Two-year-old

Names for males

Boar

Names for females

Sow

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General Appearance

Adult:

"Bears have a big head; a large, heavily build body; short, powerful limbs; a short tail; and small eyes. The ears are small, rounded, and erect." (B147)

  • Bears are strongly built, with a broad, longish head bearing short round ears and relatively small eyes. The lips are protrusible, the molars are broad and nearly flat. They have a heavy body and a very short tail. They are plantigrade, with five toes, approximately equal in length, to each paw; the paws are wider than those of canids (Canidae - Dogs, foxes (Family)), and the curved, non-retractile claws are longer and stronger. (B144, B288, B424)
  • The brown bear has a prominent muscular hump on the shoulders and a dished facial profile. The claws of the front feet are particularly long, about twice the length of those on the hind feet. These bears lack any pale marking on the chest or around the eyes. The outer pair of incisors are larger than the two inner pairs. The width of the palate between the first and second molars is less than the combined length of these two molars. The first mandibular molar has a length always >20.4 mm and a width >10.5 mm, while the second maxillary molar always has a crown length >31 mm. (B180.w3, B421.w1, B490.26.w26, D243)

Newborn:

Similar Species

Other bears, Ursidae - Bears (Family)
  • Distinguished from Ursus americanus - American black bear by the prominent hump on the shoulders, a dished rather than straight face profile, longer claws and a longer coat, also the larger size of adults. (B147, B180.w3, B285.w4)
    • The outer pair of incisors is larger than the two inner pairs, while in Ursus americanus - American black bear the three pairs of upper incisors are of approximately equal size. (B180.w2, B180.w3)
    • The first mandibular molar has a length always >20.4 mm and a width >10.5 mm, while the second maxillary molar always has a crown length >31 mm and usually >38 mm; these features can be used to distinguish this species from Ursus americanus - American black bear. (B490.26.w26, D243)
  • Distinguished from Ursus maritimus - Polar bear by the brown, not white, coat, the prominent break to the curve of the head profile and conspicuous ears. The width of the palate between the first and second molars is less, not greater, than the combined length of these two molars. (B421.w1)
  • Distinguished from Ursus thibetanus - Asiatic black bear by being generally larger, with a heavier build and with longer limbs, its brown coat and lack of the white "V" on the chest, the presence of a conspicuous hump on the shoulders but lack of longer hairs on the neck and fringing the cheeks, and smaller ears, without long hairs. (B392.8.w8, B425, D243)

Sexual Dimorphism

  • Males are larger than females in all the bears. (B422.w14)
  • Male bears are about 20% larger than female bears (on average). (B147)

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References

Species Authors & Referees

Editor: Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)

Referees: Ellen Dierenfeld (V.w16), Djuro Huber (V.w101), Chuck Schwartz (V.w105)

ORGANISATIONS

ELECTRONIC LIBRARY
(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

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Husbandry Information

Notes

  • Bears are large, strong mammals, adapted to climbing trees and/or difficult terrain, and with claws adapted for climbing and/or digging. Their ability to climb and to claw open trees should be remembered in designing enclosures. 
  • Bears are intelligent, curious and adaptable. They are predominantly diurnal, as seen in undisturbed habitats in the wild, and are mainly solitary. 
  • The behavioural, social and psychological requirements of bears must be taken into consideration in enclosure design and husbandry.

Management Techniques

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Appearance / Morphology

Measurement & Weight

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

LENGTH

  • Adult: The head and body length varies from 1.0 - 3.0 m (3ft 3 inches to 10 ft). This may be due to both genetic factors and nutrition.
  • Newborns: Newborn cubs are about 203 - 280 mm (8 - 11 inches) long.

