It’s nearing the end of October, the leaves are falling, and temperatures are dropping. That means many animals are spending a final few days in the sun and getting ready for hibernation. Snakes are no exception, although most people don’t give much thought as to what happens to them in the winter. Because snakes are cold-blooded (ectotherms), their body temperatures change according to environmental conditions. When temperatures drop below freezing, snakes can’t help but freeze, as well.
So what do native Minnesota snakes do to survive the frigid winter weather? Most, including the common gartersnake, the species most frequently sighted in the Arboretum, enter a period of brumation. Brumation is a fancy term for reptile hibernation, but it differs significantly from your traditional mammalian hibernation. Snakes don’t actually sleep during brumation – they remain alert, but are generally inactive. Their cold-bloodedness translates to a low resting metabolism, meaning that they don’t require much food to sustain bodily functions. Consequently, they have no need to fatten up in the fall.
Although different species vary in their ability to survive extreme temperatures, most reptiles cannot survive in environments where temperatures dip below 4̊C. The key to winter survival for snakes is to burrow below the frost line, the depth to which groundwater freezes. Since cracks and crannies in the soil that extend this deep are difficult to come by, masses of snakes tend to hibernate together in suitable locations.
So if you happen to be out in the Arb on a warm day, keep a look-out for snakes heading down into the ground.
-Maddie Reynolds ’14, for the Cole Student Naturalists