Winters in Cook County can be brutal and for the wildlife in the Forest Preserves, it takes some work to ensure survival until the spring. While some of the Forest Preserves’ mammals do hibernate through the winter, the 70,000 acres of land is home to an abundance of wildlife, including mammals, herps and fish, which adapt to the snow and low temperatures differently.

Here are some examples of wildlife and their tricks of survival during winter:

Herptile: Spring Peeper (Pseudacris crucifer)

Survival strategy: Hiding and freeze prevention
Details: Spring Peepers rely on existing spaces in logs for shelter. The frogs have evolved to help prevent parts of their bodies from freezing including their liver releasing more glucose.

Herptile: Snapping Turtle (Chelydra serpentina)

Survival strategy: Brumation underwater
Details: Snapping Turtles go into brumation. They brumate in lakes and ponds because water underneath ice is above freezing, often warmer than on land.

Herptile: Common Garter Snake (Thamnophis sirtalis)

Survival strategy: Brumation underground
Details: Garter Snakes go into brumation. They rely on heat from the environment by going underground, using holes that already exist.

Fish: Bluegill (Lepomis macrochirus)

Survival strategy: Fatten up and slow down
Details: They fatten up in fall after recognizing reduction in daylight. By late fall/early winter, they eat less, go into a torpor state and “sit” or slowly swim in deeper areas.

Mammal: Thirteen-Lined Ground Squirrel (Ictidomys tridecemlineatus)

Survival strategy: Hibernation
Details: Thirteen-Lined Ground Squirrels eat large quantities of food during spring/summer to build up stores of brown fat, and they go underground in burrows below the frost line to hibernate.

Mammal: North American Beaver (Castor canadensis)

Survival strategy: Store food and spend time in their lodges
Details: Beavers stash twigs, branches and pieces of sapling trees in the mud underwater. They spend more time inside their lodge to stay warm, rest and mate.