The Brown bear, Ursus arctos, have several sub-species, Ursus arctos
horribilis, the grizzly bear, and Ursus arctos middendorffi, the Kodiak bear of
the Alaskan islands of Kodiak, Shuyak and Afognak.
Distribution, Population and Range: Of all the eight species of bears, the Brown
bear has the most widespread distribution found throughout most of the Northern
hemisphere. Their preferred habitats include mountain forests, open meadows and
large river valleys. It is estimated that there are currently between 125,000
and 150,000 Brown bears in the world. They are however threatened by development
and have all but been eliminated from much of their natural range. It is
believed that the coniferous forests of Eurasia, in particular Russia, are the
final strong-hold of the Brown bear. Up to 100, 000 of the global population
reside in this region.
In North America the population of Brown bears is declining at an alarming rate
with only 40,000 to 50,000 Brown bears still in existence. They have been
effectively eliminated from 48 US states and remaining populations are
distributed between western Canada and Alaska.
The home range of the Brown bear is dependent upon food availability and
location. To demonstrate this point researchers have discovered that a bear
living in the mountains in Alaska required a 1350 square kilometre range whereas
one residing in a salmon-rich coastal area only required a 27 square kilometre
range.
In general male bears require a home range that is 4-6 times larger than that of
a female. The home range does not consist of a single large area but is
comprised of a series of several food source areas interconnected by travel
lanes. Given the size, home ranges overlap Brown bears rarely defend their
entire home range from other bears.
Physical Characteristics: Whilst of variable dimensions, the average adult Brown
bear stands at 100 centimetres, has a length of 200 centimetres and weighs
between 150 and 375 kilograms. Males may weigh as much as twice the weight of
females and have been recorded up to 680 kilograms!
Brown bears have a stout body, a distinctive muscular shoulder hump, muscular
limbs, a large head, rounded ears and a short tail. They are good runners and
can reach up to 56 kilometres per hour. Brown bears have long front claws up to
10 centimetres in length and are highly adapted to digging.
Diet: Seasonal availability and location are the primary factors determining the
Brown bear’s food source. It has been estimated that up to 75% of the Brown
bear’s diet consists of vegetable matter: berries, flowers, grasses, sedges,
herbs, roots and nuts. The other 25% consists of fish, small mammals, insects,
honey, elk calves and squirrels. Due to their bulk, Brown bears require a large
daily intake and can eat up to 15 kilograms of food if it is available.
Hibernation: During summer and autumn the Brown bear gains as much weight as
possible (up to 18 kilograms per week) in preparation for hibernation during the
winter months. Hibernation is a survival mechanism that allows bears to survive
long periods when food is scarce. Hibernating bears undergo a metabolic
transformation, their body temperature falls, their heart rate drops to 8-12
beats per minute and their metabolism slows by half. During this period the bear
will not pass either urine or faecal matter and whilst this poisonous build up
would kill many other animals, the bear has developed a unique process of
chemically altering waste chemicals and converting them into useable proteins.
During this period all bears lose a great deal of weight, between 15-30% for a
male and up to 40% for a female. The bear is lethargic upon waking but soon
returns to its original foraging pattern.
Family Life: Female Brown bears become sexually mature in their fifth year and
mating occurs between May and July and give birth to between one and four
600-700 gram cubs. As she ages, the number of cubs she produces increases each
year. The mortality rate of cubs within the first year is about 40% with
starvation and predation being the main causes of death. Infanticide also
contributes and mothers never tolerated male bears near her cubs. If they
survive the first year, cubs stay with the mother for the first two and a half
years and their survival is dependent upon the conveyance of skills.
Conservation Status: The Brown bear is listed as Appendix 2 of CITES, which
implies that they can be traded commercially but only if this trade does not
affect the survival of the species. They are also listed in 48 US states as a
threatened species under the Endangered Species Act with the US Fish and
Wildlife Service.
Threats: Habitat loss and hunting are major threats to the survival of the Brown
bear. Recent evidence suggests that as a result of political pressure to
eliminate illegal trade in bear parts, hunting expeditions into the US and
Canada to poach the gall bladder of Brown bears have occurred. (See the
Environmental Investigation Agency report “Why we must kill the trade to save
the bears” at www.eia-international.org).
Free the Bears Fund supports the campaign to ban the grizzly hunt and we urge
you to express your outrage by writing a letter to the Secretary of Agriculture.
References: The above has been prepared by reading the information
provided by Don Middleton on his web-site:
www.naturenet.com/bears and the
Bear Den at www.bearden.org. I am indebted
to the Environmental Investigation Agency (www.eia-international.org)
for information on both the Grizzly bear hunt and the inclusion of Brown bears
in the illegal wildlife trade.
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