When the cold weather of winter
arrives, Rhode Islanders have the same three choices that wildlife have – they
can migrate south to avoid the cold, continue their lives as usual and do their
best to ignore the cold, or stay inside and hibernate for the winter.
In
the animal world, the nectar- and insect-eating birds choose the first option,
migrating sometimes great distances to wherever their preferred flowers or insect
prey remain active and available. Like skiers and snowboarders, option two is
the choice of coyotes, foxes, weasels and other hardy mammals, who tough it out
through the cold months and may even benefit from the challenging conditions.
While
most Rhode Islanders probably choose to avoid as much outdoor activity as
possible during the winter, preferring instead to hibernate in their
well-heated homes, few animals in our area make that choice. Woodchucks and
some types of bats may be the only species to undergo the physiologically
challenging process of hibernation.
According
to wildlife biologist Pete August, a professor at the University of Rhode
Island, hibernation is a state of inactivity that, unlike sleeping, involves a dramatic
reduction in body temperature, a slowing of the metabolism, a reduced heart
rate and slowed breathing.
“When
a true hibernator goes down, they shut their body down for the season,” August
said. “It isn’t remotely connected to being asleep.”
Successful
hibernation requires lengthy preparation. Animals begin by putting on excess fat
to provide them with enough energy to sustain them through the winter months.
I
typically achieve this by hoarding sweets and leftovers following Thanksgiving
and Christmas dinner. But most hibernating animals pack on the calories
throughout the fall before entering their winter dens. Some smaller animals
like chipmunks, which enter a reduced hibernation state called torpor that they
awaken from periodically during the winter, cache large quantities of food in
their burrows during autumn so they can nibble on it when they awaken.
While
taking a three or four month nap may sound appealing, hibernation is not
without its risks. If an animal hasn’t put on enough fat to last the winter,
they may wake up too soon, which raises their metabolism and body temperature
and speeds up the depletion of their fat reserves before additional food
becomes available. It usually has tragic results.
That’s
similar to what has caused millions of bats to die around the eastern U.S. in
the last decade. An invasive fungus in the caves where they hibernate causes
white nose syndrome, a disease that arouses the bats from their hibernation too
soon. With no insects to prey upon in the middle of winter, the bats quickly
use up their energy reserves and die of starvation.
Although
true hibernation only occurs in mammals, other local creatures exhibit somewhat
similar behaviors to survive the winter cold. Wood frogs, for instance, hide in
the leaf litter and nearly freeze solid without any negative physiological
effects. Painted turtles burrow into the mud at the bottom of a pond, surviving
for long periods without oxygen. And garter snakes gather in massive
aggregations – sometimes numbering in the thousands – in underground burrows,
where they remain alert but quite sluggish.
Whatever
your chosen strategy for outlasting the winter, be happy that at least you get
to spend most of it indoors. With the exception of a few mice in my house, Rhode
Island’s wildlife doesn’t have that option.
This article first appeared in the Independent on January 19, 2017
No comments:
Post a Comment