I was watching a Discovery Channel show with my 13 yr old
son, Jason, and we thought we heard them say that bears do not
technically hybernate. Did we hear correctly? If so, what is the
difference between hbernation and what bears do?
During true hibernation the animal's body temperature drops to around 40 d.
f., heart rate and slows to just a few times a minute, and respiration
is very slow. Bears and some other mammals sleep through much of the winter
but with these essential functions slowed only slightly from active state,
and can be easily awakened.
Bears are not true hibernators. Hibernation refers to a state in which the
animal gives up trying to maintain a constant body temperature because it is
"expensive" in terms of the amount of food available to maintain that high
body temperature. Small animals with high metabolic rates such as rodents,
hummingbirds, insectivores, bats, etc. are true hibernators. Their metabolic
rate drops, their body temperature drops almost to the level of the
surroundings and shows little response to external stimuli. These animals
collect and eat a lot of high caloric food (ie, nuts) to store calories to
make it through. Bears are not true hibernators because their body
temperature drops only a few degrees and they show only a moderate drop in
metabolic rate. Females often give birth to cubs during the winter. They
actually are sleeping deeply, but not hibernating.
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Update: June 2012