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Denning serves as a way for
bears to not only survive, but successfully produce offspring during the
cold winter months when natural foods are almost nonexistent. While
black bears are often referred to as “hibernating” during the denning
period, this is actually not the case. Rather, bears enter a sleep-like
state referred to as “winter torpor” in which they are fully capable of
moving and even exiting the den. During that time, their metabolism
slows so that all reserve energy is used for basic life functions and
milk production for cubs. This is why fall food abundance prior to
denning, primarily in the form of acorns, is critical for black bears in
the Southern Appalachians.
Timing of den entry varies
considerably and is primarily determined by sex, reproductive condition,
and fall food availability. In Kentucky, females typically enter dens
from mid-November to December. Collectively, female bears den before
males, and pregnant females or those with offspring den before solitary
females. Sometimes older males den for relatively short periods, and
may travel a bit before denning in another location. That is especially
true if there is ready access to garbage or other human-related food
source during the winter months. During poor mast years, however, bears
den later as it takes longer to acquire enough to make through the 3–4
month denning period in which bears do not eat, drink, urinate, or
defecate.
Bears in Kentucky usually den
in rock cavities, hollow trees, or open dens in thick brush piles. Cubs
grow rapidly as their diet consists exclusively of high-calorie and
fat-rich milk provided by the mother’s fat reserve from the previous
winter’s hard mast consumption. Females with offspring generally emerge
from dens in March or April. Females with offspring remain together
throughout the second winter in which they again den as a family unit.
At about 16 months of age the yearling bears disperse soon as the mother
comes into estrus in preparation for the breeding season. |
Photo by Ben Augustine |
