As the leaves flash brilliant hues and the sun moves into the southern sky, other changes are happening quietly in the fields and on forest floors of Vermont. Reptiles and amphibians are beginning their yearly trek from the summer homes where they’ve fed since spring to the hidden nooks and deep pools where they’ll wait out the dark days of winter. It often involves a dangerous crossing over roadways that lie between their summer and winter homes.
Vermont scientists who study reptiles and amphibians are on the lookout for these migrating creatures and they ask the public to be watchful, too. People can help snakes and turtles this time of year by literally giving them a lift across a busy road, or at least by reporting where they spot the critters bound for winter homes.
Triggered by fall’s cool weather and frost, snakes begin moving away from their summer locales. The largest snakes in this area are northern water snakes, herpetologist and UVM Environment and Natural Resources lecturer Jim Andrews said, and they’re already moving, traveling up to a couple of miles. Smaller snakes, heading out now, may only go a couple hundred yards, but the journey can still be a dangerous one.
Andrews also works on the Vermont Reptile and Amphibian Atlas Project, part of Vermont Family Forests, a nonprofit conservation organization in Salisbury, Vt. This is a busy time for researchers who track reptiles and amphibians with an eye toward conservation.
In their travels, snakes venture onto roads to reach their winter destinations or just to take a break on pavement warmed by the sun. To a snake, a road may resemble a rock ledge, a nice basking spot, Andrews said.
“Sadly,” he added, roads are “a very unsafe place to do that.” Near Shelburne Pond is one location where traveling snakes are often hit by cars, Andrews noted.
Snakes spend the summer feeding, helping to keep other animals’ populations in check, Andrews noted. Their diets vary, from round snakes’ preference for slugs and snails to timber rattlesnakes that, true to their name, eat small mammals in the woods. But “they’re not feeding at all in the winter – they’re just in cold storage,” Andrews said.
Vermont’s largest snakes, timber rattlesnakes and Eastern rat snakes, are already headed for the south-facing slopes where they overwinter. Such sites allow the snakes to “extend their year a couple weeks on each end by being in a good sunny location,” Andrews noted.
Timber rattlesnakes den in groups, returning from a couple of miles around to the same locations each year – found, Andrews said, using scent. Special pockets in the snakes’ mouths allow them to concentrate smells gathered by flicking out their tongues. These snakes don’t live in the Shelburne area, occupying only small pockets of Vermont.
Since snakes are not able to withstand freezing, the ideal location for a winter den, Andrews said, is an upland location, where a snake can be far enough underground to remain below the frost line. Snakes don’t dig, but existing holes serve the purpose. Tiny red-bellied snakes cozy into anthills; “it’s warm and aerated a good place to spend the winter,” Andrews said. Cracks in rocky hillsides work, too.
Though Vermont doesn’t lack stone ledges, snakes are facing another challenge. Global warming is changing weather patterns that snakes have evolved to handle, Andrews noted. Deep snow acts as an insulating layer on top of frozen ground, ensuring that deep freezes don’t reach snakes down in their winter homes. But freezing rain, or cold, snowless days allow a deeper ground freeze, and many snakes won’t survive such winters, Andrews explained.
As any skier knows, hiding is not the only way to survive a Vermont winter, and turtles don’t burrow into the ground to escape the cold. Turtles don’t take up winter sports, though; they head to the bottom of ponds, lakes, streams, and Lake Champlain. As their metabolism drops in the cold water, turtles get the minimal oxygen they need through their skin or linings of their mouths.
Like snakes, turtles face environmental challenges. Nutrient runoff means plenty of summer aquatic plant growth, and these plants then spend the winter decomposing in the water – and using up dissolved oxygen, Andrews said. When this happens, turtles must move during the winter to other areas, usually a stream or spring with running water, to get into a more oxygenated location, he said.
There is plenty that humans can do to help their reptilian neighbors, Andrews said. Reporting sightings to Vermont Herpatlas (vtherpatlas.org) helps researchers track reptiles’ and amphibians’ locations, providing vital information for conservation efforts.
Andrews noted ribbon snakes used to appear around Shelburne Pond, but have not been recently spotted, and might already be extinct from the area. Andrews described the colorful striped snake with “white head and white upper lips.” He said researchers would love to have a record of this snake from Shelburne Pond once more.
Andrews also suggested that – being careful and mindful of traffic – folks comfortable doing so can help move reptiles off the road. Just don’t pick up any snake with a rattle, he added.