[music playing]
NARRATOR: When it
comes to hibernating,
it's not all bears
and groundhogs.
Other mammals, amphibians,
birds, and even
insects rest for long periods.
And depending on the
duration and season,
there are different names
for this sedentary state.
The most commonly
known, hibernation,
occurs during the winter.
It's summer counter-part
is called estivation.
Both are an extended
form of torpor.
Torpor is a short-term
state of lowered
metabolic rate and
body temperature,
lasting under 24 hours.
So which animals enter
these dormant periods?
The spadefoot toad
in the Sonoran Desert
estivates through
long dry spells,
sometimes lasting up
to a year underground.
When the first rainfall
arrives, these sleepy diggers
emerge as a group
to eat and mate
before the water evaporates.
The crocodile, however, both
estivates and hibernates
during extreme weather.
These reptiles dig burrows into
the side of riverbanks for use
when temperatures are
either too hot or too cold.
But when it comes
to group torpor,
no one flies above the North
American monarch butterfly.
These monarchs may migrate over
3,000 miles to remote forests
in Mexico, where hundreds
of millions of butterflies
huddle together in trees--
the perfect locale for
isolated hibernation.
Plenty of other animals
take an easier route
to conserve energy.
Primates, like the mouse
lemur and the bush baby,
practice daily torpor.
So do some bats and hedgehogs.
No matter the animal
or style, science
shows that torpor in any form
is different from either sleep
or wakefulness.
And not well understood.
Torpor is still very much
a mystery to scientists
who have a lot more
questions than answers
to why and how it works.
Still, as scientists research
and better understand torpor,
perhaps, they'll be
able to incorporate
benefits from this
state of consciousness
into our own health.
Or at the very least, better
predict whether the groundhog
will see his shadow.
