The North American Black bear, Ursus americanus, is the most numerous of
the bear species and the one most commonly found in close proximity to man.
Despite its name, the Black bear is not always black and many colour gradations,
from cinnamon, beige and blue-white occur across the nation.
Distribution, Population and Range: The North American Black bear is the most
widespread and numerous bear in North America, with numbers estimated between
400,000 and 750,000. The Black bear can be found throughout Canada and the
United States and as far south as Sierra Madre Mountains of north west Mexico.
These bears are to be found in hardwood and coniferous forested areas.
The size of the home range will vary with availability of food and density of
population. In general, females will have a home range which is 6.5 to 26 square
kilometers while males will normally have a home range four times larger at 26
to 124 square kilometers.
Characteristically, a home range does not constitute one large area but rather
is composed of several smaller food source areas connected by travel lanes. Open
areas are usually avoided by Black bears as they prefer wooded cover.
Physical Characteristics: In general, adult Black bears range from 89 to 102 centimeters tall, 140 to 180 centimeters long, and have an extremely variable
weight range from 57 to 270 kilograms. The largest American Black bear to date
weighed at 365 kilograms. In the wild Black bears can live up to 25 years.
Black bears lack the distinct shoulder hump characteristic of the Brown bear and
the claws on the front paws are shorter and curved, being highly adapted to tree
climbing. Whilst possessing a heavy body the Black bear can reach speeds of up
to 40 kilometers an hour over short distances.
Diet: Whilst classified as a carnivore the Black bear has evolved primarily into
a vegetarian and has the dental and digestive structure to match. 75% of their
diet is comprised of vegetable matter including, berries, flowers, grasses and
sedges, herbs, tubers and roots, and nuts, the remaining 25%, carcasses, fish,
small marine animals, ants and other insects, honey, elk and moose calves and a
variety of other small mammals.
Hibernation: Black bears living in areas which experience severe winters
hibernate for between four and seven months, whereas those residing in a more
temperate climate where food is available all year around do not. During summer
and autumn the Black 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 Black bears are sexually mature at 3 to 5 years of age and
mate every alternate year, selecting several different partners throughout the
mating season. In warmer climates mating may occur in May to June yet is delayed
another two months in colder regions. As with other bear species, the Black bear
is capable of delayed implantation.
Born a mere 240-330 grams, the cubs are generally strong enough to venture out
of the den at their mother’s side by five weeks of age. These cubs remain with
the mother for the first year learning how to forage and are driven off only
when the mother is preparing to breed once again. Sometimes young bears will
form temporary communities as they adjust to living alone. Generally, adult
Black bears are solitary animals and are unlikely to be seen together unless
they are mother and cubs.
Conservation Status: The American Black bear is listed on 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.
Threats: Currently listed as safe throughout the majority of their home range
Black bears are still vulnerable to hunting and habitat destruction as a result
of logging. 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 Black bears have occurred. (See the
Environmental Investigation Agency report “Why we must kill the trade to save
the bears” at: www.eia-international.org).
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. We am indebted to the Environmental Investigation Agency (www.eia-international.org) for information on the inclusion of Black bears in the illegal wildlife trade.
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