HEIGHT

  • Adults and sub-adults: Shoulder height is 0.9 - 1.5 m (3 - 4.9 ft).
  • Juveniles: --

WEIGHT

  • Adult: The size and weight of these bears varies considerably between populations; in any given population, males average heavier than females. The heaviest brown bears have been recorded from populations with access to salmon in coastal Alaska. While individuals have been weighed at more that 1,000 lb (>454 kg), most are much lighter than this. Average weights are probably closer to 200 kg (450 lb) for males and 135 kg (300 lb) for females; however in some areas they are much smaller: in some populations in southern Europe average weight is as low as 70 kg, and in Jasper National Park, Alberta, Canada, average weights were 92 kg for males, 55 kg for females. This wide variation may be due to both genetic factors and nutrition. Weight also shows large seasonal fluctuations; brown bears gain weight rapidly during late summer and autumn (fall), reach their maximum mass just before denning, then lose weight (up to 40% of total mass for females) over the winter hibernation.
  • Newborns: Cubs weigh less than 1% of maternal weight, about 285 - 600 g (9 oz to 1 lb 5 oz).

GROWTH RATE

  • Growth rate is highly variable depending on food intake. Hand-reared cubs have variously reached between about 1.7 and 2.5 kg by one month, 4.3 - 6.4 kg by two months, 7.4 - 8.5 kg by three months, 20 kg by four months and as much as 50 kg at seven months. Wild cubs may reach 15 kg at three months. In the wild, young-of-the-year may range from 2.0 - 27 kg and yearlings from 9 - 37 kg. Growth may continue after puberty (four to six years), even to 10-11 years of age in southern Alaska.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Appearance-Morphology- Measurement and Weight (Literature Reports)

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Head and Neck

EDITORIAL SUMMARY

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The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

GENERAL HEAD STRUCTURE:
Adult:
The head is large, with a dished face, short, rounded ears and vestigial vibrissae. The lips are mobile and protrusible, being free from the gums. The skull is massive and the tympanic bullae are not inflated.
Newborn: The ears of newborn cubs are hairless and closed, lying pointing towards the back of the head. The skull, which is circular in the newborn cub, gradually lengthens.

DENTITION:
Adult:
The dental formula is i 3/3, c 1/1, pm 4/4, m 2/3 x2 = 42. The incisors are unspecialised, the canine teeth are long. The first three premolars are reduced or lost. The molars have broad, flat crowns and there are no carnassials.

EYES:
Adult:
The eyes are relatively small. The nictitating membrane is well developed.
Newborn:
Newborn cubs have closed eyes.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Appearance-Morphology- Head and Neck (Literature Reports)

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Legs, Spine and Tracks

EDITORIAL SUMMARY

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The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • The brown bear has powerful legs, five digits on each foot and long, strong, curved claws (those of the front feet may be nearly 10 cm/four inches long) which are usually white to horn-coloured. The soles of the feet are hairy. 
  • The forefoot print may be 175 - 200 mm wide (7 - 8") and half that in length. The hindfoot print may reach 250 - 300 mm long (10 - 12") and 175 - 200 mm wide (7 - 8"). Prints left in soft mud can be larger.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Appearance-Morphology- Legs, Spine and Tracks (Literature Reports)

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Tail

EDITORIAL SUMMARY

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The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • The tail is short, about 60 - 210 mm (2.3 - 8.3 inches).

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Appearance-Morphology-Tail (Literature Reports)

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Skin / Coat / Pelage

EDITORIAL SUMMARY

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The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

Adult: The fur is variable in colour, from blond or creamy tan through gold, grey, silver, cinnamon, light yellowish brown, reddish brown and dark brown to nearly black. There are geographical variations in the normal coat colour. In Eurasia, western bears are generally paler and eastern bears darker. In North America, grizzled bears are common in the Rocky Mountains for example, while Alaskan and Kodiak bears are uniform in colour. The coat of an individual bear may change colour during the year, with the new coat in summer a dark rich brown, while the worn coat becomes tawny or reddish brown. Guard hairs may have a white or silver tip and a white subterminal band, giving a grizzled or frosted appearance. The pelage includes a dense inner fur layer and outer guard hairs. The winter fur is thicker and coarser than the summer fur and appears shaggy. During summer the old inner fur and guard hairs are shed; by autumn there is a fully developed coat, with guard hairs about 10 cm long, underfur about 8 cm long. 

