More on Bears
Black Bear Classification:
All bears belong to the taxonomic
family ursidae, which is comprised
of all eight extant species of bear.
Ursidae is divided into three subfamilies,
which are ursinae, tremarctinae, and
ailuropodinae. Ursinae is the largest
of these subfamilies, containing American
black bears, brown bears (of which
grizzly bears are a subspecies), polar
bears, sloth bears, sun bears, and
Asian black bears.The subfamily tremarctinae,
on the other hand, contains only the
spectacled bear. Ailuropodinae also
contains only one extant species,
the giant panda.
Even though few species of them exist,
and most are endangered, bears are
very widespread, being found in Europe,
Asia, North America, and South America.
The most widespread species of bear
is the brown bear, which can be found
throughout the former three continents.
The bear species residing in the narrowest
range is the spectacled bear, which
populates only the Andean region of
South America, and is the only species
of bear found on that continent. Polar
bears are found only on the Arctic
Sea, and American black bears are
confined to North America; the remaining
four species reside in Asia.
Bears tend to inhabit forests, with
the exception of polar bears, which
live at sea and on sea ice and Arctic
archipelagos. Some bears, especially
the brown bear, may be found in alpine
shrubland or tundra, in which they
may reside either seasonally or permanently.
Asiatic Black Bear
When the climate of many bears' habitats
becomes cold and food becomes scarce, these
species of bear retreat to their dens and
enter a deep state of rest. This habit is
colloquially known as hibernation, though
it is not a true hibernation; bears' breathing,
heart rate, and metabolic rates slow only
a little bit, their body temperatures do
not drop considerably, and they may occasionally
rouse from this state, while true hibernators
experience more significant changes to their
bodily processes and do not rouse from hibernation.
Bears are large creatures with heavy bodies,
long sharp claws, relatively short legs,
and large heads with long, canine teeth.
They range in weight across species, with
the smallest species, the sun bear, weighing
between 100 and 140 lb on average, and the
largest species, the polar bear, weighing
an average of 850-900 lb. The largest individuals,
however, are often brown bears, with some
subspecies weighing up to 1,180 lb on average.
Bears are quadrupedal, meaning they walk
on four legs, but can stand on two legs
and sit as humans do.
Despite their reputation for being voracious
carnivores, bears, with the exception of
polar bears and giant pandas, are usually
omnivorous. (Polar bears are carnivores
relying a diet of mostly on marine mammals,
while giant pandas eat mostly bamboo.) Bears'
diets are determined largely by their environment,
as they will feed on any food source that
is available to them. They use their exceptional
sense of smell to locate food and prey.
Bears are predominantly predators and tend
not to be prey; the only routine natural
predator of adult bears is the tiger, which
inhabits only Asia.