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Brown Bear (Ursus arctos) Fact Sheet: Behavior & Ecology

Activity Cycle

(Pasitschniak-Arts 1993) (Garshelis 2009) (Schwartz 2003)

North American Brown Bears mostly diurnal (but active in day and night when food is scarce)

  • Less active in day in areas with high human population

In Europe, mostly nocturnal due to human presence; young bears more active in day (before having negative experiences with humans)

Active at night in summer

Active season is compressed into a 5-7 month period

Often build day beds for resting in hidden places with good visibility near feeding locations (Pasitschniak-Arts 1993)
Have a yearly cycle of four main behavioral and biochemical changes

  • Hibernate in winter; period varies according local climate
    • Farthest north habitats: up to 7 months
    • On Kodiak Island (mild winters) males may not even den
    • If resources are poor before hibernation time, bears may not have enough body fat to den
  • After denning, for 10-14 days in "walking hibernation"
  • Normal activity May - September
  • Fat accumulation in fall season; food intake and weight increases significantly

Territory Size

(McLellan & Hovey 2001) (Pasitschniak-Arts 1993)

Home range size varies mainly with food resources. (Garshelis 2009)

  • Smallest - 200 sq km (77 sq mi) for males, 100 sq km (39 sq mi) for females in coastal area with abundant food
  • Largest - 8,000 sq km ( 3089 sq mi) for males in Arctic tundra
  • Female home range is smaller than male

Other determinants of territory size

  • Age, sex, social status, health
  • Foraging habits
  • Amount of cover, landscape topography, location of sleeping day beds and dens sites
  • Nearness of possible mates

Brown Bears do not defend a territory.

Males and females occupy overlapping home ranges.

Young female disperse to home ranges 9.8 km (6.1 mi) from mother's home range

Males disperse up to 30 km (18.6 mi).

Social Groups

General

  • Females with young = only lasting social bonds
  • On occasion two females with young may associate and share care and nursing of young. (Murie 1985) (Craighead et al 1995)
  • Orphaned cubs not adopted by another female do not survive in wild
    • Need to have at least had a mother for 6 months

 Hierarchy

  • Alpha males dominate
    • Highest ranking males have best feeding sites and feeding times
  • Females with cubs are willing to challenge even an alpha male

Territorial Behavior

 No territory defense, but "personal space" vigorously defended by prompt attack

  • Offending bear uses conciliatory posture, vocalizations to indicate no harm intended
  • Mother bears with young extremely defensive; will even attack and kill a male who comes too close. (Craighead 1979).

Seasonal movements to areas with abundant food and den sites (Garshelis 2009)

  • May resemble a migration as bears travel along established routes
  • May travel 20 km (12 mi) in 12 hours.

Aggression (Craighead et al 1995) (Pasitschniak-Arts 1993)

  • In a study of Grizzly Bears at Yellowstone National Park
    • Females display 7 times more aggressive attacks and threat behaviors towards males than towards females
    • Both male and female bears react aggressively to intrusion into their "personal space"
    • No obvious (to humans) aggression by another bear triggers this response.
  • Male infanticide exists, but is not a significant cause of cub mortality.
  • When fighting, opponents struck in chest and shoulder with paws; bites directed towards head and neck

Social Interactions

Play (Herrero 1985)

  •  Bears of all ages play
    • Chase birds
    • Adults and young deliberately slide and roll down snowy slopes
    • Manipulate objects
  • Young bears wrestle, jump and tumble together

Olfaction

Scent Marking

  • Relies mainly on a sense of smell for information about the environment. (Pasitschniak-Arts 1993)
  • Many researchers think bears do not mark a territory with scats as do many other carnivores. (Weber 1989, Craighead 1979)

Communication

Displays/Visual Signs

  • Raise to full height when threatened
  • Dominance indicated by a full-fronted approach
    • Neck outstretched, ears laid back, canines displayed
  • Subordinance indicated by sideways orientation
    • Head low or turned away or may sit or lie down, or back away

 Vocalization (Pasitschniak-Arts 1993)

  • With an attack (Kurt 1990)
    • A "high-pitched snorting with open lips"
    • A hoarse barking uttered in short bursts
    • Snap jaws together
  • With a threat
    • Growl and roar
  • When wounded or in pain or when hungry, lost, cold
    • Distress calls
  • When contented or friendly, as a greeting, as appeasement, during courtship, between female and young.
    • Chuffing - "popping" noise made with lips and cheeks while exhaling
    • Both sexes and all ages use

Brown Bear audio, provided by BBC.

