2. Home ranges and territoriality
Bears are large, generally omnivorous, solitary
carnivores. This indicates large home ranges.
Within any area, numerous brown bears may
conduct daily and seasonal activities without
any major intraspecific conflict (Craighead
1976). Territorial defence of seasonal or
home ranges has not been mentioned, and all
behaviour indicates that defence activities
are largely non-existent. Range peripheries
are definitely not defended, feeding areas
are sometimes temporarily defended, and den
sites are not defended against mature members
of the same sex. Occasionally there may be
a show of dominance at refuse dumps or around
carcasses which is used to temporarily delay
communal feeding. For most of their lives,
brown bears are not territorial and their
individual ranges overlap. Many brown bears
congregate at food sources such as refuse
dumps, carrion, berry patches, pine nut stands
and clover fields. Their daytime beds are
made nearby in dense timber, and numerous
brown bears regularly use the same timbered
retreats simultaneously (Craighead &
Craighead 1972; Craighead 1976; Craighead,
Craighead & Craighead 1985).
Long term movements of some brown bears indicate
that a large proportion of the available
habitat might be covered in a lifetime. Some
mature males may have life-time home ranges
of 2,600 km2 or more. Knight (1980) reports
from U.S.A. that even a female with cubs-of-the-year
may have an annual home range exceeding 518
km2. However, seasonal ranges are localised
and not excessively large. The availability
of food during spring, summer and autumn
tends to limit seasonal range size more than
any other factor.
Roth (1983) fitted four brown bears with
radio collars in the Italian Alps and in
Pritvice National Park, Yugoslavia (former).
He found home ranges between 57 km2 and 74
km2 in summer-autumn whereas in November
the ranges were between 4 and 12 km2. The
bears made "excursions" lasting
3-15 days which took them more than 5 km
beyond the boundary of their core areas on
an average of 36 day intervals. Judd and
Knight (1980) reported minimum home ranges
were between 26 and 741 km2 in Yellowstone
National Park (USA) . The largest home range
was occupied by an adult female accompanied
by a cub-of-the-year.
Some authors (Berns, Atwell & Boone 1980,
Knight 1980, Knight & Eberhardt 1984)
suggest that the large variation in brown
bear home ranges found by different researchers
can probably be explained by wide differences
in habitats and the availability of alternative
food resources. Some major foods fluctuate
between extremes of abundance, and brown
bears must substitute for scarce items. A
particularly favoured site under periods
of average or greater food supply may attract
and serve several bears. During periods of
food scarcity, bears probably take longer
foraging journeys that carry them beyond
their "average" home ranges.
BIBLIOGRAPHY
Berns, V.D., Atwell, G.C. & Boone, D.L.
(1980) Brown bear movements and habitat use
at Karluk Lake, Kodiak Island. Bears-Their
biology and management. (Eds. C.J. Martinka
& K.L. McArthur). Bear Biology Association
Conference Series No 3. Washington D.C.,
pp. 291-296.
Craighead, F.C.Jr. & Craighead, J.J.
(1972) Data of grizzly bear dening activities
and behaviour obtained by using wildlife
telemetry. IUCN Publications (New Series)
No 23, pp. 84-106.
Craighead, F.C.Jr. (1976) Grizzly bear ranges
and movement as determined by radiotracking.
Bears-Their biology and management. (Eds
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IUCN, Morges, Switzerland, New Series Publication
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Craighead, J.J., Craighead, F.L. & Craighead,
D.J. (1985) Using satellites to evaluate
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Judd S.L. & Knight, R.R. (1980) Movements
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the Yellowstone area. Bears-Their biology
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McArthur). Bear Biology Association Conference
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Knight, R.R. (1980) Biological considerations
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Knight, R.R. & Eberhardt, L.L. (1984)
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Roth, H.U. (1983) Home ranges and movement
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