Hibernation Tactics at North Pond

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by Carissa Hudson

Animals around the North Pond Nature Sanctuary have their own way of surviving the cold temperatures. Whether it is fleeing entirely or hunkering down like us, each animal has evolved a unique response to the cold.

Common small mammals like chipmunks, squirrels, and rabbits do not necessarily hibernate. They sleep in burrows or large nests and regularly wake to forage for food and to keep up their body temperature. Keep an eye out for their tracks in the snow.

Similarly, the turtles also stick around for winter. They survive just under the ice, where the water stays a consistent temperature without completely freezing. Painted turtles slow their metabolism and absorb oxygen in the water through their hindquarters. Other species commonly found around the Pond–like the snapping turtle–slow down to almost a complete stop, waiting for the water to warm up in the spring.

Frogs have many different tactics for surviving the winter. Terrestrial frogs, like the American Bullfrog, burrow deep into the soil, just below the frost line. Here, the soil remains warm and prevents ice from forming on the frog’s skin. Aquatic frogs will survive just under the ice, moving occasionally to keep their body warm and absorbing oxygen through their skin.

Other terrestrial frogs who are not good at digging, like the spring peeper, will find cracks, crevices, or leaves to hide in. They will completely freeze and sometimes their hearts will also stop. To prevent deadly ice crystals from forming, the frog’s liver will convert glycerol into glucose, a sort of sugar antifreeze. This antifreeze will stop ice crystals from damaging any organs while the frog hibernates. In the spring, these frogs will simply thaw out.

Many of the birds, dragonflies, and butterflies of North Pond migrate for the winter. We await their triumphant return in the spring. Until then, we enjoy the birds that do stick around for winter such as the cardinal, golden finch, and chickadee. They survive the winter by eating native plant seeds. Bird feeders also help these species last all winter. Canadian geese, seen at the Pond year-round, are typically migratory birds; however, geese tend to lose their instinct to migrate around well-populated areas like Lincoln Park. The open water at North Pond and consistent food provided by park goers help the geese stay all winter. There is no push for them to migrate.

Our restoration efforts help keep the habitat around North Pond healthy for these resident animals (and will add more native plants near the shoreline to deter more geese). Native prairie gardens provide food, shelter, and nesting materials that help make winter a little easier for these critters. Learn more about our North Pond restoration plan and how we plan to enhance this important place for all:

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