News & Events

Wood Frogs

(by Jane Kolias)

Wood Frogs (Lithobates sylvaticus) are one of the first frogs to emerge in spring from winter hibernation. They gather in vernal pools (seasonal depressional wetlands), to breed and lay eggs. Males arrive first, gathering in groups called leks, and call to attract females. Their call has been described as sounding like ducks quacking or chickens cackling.

Wood frogs spend the winter hibernating underneath leaf litter. They have a unique strategy for surviving the long cold NH winters: they freeze solid! For most frogs this would mean certain death but wood frogs have a unique strategy for coping with freezing. Although ice crystals form between their layers of skin and muscle, the wood frogs’ liver produces large amounts of glucose that prevents ice formation inside their cells. They spend the winter in a state of suspended animation with no muscle movement or heartbeat. With the return of relatively warmer spring temperatures, wood frogs begin to thaw from the inside out. The heart starts beating, brain function increases and other muscles become active.

Learn more about Wood Frogs at Wood Frogs in NH.

Watch (and hear!) Dyanna and Becky’s Wood Frog/vernal pool adventure.

Photo: National Park Service