Curious Nature: Snake hibernacula is the key to a cold-blooded winter
Ever wonder why you’ve never seen a snake slithering through the snow? That’s because snakes spend their winters underground, coiled up by the hundreds, sometimes thousands.
Snakes, like all other reptiles, are cold-blooded. This means that they rely on heat from their outside environment to keep warm. Snakes have special strategies that allow them to survive the winter months without freezing. These strategies are put to the ultimate test during long cold winters here in Eagle County.
Starting in September, snakes will search out a winter den, called a hibernaculum. These cozy winter hideaways are usually natural cavities in the earth made from abandoned animal burrows, or fissures in the bedrock.
Snakes have also been known to take advantage of human-built structures such as building foundations or wells. A good hibernaculum is located below frost line, in a relatively humid place to help prevent snakes from drying out. Snakes of different species will travel long distances to coil up in a hibernaculum by the hundreds or thousands in order to help conserve heat. I can’t even imagine stumbling upon that kind of group.
Once everyone is cozy underground, snakes will slow their heart rate, respiratory system and metabolism; entering a state similar to hibernation called brumation. During brumation snakes are lethargic and do not eat. They are able to avoid starvation because they do not expend much energy.
Even if there was something to eat in the hibernaculum, snakes would not be able to digest it while in brumation because their digestive system is essentially shut off. Time in the hibernaculum can fluctuate depending on the intensity of the winter, but snakes typically tend to emerge in late springtime after the snow melts.
Around 30 different species of snakes live in Colorado, but only a few are found here in Eagle County because our winters are so long. Most snakes are not able to incubate their eggs for long enough during our short summers. This means that their young aren’t given the opportunity to grow large enough to survive the next winter.
The most common snake in the county is the western terrestrial garter snake. These snakes give birth to live young instead of laying eggs. This is their unique advantage that allows them to thrive in our county. They are characterized by a greenish gray base color, and two yellowish white stripes that run down the length of their body.
Western terrestrial garter snakes are found in a wide range of habitats up to 11,000 feet. They have a mild neurotoxic venom in their saliva that helps them kill a variety of prey such as fish, toads, small mammals and insects. Don’t worry, this mild venom is not dangerous to humans and the presence of garter snakes is actually great for your garden as they keep pest populations in control.
An increase in human development has taken away many viable snake hibernacula, limiting snake populations. What can you do to help our local snakes out? A huge way to help is to simply be tolerant of their presence. You could also consider building a snake hibernaculum in your yard. This will help give snakes a chance for winter survival that have been impacted by habitat loss and habitat fragmentation.
Sarah Noyes is a Naturalist at Walking Mountains Science Center. You can find her frolicking through the forest on snowshoes, or quietly sitting on the banks of the Vail beaver pond. Sign up for a snowshoe tour with Sarah at Walking Mountains Science Center or the Nature Discovery Center before the winter’s over.