Curiosities: How do frogs, toads and other amphibians survive the Wisconsin winter?

Amphibians are at great risk during the winter but employ several strategies for getting through, says Scott Craven, professor of forest and wildlife ecology at the University of Wisconsin–Madison.

Some species, like leopard frogs, overwinter below the ice on the bottom of streams, ponds and marshes. Others, like tiger salamanders, burrow into the forest floor and try to stay below the freeze line.

Peepers and wood frogs may freeze solid in shallow upland soil, but as they cool down near the freezing point, their metabolism accelerates and they produce a glycol-like “antifreeze” that protects their cells. Although the cells do not freeze, the body fluid does, and all systems shut down until the spring thaw. 

Since wood frogs winter near the surface, they are among the first frogs to come back to life and are thus the earliest singers, Craven says.

“A really cold, dry winter is bad news for amphibians,” Craven adds, “because some species can essentially freeze-dry and die. But even then, some aquatic species, like newts and mudpuppies, go on with business as usual all winter.”