Bears are solitary by nature, unless it is the mating season or they
have cubs. Bears do congregate in areas of high food density, such as
oak groves or berry patches. These groupings happen more because one
bear cannot defend such a rich food source from competitors than because
they enjoy the company. A group of bears is properly called a "sleuth"
or a "sloth", derived from Middle English for "slow", although the reason
for the reference is unknown.
In general, bears are not territorial in that they do not defend a
specific area from intrusion by other bears. The area they wander in
search of food, water and adequate cover is called a home range. The
size of a home range may vary each season and year depending on food
availability, the sex, age, and reproductive status of the bear, and
population density. During major droughts and mast failures, bears will
explore new areas in search of food. In Florida, male bears typically
have home ranges of 50 to 120 square miles; female ranges generally
are 10 to 25 square miles.
Black bears have decent eyesight, possibly as good as humans, and recent
research has found that they have color vision. They have acute hearing
and an excellent sense of smell. Their rumored poor vision may be due
to their reliance on their sense of smell, as well as behavior.
When black bears see humans, they often do a lot of sniffing, and may
stand up. This is not a sign of aggression, it helps them to catch scent
and to get a better look. Combined with their relatively small eyes,
people may interpret these actions as signs of trouble seeing us even
though we clearly see them. Additionally, bears display "threat-averting
behavior" by avoiding direct eye contact. This means that when a bear
sees a person (or another bear) and decides to ignore you instead of
running, it tries to avoid looking directly at the person. Instead,
they will glance quickly to see where you are and turn away. People
may interpret this to mean that the bear looked their way but did not
Bears are believed to have the uncanny ability to navigate homeward
from unfamiliar areas, called "homing." During a Minnesota berry-crop
failure, one male black bear wandered a record 125 miles into a new
area to forage. Nuisance bears have been able to return to their home
range after being drugged and transported up to 168 miles away. How
they do this is unknown, but apparently there is a limit, because bears
transported 870 miles away (from Minnesota to Arkansas) moved in random
directions after their release.
Bears are quiet creatures, but occasionally they make sounds to communicate. Cubs bawl
and moan when distressed, and make a sort of
grunting purr when suckling. Sows communicate with their young
by grunts or moans and can send their cubs up trees for safety, or have
them follow her. An aggressive
bear does not growl like a dog. Instead, they will stare, protrude their lower lip,
their ears. If the source of their unease remains, they may slap
the ground, "huff"
or "blow", and snap or "gnash" their jaws. If these behaviors don't scare
off the other bear, the bear may charge.
bears bite and claw marks onto trees between 5 and 7 feet high, both
conifers and hardwoods, but the reason for such markings is unknown.
Marks occur along defined game trails, especially at ridge lines in
mountainous areas, with the mark facing the trail. Often bears rub against
these trees as well. Four untested theories are:
1) The marks are related to male dominance hierarchies,
2) marks communicate breeding status to ensure males and females are
synchronized successfully for breeding,
3) marking territory boundaries among females in certain populations
that show territorial defense behavior, and
4) marks may serve to help orient bears in new or little used areas
(marking increases when a bear enters a new areas).
Most likely there are several reasons why black bears mark trees.