KEEPING WARM 
slow or slower than that of most low- 
temperature hibernators. 
Even in hibernation, the captive tele- 
metered bear retained a remnant of its 
day-active schedule. For a portion of 
most days, the bear’s heart speeded up 
to more than forty beats per minute, and 
the animal was wakeful enough to lift its 
head if the room lights were turned on. 
Wild bears in northeastern Minnesota 
also tend to be day active, and most of 
those I visited in dens were wakeful 
enough that they lifted their heads and 
looked at me. Although, in general, they 
seemed less sensitive to danger than 
they had been in summer, some were 
moderately aggressive. A few did not 
wake up even during several minutes of 
gentle prodding and jostling, however. 
In one case, on March 27, 1970, I acci- 
dentally fell on a six-year-old female in 
her den. She didn’t wake up for at least 
eight minutes even though her cub 
bawled loudly and 1 began gently prod- 
ding her. I wondered if the different 
receptions I got from the bears reflected 
differences in their heart rates at the 
times I happened to visit them. On calm 
days I could hear the rapid, strong 
heartbeats of alert bears from the en- 
trances of their dens, but I could not 
hear the soundly sleeping ones. 
On January 8, 1972, I tried to hear 
the heartbeat of a soundly sleeping five- 
year-old female by pressing my ear 
against her chest. 1 could hear nothing. 
Either the heart was beating so weakly 
that I could not hear it or it was beating 
so slowly I didn’t recognize it. After 
about two minutes, though, I suddenly 
heard a strong, rapid heartbeat. The 
bear was waking up. Within a few sec- 
onds she lifted her head as 1 tried to 
squeeze backward through the den en- 
trance. Outside, I could still hear the 
heartbeat, which I timed (after check- 
ing to make sure it wasn’t my own) at 
approximately 175 beats per minute. 
This heart rate during arousal is even 
higher than has been recorded for very 
active bears. 
Research scientists were not the first 
people to look into a bear den. Indians 
noted the locations of dens they found in 
the fall and returned to them in winter 
to kill the bears for food. They respected 
bears and had special ceremonies sur- 
rounding the killing and eating of them. 
Members of the Winnebago Bear Clan 
called the first moon of January the bear 
moon because it is then that the cubs are 
born and then that the bears begin to 
lick their paws. Both observations are 
accurate. The Indians also believed that 
mothers washed their newborn cubs 
with fresh snow. According to a clan 
saying, snow during the bear moon 
meant that another cub had been born 
and that the bears, which had control of 
the weather, were calling for fresh snow 
to wash their young. Mothers do lick 
their newborn cubs, but the use of snow 
has not been documented in modem 
times. 
Bears commonly lick their paws in 
late winter and early spring because 
their calloused foot pads and toe pads 
flake off during hibernation, and the 
newly exposed skin is not yet toughened 
up. Bits of the pads can be found in the 
feces in spring. Primitive people in 
northern latitudes around the world be- 
lieved that bears licked or sucked their 
paws for sustenance in winter. The Win- 
nebago version of this story is that bears 
walk on berries all summer, crushing the 
different kinds into their paws so that in 
winter they can lick their paws and 
obtain the essence of the berries. 
Another story, which has even been 
stated as fact in the scientific literature, 
is that bears eat roughage in the fall to 
scour the digestive tract and form a plug 
in the anus. The plug supposedly keeps 
the bear from eating anything more that 
fall. Actually, there is an anal plug of 
feces (along with some bear hairs and 
bits of nest material), but this forms 
mainly during, not before, hibernation. 
Bears continue to make feces during 
hibernation, even though there is no 
food intake. Feces are composed not 
only of indigestible parts of food but also 
of cells that continually slough off the 
inside of the digestive tract. By spring, 
there is quite an accumulation of feces 
in the colon, and some bears defecate 
portions of this before emerging. In that 
case, the feces are deposited in or just 
outside the entrance to the den, rather 
than in the nest. 
From early fall to late spring most 
black bears lose between 15 and 30 
percent of their body weight. Lactating 
mothers can lose as much as 40 percent. 
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