Most reptiles and amphibians remain in the same area most of their lives. During the winter they have various techniques to help them survive the colder temperatures, both above water and under it.
Many turtles burrow into the ground, either on dry land or in the dense mud at the bottom of lakes, streams, and other bodies of water. The Eastern Box Turtle, for example, burrows under fallen leaves or in hollowed out tree stumps to wait out the winter. Picking a safe spot to hunker down is essential to the turtle’s survival.
Many terrestrial frogs, such as American Toads, also burrow into the soil for safety and warmth. If they can dig deep enough, they can get safely below the frost line. Some frogs, who are not adept at digging, will instead seek out deep cracks and crevices in logs or rocks, or simply dig down as far as they can in the leaf litter. These nesting places are not nearly as well protected and may freeze, along with their inhabitants. Freezing, however, does not signal the end for a frog. Frogs have a high concentration of glucose in their vital organs that prevents freezing. Partially frozen, a frog will appear dead–it’s heart will stop beating and lungs will no longer draw breath–but when temperatures rise above freezing, the frozen portions of the frog will thaw and its heart and lungs will “come alive!”
Aquatic turtles face different a different set of issues than their land dwelling counterparts. For them, lack of oxygen is more of an issue than lack of food, cold, or the availability of safe and protected spaces. Their winter hibernation is essentially one long dive (Winter dives can extend over six months!). After the surface of the water ices over, their is no opportunity for animals to breach the surface. As winter progresses, snowfall covers the icy surface and prevents light from reaching aquatic plants. This further diminishes the availability of oxygen. A turtle’s survival depends on its ability to find, accumulate, and store oxygen in its tissue.
Aquatic frogs also winter underwater but, unlike turtles, they do not burrow under mud. Turtles can slow their metabolism down so drastically that the muds meager oxygen supply can sustain them. Hibernating aquatic frogs, however, require more oxygen and must be near oxygen-rich water. They spend much of the winter partially buried or lying on top of the mud.
Interested in learning more about animals in the winter? Be sure to pick up or download a copy of Winter World: The Ingenuity of Animal Survival by Bernd Heinrich.