Nature Note: The Wood Frog
By Joe Settles

We are now fully into winter. There is snow on the ground, and you hear the sound of squabbling ducks. You investigate. You creep to the edge of the pond and nothing is there. No ducks, no geese, no birds, no nothing.

The cool thing is that there is something there – Wood frogs (Rana sylvatica). That’s right – frogs calling in January – how cool is that! Wood frogs like it cold – real cold. They are the only species of frog known in Alaska! They can actually freeze (to a point), thaw out, and then take off hopping.

They actually increase the amount of glucose or sugar in their cell fluids, which lowers the freezing point allowing them to live in cold weather. About 1/3 of the wood frog’s body fluid can become frozen without causing harm to the frog.

It is an explosive breeder. Breeding for the entire year in a population may take place in a day or two. The frogs begin heading to the ponds during warm winter rains. Usually in mid-late January wood frogs will begin calling on those warm and sunny 45 days.

The call of the wood frog sounds like squabbling ducks (you’ve got to hear it to believe it). The females are attracted to the boy with the best voice (Elvis in the frog world) and breeding takes place.

Females will deposit 1000-3000 eggs in one mass, and collectively the pond may contain 100,000 wood frog eggs. Hatching takes place one to three weeks later, and the tadpoles transform into baby froglets in a few more weeks.

This species can be identified by its bronze body color and a brownish/blackish patch behind the eyes. It is not a large frog. Normally this species is about 2” long (record size 3 ¼”), and the females are usually larger than the males.

In Kentucky, the wood frog is found in (you guessed it) wooded areas. The species is common in the Cumberland Plateau and scattered populations occur in the Knobs Region. It is rare in the Western Kentucky Coalfields, and it is completely absent from the Bluegrass and Jackson Purchase Regions.

Keep your ear out for this frog calling in woodland ponds from January into March. With any luck you may find them close to home. Enjoy!

Joe Settles is a biologist with Kentucky’s Touchstone Energy Cooperatives