Adult Colour variations: Some adults have a pale band around the thorax behind the front legs and some have a pale band round the neck, in front of the shoulders.

Newborn/Juvenile: Cubs have short grey-brown hair. There may be a pale band round the neck.

Dermis, Subdermis and Epidermis: The skin is thick, particularly over the foreparts of the bear.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Appearance- Morphology- Skin-Coat-Pelage (Literature Reports)

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Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Bears do not have any major anatomical specialisations.

Further information is available within this section on the musculo-skeletal system, male and female reproductive organs, gastrointestinal, urinary and hepatic systems.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Detailed Anatomy Notes (Literature Reports)

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Life Stages / Natural Diet / Physiology

Life Stages

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

BREEDING SEASON: The mating season may occur between late April and early August. In North America it is mainly mid-May to mid-July, in India May or June, in western Europe, July. Autumn (mid-September to early October) courtship and mating has been seen, rarely, in British Columbia, Canada.

OESTRUS/OVULATION: Oestrus lasts 10 to 30 days in mature females. Females coming into oestrus for the first time have a short oestrus, less than one week, which does not result in pregnancy.

GESTATION/PREGNANCY: Gestation lasts 6.5 - 8.6 months. Initially, the fertilised ova develop only to the 200-cell blastocyst stage. Development then stops until late October to November, when implantation occurs and development continues, this active gestation period lasting six to eight weeks.

PARTURITION/BIRTH: Cubs are born while the female is hibernating, in January to March (December to January in India).

NEONATAL/DEVELOPMENT: Brown bear cubs are altricial, with only a fine hair covering at birth and closed eyes. The eyes open at about 20 - 35 days and tooth eruption starts at 35 - 40 days. They start walking at 45 - 55 days and by 75 - 90 days they follow their dam and are starting to eat solid food. Cubs remain with their mother at least to their second and often to their third or fourth spring, but may be able to survive alone from about seven months if orphaned. Growth rate is highly variable depending on food intake. Hand-reared cubs have variously reached between about 1.7 and 2.5 kg by one month, 4.3 - 6.4 kg by two months, 7.4 - 8.5 kg by three months, 20 kg by four months and as much as 50 kg at seven months. Wild cubs may reach 15 kg at three months. In the wild, young-of-the-year may range from 2.0 - 27 kg and yearlings from 9 - 37 kg.

LITTER SIZE: A litter contains one to four cubs, but two or three is usual. Observed larger litters (five or six cubs) may be due to cub adoption. Mean litter size in North America varies from 1.70 - 2.66.

TIME BETWEEN LITTERS / LITTERS PER YEAR: Litters are born at least two years apart, but three or four years is more usual and the interval may reach six years in some areas.

LACTATION / MILK PRODUCTION: Lactation may last 1.5 to 2.5 years or even longer.

SEXUAL MATURITY: Sexual maturity varies between populations, with first litters born to females as young as three years (rarely) up to as old as nine or ten years. Males in the continental USA reach sexual maturity at about 5.5 years, those in Alaska at about 4.5 years.

MALE SEASONAL VARIATION: Male brown bears show distinct seasonal changes in reproductive function. The testes reach their maximum size and weight during the breeding season, regress following the breeding season and recrudesce in the late hibernation period. 

LONGEVITY / MORTALITY: Mortality is highest in cubs of the year; this may be 50%, generally involves whole litters, and often occurs during denning or in the first month after emergence, probably due to malnutrition. Mortality reduces to 10 - 15% for cubs during their second and third years while still with their mother, increases again in weaned cubs which have separated from their mothers then decreases again in adults. Causes of mortality may include severe winters, malnutrition, senility, disease, infanticide, cannibalism and complications of injury after goring by ungulates. Brown bears potentially may live to 25 or 30 years in the wild (36 has been recorded, although the average is much lower) and the record for a brown bear in a zoo is 47 years.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Life Stages (Literature Reports)

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Natural Diet

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

NATURAL DIET:

  • Brown bears are omnivorous. The diet varies with area and season, depending on availability. Vegetable foods such as grass, sedges, roots, bulbs and mosses may be important in spring, then succulent forbs, with berries, bulbs and tubers becoming important in summer, and berries, fruits, nuts, acorns and pine seeds in fall. Honey, grain and fungi are also eaten.
  • Considerable animal foods may be eaten. Carcasses of large ungulates may be important in spring. Aggregations of insects may be eaten, salmon are an important seasonal item at salmon rivers. Ground-breeding birds, rodents and various ungulates are eaten, also in some areas Ursus americanus - American black bear; cannibalism also occurs.

