Hi, that’s an excellent question! There are really
2 questions here. Even hibernators don’t
hibernate all winter. They have to wake up several
times during the winter. They may need to wake up
so they can pee. Really. Their bodies may
also have to do some other important things. They
usually stay in their burrows and go right back
Days get shorter in fall. Light and cold tell them
when to start hibernating. I did some experiments
on this with hamsters that hibernate (they
are a bit different from the ones at the pet
store). If I made their room colder and made the
day shorter (by keeping the lights on for a
shorter time), they would hibernate. If I kept the
lights on longer and made the room warmer, they
would wake up.
They would also wake up every few days on their
own. I could tell this when I checked on them.
First I would use a tube to blow on them. If
they were just sleeping, they would squirm around.
If they didn’t move, I would sprinkle oatmeal
flakes on their backs. If they still had oatmeal
on their backs the next day, I knew they had not
moved. If the oatmeal was gone, I knew they had
woken up and eaten the oatmeal, then gone back to
sleep. They usually didn’t stay in hibernation
much longer than a week.
Most hibernators are underground in winter. So
how do they know it’s springtime? They
may feel the temperature go up. Maybe they can
see enough light to tell them that days are
getting longer. They might be running out of fat
and need to wake up and eat. They also might be
getting a signal from the part of their brain that
is like a clock. Usually, they start waking
up more often near the end of winter. The truth
is, no one knows for sure yet. Maybe you will
help find the answer one day.
Thanks for asking,