Across the vast continent of North America temperatures have plummeted. As I write this, sub-zero winds sweep across the Great Plains. Buffalo is seemingly gone–buried beneath uncounted tons of lake-effect snow. Obviously, with all of this November cold, Americans are obsessed with one question: what happens to snakes in the winter?
Snakes live in places that get very cold during the winter, yet the poor reptiles are cold-blooded and can’t be slithering around in snow and ice. In fact, considering that their bodies become the same temperature as their surroundings, how do they avoid becoming snakecicles? What happens to them when the mercury dips?
Technically speaking, snakes (and other reptiles & amphibians who live in climes which turn cold) do not hibernate—they brumate. Brumation is a different sort of metabolic dormancy than mammalian hibernation, but there are many similarities. When reptiles go dormant, their breathing and heart rate drop to almost nil. Brumating reptiles do not eat (or produce waste)—though they wake up occasionally from their dormancy to drink water.
As temperatures dip in autumn, temperate reptiles get all Roman and they seek out a hibernaculum—a sheltered environment which protects them throughout the winter. Hibernaculums are usually deep within the ground in holes, crevices, and burrows which reach beneath the frost line. Certain species of snakes brumate together to share trace warmth. Just imagine a colony of hundreds of little garter snakes in suspended animation beneath a snow covered rock wall in that picturesque New England snowscape!
Although it is not exactly the topic of this post, amphibians and aquatic reptiles also brumate—sometimes underwater or deep within the wet mud at the very bottom of ponds and lakes! The turtles, frogs, and newts take in sufficient oxygen through their skin to stay alive in their deeply reduced metabolic state—although they occasionally wake up from their torpor and swim about. An indelible memory of my childhood is seeing some little newt swimming beneath the ice of the frozen cranberry bog which I was standing on!
When spring comes and temperatures become warm enough, the snakes depart from their underground dens and sun themselves until they have sufficient energy to become active. Of course some reptiles live in such wintry locations that they have very little summer. There are snakes (like northern rattlesnakes) which brumate 8 months out of the year! Scientists believe that this prolonged dormancy allows the snakes to live longer—like an automobile turned off in a safe garage.