QUANTITY EATEN: Little has been published on the amounts eaten by brown bears. A study in the Yukon noted that hyperphagic brown bears ate more than 200,000 berries (of 0.2 g each) per day while gaining weight at 0.4-0.64 kg per day.

STUDY METHODS: Studies have involved scat analysis, examination of feeding sites, direct observation, and stable isotope analysis.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Natural Diet (Literature Reports)

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Hibernation / Aestivation

EDITORIAL SUMMARY The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Brown bears hibernate during the winter period when food is unavailable or of greatly reduced availability, entering their dens in September to December and emerging in March to May. Hibernation lasts three to seven months.
  • In some areas it appears all bears enter their dens at about the same time. Other studies have found that pregnant females entered their dens earlier than other bears.
  • Individuals which have fed sufficiently, laying down enough fat, den earlier than those which do not have sufficient fat reserves; these stay active and feeding until forced to den by low temperatures and snowstorms.
  • In spring, adult males and females leave their dens first, then females with yearlings and last females with cubs.
  • During hibernation, body temperature is reduced by about 4 - 5 °C, the respiratory rate decreases to about one breath a minute and the heart rate to 8 - 10 bpm. Blood is redistributed, going mainly to the heart, lungs and brain. During hibernation the bears do not eat, drink, defecate or urinate. water needs are satisfied by metabolic water from fat. Blood total protein, uric acid and urea remain constant; the creatinine concentration rises to about twice normal. Males lose about 22% of their autumn mass over the winter hibernation, females about 40%, due to the demands of reproduction.
  • For information on den sites and designs see: Brown bear Ursus arctos - Nests - Burrows - Shelters (Literature Reports)

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Hibernation - Aestivation (Literature Reports)

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Haematology / Biochemistry

EDITORIAL SUMMARY The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

HAEMATOLOGY:

BIOCHEMISTRY:

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Literature Reports: Brown bear - Ursus arctos - Haematology - Biochemistry Notes

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Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

METABOLISM (TEMPERATURE): The normal rectal temperature of adult bears is 36.5 - 38.5 °C (97.7 - 101.3 °F)

RESPIRATORY SYSTEM (RESPIRATION): The normal respiratory rate is 15 - 30 breaths per minute. During hibernation this may decrease to as low as one breath per minute.

CIRCULATORY SYSTEM (PULSE/HEART RATE): The normal heart rate in active brown bears is 40 - 50 bpm, or higher in cubs. During hibernation it decreases to about 8 - 10 bpm. 

HAEMATOLOGY / BIOCHEMISTRY: Values are similar to those of the domestic dog.

GASTROINTESTINAL SYSTEM (FAECES AND GUT MOTILITY): Scats (faeces) are usually cylindrical, but may be rounded or massed. They may be more than 50 mm (2 in) wide. Animal hair, husks or vegetable fibres may be visible. Food passes through the short gastro-intestinal system quickly.

URINARY SYSTEM (URINE): --

CHROMOSOMES: 2n = 74 Chromosomes.

