There are eight
species of bears in the world and three of them can be found in North America:
black bear, polar bear, and grizzly. There have been up to 94 subspecies of
the grizzly described, including the brown bear (Hall 1981 
).
The black bear is the only native wild bear now found in Oregon. Bears walk
on the soles of their feet, called a plantigrade motion, just like humans.
While they reportedly have poor vision (Whitaker 1980 ),
other researchers have stated their eyesight is excellent, even at a distance
of up to 200 or 300 feet (Domico 1988 ).
One thing is certain, their sense of smell is excellent as almost anyone who
has been backpacking can tell you.
Bears enter
a state of dormancy during winter called hibernation. Some investigators,
however, say that bears do not hibernate because their body temperature only
drops a few degrees during its winter siesta. The body temperatures of "true"
hibernators, they say, falls much more dramatically. Nevertheless, many scientists
still refer to the winter dormancy of bears as hibernation (Hellgren et al
1990 ;
Rogers 1987 )
So, how do you answer the question "do bears hibernate?" It is really
a matter of definition and is based on many factors such as blood flow, heart
rate, weight loss, and various other physiological considerations, but all
of these measurements taken together point to a very definite answer of "maybe"
(Pelton 1982 ;
Nowak 1991 ;
Hellgren et al 1990 ;
Rogers 1987 ;
Folk et al 1977 ).