Hibernation

Denning

  • Dens are excavated by males and females as early as September or immediately before use in November.
  • Dens in dug earth have a tunnel about 4 feet long leading to a chamber 5 feet in diameter (Murie 1981)
    • Some dens have no entrance tunnel. (Garshelis 2009)
  • Onset of hibernation spurred by length of day and often by a snow storm. (Servheen 1993)
  • Rocky Mountains den sites:
    • Have deep snow that doesn't melt in temporary winter thaws
    • Are on steep or moderately steep slopes
    • Females and cubs may be vulnerable to snowmobile disturbance during denning and immediately after denning. (Podruzny et al 2002)
  • In Croatia,
    • Dens built in rock cavities, under tree roots, in hollow trees, on the ground under conifers. (Huber & Roth 1997)
  • In barren-ground habitats of Arctic regions: (McLoughlin 2002)
    • Brown bears dug dens under tall shrubs, using the roots as the den roof
    • Bears carried nesting materials to den
    • Females entered dens earlier than males
    • Both sexes are denning by October
    • Males emerge before females in late April, early May.
  • During denning
    • About 1/3 of females give birth
    • Another 1/3 of denning females are still nursing yearlings (Craighead et al 1995)
  • Adult females remain in a den for at least half the year. (Atkinson & Ramsay 1995) (Folk et al 1976)

Locomotion

(Craighead et al 1995) (Weber 1986)

  • Favored gait is a slow shuffle.
  • Undisturbed bear walks 5.5-6.0 km/hr (3.4-3.7 mi/hr)
  • Adult bear can gallop at over 56 km/hr (35 m/hr) for 3 km (2 mi).
  • Can trot with average speed of 10-12 km/hr (6.2-7.5 mi/hr)
  • Tree-climbing: (Wilson & Mittermeir 2009)
    • All juvenile Brown Bears can climb trees
    • Adults in North America rarely climb trees (Black Bears do climb trees)
    • Adult Brown Bears in Europe and Asia climb trees
  • Often stand while stopped
  • Use trails that are shortest distance between feeding and resting areas
    • May hesitate 20 minutes while assessing an exposed area before entering open space.

Interspecies Interactions

(Murie 1985) (Podruzny et al 1999) (Mowat & Heard 2006)

  • Grizzly bears and Brown Bears naturally adapted to exploiting temporary but abundant food items (Craighead et al 1995)
    • Feasting on whale carcasses or salmon runs are examples
    • Visiting human garbage dumps only an extenstion of this behavior
  • Range overlaps that of American and Asiatic Black Bears (U. americanus, U. thibetanus)
  • May compete with other carnivores for food (Pasitschniak-Arts 1993)
    • Mountain lions
    • Bobcats
    • Lynx
    • Wolves
    • Wolverines
    • Foxes
  • Eagles and ravens attempt to scavenge bears' kills
    • Also may make kills because of bears' attempts to catch small rodents
  • Population densities of Brown Bears in Arctic are greater when they have access to abundant caribou.
  • Observations by Murie (1985) at McKinley National Park:
    • Caribou populations are culled by grizzlys - calves, old, diseased, and remains of wolf-killed carcasses all enrich Grizzly's diets.
    • Moose calves preyed upon by grizzlys; a female moose attacks bears to protect calf
    • Grizzlys rarely have an opportunity to kill Dall Sheep; carcasses of these sheep occasionally add to the grizzly diet
    • Ground squirrels often caught above ground and below, in burrows
      • Considerable effort sometimes required, lasting up to 40 minutes in one observation
  • Whitebark Pine habitat vital to grizzly survival in Yellowstone National Park (Podruzny et al 1999)
    • Habitat serves as refuge.
    • Red Squirrel caches of Whitebark Pine seeds an important grizzly food resource
    • A fungus, the White Pine blister rust, is decimating Whitebark Pine populations in North America.

Active tree climbers

Brown Bear climbing

Image credit: © San Diego Zoo Global. All rights reserved.

Snow

Brown Bear in snow

Brown bears like to slide and roll down snowy slopes.

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Craighead (1979)
Craighead et al (1995)
Garshelis (2009)
Huber & Roth (1997)
Kurt (1990)
McLellan & Hovey (2001)
McLoughlin (2002)
Murie (1985)
Pasitschniak-Arts (1993)
Servheen (1993)
Schwartz (2003)
Weber (1986)
Wilson & Mittermeir (2009)

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