MUSCULO-SKELETAL SYSTEM: --

SPECIAL SENSES AND VOCALISATIONS: Brown bears have quite good vision, but better hearing and a superb sense of smell. All these senses are used in communication. Vocalisations include distress calls from both adults in pain and from hurt, hungry, separated or cold cubs, huffs and snorts of apprehension, growls and roars in aggression and chuffing as a close contact call.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Detailed Physiology Notes (Literature Reports)

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Behaviour

Feeding Behaviour

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Bears take fruit, berries, nuts and grain from the ground, tear up berry patches, overturn rocks and tear up rotting logs to get insects, walk through standing grain crops and draw the grain towards them with their forepaws. 
  • As well as eating carrion, they actively prey on a variety of ungulates, particularly calves, but also adults. Calves and yearlings rather than adults of livestock are taken most commonly, and in forests rather than on open range.
  • During the salmon run they may gorge and eat only a bite of each fish caught. The method used for catching fish - teeth, paws, or teeth and paws - is learned by cubs from their mother. 
  • Brown bears also dig for ground-dwelling rodents, and can get substantial amounts of food in this manner.
  • Brown bears sometimes cache carcasses of prey, remaining near the cache. Caching may reduce decomposition and hide the carcass from competitors.

Further information on diet is provided in Brown bear Ursus arctos - Natural Diet (Literature Reports)

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Feeding Behaviour (Literature Reports)

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Parental Behaviour

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Females nurse and protect their cubs, and remain in their winter dens until the cubs are capable of following. 
  • In the first weeks out of the den, the mother travels less far than usual and teaches the following cubs to climb and to search for food. 
  • Cub adoption and mixing of litters occurs occasionally
  • In the first winter after birth the cubs den with their mother. The following year, if pregnant, she dens alone.
  • Cubs remain with their mother for two to three years, occasionally into a fourth year. The mother chases her cubs away when she comes into oestrus.
  • Instances of abandonment of a single cub (and of two cubs associated with disturbance) have been recorded.
  • Males play no part in cub rearing.

Further information on reproduction is provided in Brown bear Ursus arctos - Life Stages (Literature Reports)

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Parental Behaviour (Literature Reports)

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Social Behaviour / Territoriality / Predation / Learning

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Home range varies depending on the age, sex and social status of the bear, its condition, foraging habits, food availability, also topography, availability of cover, day beds and dens, and proximity to mates. Adult males have larger home ranges than do adult females. On Kodiak Island, home ranges may be only 24 kmē for males and 12 kmē for females, while on the mainland, average ranges for males vary from 200 - 2,000 sq. km (80 - 800 sq. miles), and for females 100 - 1,000 sq. km (40 - 400 sq miles).
  • Population densities vary greatly depending on latitude and habitat, for example as high as one bear per 1.5-4 kmē on Kodiak Island and 1 per 10 kmē for Gorski Kotar, Yugoslavia, but one per 23 - 27 kmē (one per 9 - 10 square miles) in southwestern Yukon and 0.6 to 7.9 per 1,000 kmē in Norway.
  • Brown bears are non-territorial; there is extensive overlap between home ranges and no evidence of territorial defence. Large numbers of bears may gather at rich food sources.
  • Young females tend to stay near their mother's home range, while males move away.
  • Bears can be tracked using GPS and/or conventional VHF radio-collars. Adequate sample sizes are required for accurate, precise estimates of home range sizes.
  • Bears may show "defensive threat" behaviour. 
  • Brown bears are generally considered solitary except for females with cubs, and pairs which may form briefly in the mating season. This may be an over-simplification. Littermates may continue to associate with one another for as long as 4.5 years, playing and feeding together. In general, spacing and mutual avoidance reduces aggressive encounters between individuals. Adult males are aggressive and intolerant of one another during the mating season. At seasonal high concentrations of food, large numbers of bears may aggregate. Dominance hierarchies form in these situations; dominant adult males are highest ranking, females with cubs are below these, and subadults are below these. Fights sometimes occur and occasionally the smaller bear in such a fight is killed. Females with young avoid crowded areas, since aggressive dominant males may attack cubs and even the female. Females defending cubs may attack and even occasionally kill males which approach too closely.
  • Brown bears compete with Ursus americanus - American black bear where their ranges overlap; they are dominant to black bears and may kill and eat them. Hybrids have been reported in captivity. Little is known about the interactions of brown bears with Ursus maritimus - Polar bears where they share ranges, but one wild hybrid has been confirmed as well as zoo hybrids. Other competitors include Puma concolor - Puma, Lynx rufus - Bobcat, Canis lupus - Wolf, wolverine (Gulo gulo (Mustelidae - Weasels (Family))) and foxes (Vulpes - (Genus) and Alopex - (Genus)). Brown bears hunt a variety of wild ungulates and various ground-dwelling rodents; they also kill domestic livestock. 
  • These bears generally try to avoid humans. Most attacks on humans have been shown to be provoked by harassment or efforts to shoot the bear. Bears startled close to, particularly if with young, or while feeding, are unpredictable. Siberian and interior North American brown (grizzly) bears can be dangerous, particularly when defending cubs or a carcass. Eastern European bears appear to be more aggressive than Western European bears.
  • There are few predators on brown bears. Attacks by tigers (Panthera tigris (Felidae - Cats (Family))) occur occasionally in the former USSR and predation of a 6 kg cub by a golden eagle has been reported. Large male brown bears in the breeding season may prey on young cubs and even occasionally on females.
  • Brown bears spend the winter hibernating in a den dug in the ground.
  • Young bears learn from their mothers, which improves survival. It has been noted that the ability of brown bears to dig a den increases with experience.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Social Behaviour - Territoriality - Predation - Learning (Literature Reports)

