Winter in the mountains is marked by abundant snowfall. As mountain residents we are hard wired for winter preparation. When the trees have shed most of their leaves and become an array of barren branches, we like the squirrels are diligently preparing for a long, cold winter. Barbeque grills and lawn furniture get tucked away, wood piles are stacked wide and tall, fuel tanks filled, snow blowers fueled up and snow shovels are conveniently propped near the entrance of homes.
We are prepared and equipped for nature’s cold, white glitter we call snow. With the average daily winter temperature being approximately sixteen degrees, double stuffed jackets, insulated boots and hat & mittens become the general attire. We have our own form of hibernation as we load our cupboards with yummy snacks and settle in for a Netflix marathon.
A freeze/thaw cycle
But hibernation takes on new meaning for the creatures with whom we share the frozen land. From insect to mammal, miraculous adaptations are taking place around us as the cold season sets in. Have you ever taken a walk in fall and seen a Woolly Bear? This cuddly looking orange and black caterpillar is seeking shelter in leaf litter and under logs, this is the place where they will hibernate for the winter. As the temperature drops, the woolly bear dehydrates itself and nearly freezes solid during their frigid slumber.
These winter-faring insects produce a chemical called cryoprotectant that acts as an antifreeze and its purpose is to protect the body tissue and organs from being damaged from freezing. When spring arrives and the temperature rises above forty degrees, this fuzzy caterpillar thaws out and continues their life cycle. Shortly after this thawing process the Woolly Bear will spin a cocoon and emerge a month later as a moth.
Throughout the forest, the wood frog has conquered the cold by settling into leaf litter and freezing during the coldest months. Throughout the winter months they will undergo a series of freezing and thawing depending on the temperature. While frozen, two thirds of the water in their body turns to ice. Their heart stops beating, their blood no longer flows and glucose levels sky rocket. These palm sized creatures are able to withstand temperatures as low as zero degrees Fahrenheit for as long as seven months. When the temperature rises and stabilizes, they unthaw and greet the world with an orchestra of chirps before hopping away.
In the skies another adaptation is taking place. Most birds flee cold weather by migrating south to a warmer climate, but these journeys are dangerous and energy-intensive. The chickadee instead stays here in the mountains. The chickadee has a number of adaptations that help it survive. These little birds store food throughout the fall and are omnivorous, able to take advantage of almost any source of nutrition: insects, arthropods, seeds, berries, and even fat and meat from carrion.
The chickadee stays warm all day by exercising and shivering, but when night falls, it must find shelter. They will seek enclosed tree cavities and at times, any spot that blocks the wind. When the temperature drops very low, the chickadee slips into a state of controlled hypothermia called torpor in which its body temperature falls by about twenty degrees and their heartbeat lowers from 2,000 beats per minute to 500 to conserve energy and lower its metabolism. As the sun rises the chickadee emerge from torpor, warming itself to normal body temperature by shivering and rejoins its mates for another day of life on the edge.
Let’s go to the ponds and see what else has found a way to overcome the cold, harsh temperatures. As ponds drastically change from summer to winter, the painted turtle is going through drastic changes. When ice covers the surface of the water, these reptiles burry themselves in mud, lower their body temperature and metabolism by 95%. Still in need of oxygen, they utilize a spectacular adaptation called cloacal respiration. The blood vessels around the cloaca or rectum are able to extract oxygen directly from water. When spring arrives, they rush to the surface to bask in the sun, adamant in their quest to raise their body temperatures, ignite their metabolism and eliminate acidic chemicals produced during their form of hibernation.
These creatures are just a few among many, adapting to the mountains as they change from lush, green fields to a white-grey, cold hardened landscape. Humans are not alone as we brave the elements. The creatures around us are prepared in their own magnificent way to survive the freeze.