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Sexual Behaviour

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Brown bears are promiscuous, particularly in areas of high density; females may mate with two males in one day and with several males over the breeding season. In lower-density areas, a male may defend a female from other males and the two bears may form a brief pair bond, lasting while the female is in oestrus.
  • The male mounts the female from behind and clasps her with his front legs around her body. The male may remain mounted for 10 - 60 minutes, with periods of thrusting and short rests.
  • Mutual ear chewing and nose sniffing have been observed between a pair of bears after mating.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Sexual Behaviour (Literature Reports)

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Activity Patterns, Self-grooming and Navigation

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

ACTIVITY PATTERNS: Brown bears mainly walk but also gallop and leap. They climb, although adults climb trees less well than do Ursus americanus - American black bear. The front claws are mainly used for digging. These bears are very strong and can drag carcasses weighing more than the bear's own body weight. They stand on their hind legs to see better and to reach food. They swim well.

SELF-GROOMING: Brown bears lick and groom themselves. While moulting, they rub themselves.

CIRCADIAN RHYTHM: Daily patterns of activity vary with area, season and human disturbance. These bears may be crepuscular or nocturnal, but in Alaska may be active through the day. In summer they may forage during the night and rest in the day, but they may be active for much of the day and night in spring, when there is little food available, and in fall (autumn) when maximising food intake. Daily time active may vary from e.g. 14 hours in summer to 20 hours in late fall, with about 80% of active time spent foraging. In Europe, most adult bears are nocturnal, but this is probably a learned behaviour; yearlings show a more diurnal pattern of activity.

SPEED OF MOVEMENT: Brown bears mainly walk, but can gallop.

NAVIGATION: Brown bears appear to have a strong homing instinct; many will return to their home range after translocation.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Activity Patterns, Grooming and Navigation Behaviour (Literature Reports)

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Habitat and Range

General Habitat Type

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Brown bears are found in a wide variety of habitats including tundra, alpine meadows, coastlines, forests, semi-desert and desert areas. 
  • Habitats must provide areas for feeding, sanctuary (cover) and denning, with sufficient habitat diversity to allow flexible responses to environmental changes and, in particular, both a sequence of abundant food resources and alternate foods. There must also be corridors for travel between required areas. 
  • In North America they are found mainly in open areas (but with some dense cover available). In Europe, remaining populations are in mountainous woodlands. In the Himalayas they are found in alpine meadow and sub-alpine scrub above the tree line, sometimes at lower altitudes in remote valleys.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - General Habitat Type (Literature Reports)

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Nests / Burrows / Shelters

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Brown bears dig a winter den in which to hibernate. It is usually just large enough for the bear, or for a female and her offspring, and is lined with dry vegetation - spruce or fir branches, beargrass, leaves, twigs or moss.
  • The den is usually under the roots of a mature tree, or a rock, and may or may not have an entrance tunnel.
  • Construction of dens improves as the bear gets more experienced.
  • A natural cavern may also be used.
  • Dens are sited in areas remote from human disturbance, and may be some distance outside the bear's main home range.
  • The elevation, degree of slope and direction of the den varies with location. In southern areas, dens are on northern slopes to avoid mid-winter thaws which could cause flooding; in areas where this is not a problem, they are on southerly slopes.
  • Day beds are in dense cover, dry and sheltered, close to the bear's feeding area and providing the bear with a good view of the area. They may be about 1.0 - 1.2 m long by 0.76 - 0.9 m wide and 0.22 - 0.3 m deep.
  • For information on hibernation see: Brown bear Ursus arctos - Hibernation - Aestivation (Literature Reports)

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Nests - Burrows - Shelters (Literature Reports)

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Distribution and Movement (Migration etc.)

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • Brown bears have a holarctic distribution, being found in both North America and Eurasia within the coniferous and deciduous forest zones, except for eastern North America, lowland China and most of western Europe (where they have been exterminated). 
  • Brown bears may make seasonal movements associated with food resources, with bears of some populations moving hundreds of kilometres.

(References are available in detailed literature reports below)

Maps of their range are provided in B442 - Bears. Status Survey and Conservation Action Plan - Chapters 5, 6 and 7 [full text provided]

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Distribution & Movement (Literature Reports)

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Conservation

Species variation

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.
  • There is considerable intraspecific variation and as many as 86 subspecies have been listed, but now only a few are recognised. The main subspecies are Ursus arctos arctos - Eurasian brown bear in Eurasia and Ursus arctos horribilis - Grizzly bear in North America. The Kodiak bear Ursus arctos middendorffi is often recognised as a separate North American subspecies.
  • Phylogeny based on mitochondrial DNA studies suggests five clades: Clade I from southern Scandinavia and southern Europe; Clade II from the ABC Islands; Clade III from eastern Europe, Asia and western Alaska; Clade IV from southern Canada and the lower 48 states of the USA; and Clade V from northern Canada and eastern Alaska. In Europe, in most countries only one clade is found but both are present in Romania. Within the western European populations there are three main maternal lineages.

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Species Variation (Literature Reports)

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Conservation Status

EDITORIAL SUMMARY

The following editorial comment summarises detailed information given within the LITERATURE REPORTS. Links to the LITERATURE REPORTS are provided at the bottom of this box.

WILD POPULATION - IMPORTANCE:  The world population may total 200,000 - 250,000, but many populations are small. The largest populations are in Russia (more than 123,800), Alaska (25,000 - 39,100) and Canada (about 25,000), but only about 800 - 1020 in the lower 48 states, less than 25 in each of Spain, France, Italy and Greece, perhaps 25 - 30 in Mongolia and low populations elsewhere in Eurasia.

GENERAL LEGISLATION: Legislation varies widely across countries. In some areas brown bears are totally protected, in others there are various limits on legal hunting and on the extent to which they can be killed to control damage to crops or livestock.

CITES LISTING: The populations of Bhutan, China, Mexico and Mongolia are in Appendix I; all other populations are included in Appendix II.

RED-DATA LIST STATUS: Ursus arctos is listed as Lower Risk (least concern); the subspecies Ursus arctos nelsoni (Mexican brown bear) is classified as extinct.

THREATS: The main threats are excessive legal hunting, poaching for gall bladders and other body parts, habitat disruption and killing of "nuisance" bears.

PEST STATUS / PEST POPULATIONS: Individual brown bears sometimes become pests where they are attracted to human food and garbage, and where they damage agricultural crops or beehives, prey on livestock, or attack humans.

CAPTIVE POPULATIONS: More than 440 brown bears of various subspecies are kept in zoos round the world (based on ISIS data).

TRADE AND USE: --

For more information see: B442: Bears. Status Survey and Conservation Action Plan - full text provided

(References are available in detailed literature reports below)

CLICK THE LINKS FOR Literature Reports Brown bear Ursus arctos - Conservation Status (Literature Reports)

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