Frogs That Freeze Solid

Wood frog by Brian Gratwicke on Flickr.

Wood frog. Photo credit: Brian Gratwicke/Flickr Creative Commons.

Different animals use different strategies to survive winter. Some species migrate south, others grow thick coats, and some fatten up or stash food reserves. Many species hibernate or go dormant to get through the cold, lean winter.

Amphibians are hibernators. Some species bury themselves at the bottom of ponds and others burrow into the leaf litter or even underground. Even so, amphibian species are less numerous the further north you go. Most species just can’t tolerate the deep cold and long duration of winters in extreme northern latitudes, even when hibernating.

Wood frogs (Rana sylvatica) are an exception. They are the only North American amphibian species whose range extends into the Arctic Circle. They can do this because they have the ability to survive being frozen solidCheck out this video about these amazing frogs.

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Early Breeders

This ability to survive freezing also allows them to emerge from hibernation before most other frog species–sometimes when there is still snow on the ground. This early emergence allows them to breed early in the year, which gives their tadpoles more time to develop into adult frogs.

This is a big advantage, as wood frogs breed in temporary ponds called vernal pools that fill up with melted snow in late winter, but dry out completely by the end of summer. Tadpoles that don’t complete their metamorphosis before the vernal pools dry up don’t survive, so the longer they have to grow, the more will survive to adulthood.

Attracting Wood Frogs

Wood frogs can be found throughout the Mid-Atlantic, Northeast and Upper Midwest states, as well as Alaska and throughout Canada. They can survive in suburban and even urban areas if the right habitat exists for them. Here are some tips to attract wood frogs (or any amphibian) to your yard.

  • Install a Small Garden Pond. Allow some leaves to accumulate in the bottom of your backyard pond, and make sure it has a shallow area for wildlife to enter and exit. Add plants around the banks and don’t put fish in it. If there are wood frogs in the neighborhood, they may show up in the late winter to lay their eggs.
  • Leave Your Leaves. Wood frogs spend most of their time in the fallen leaves of the forest floor, where they hide from predators and lie in wait for insects, spiders and worms to feed upon. They also hibernate right in the this leaf layer. So if you have woods on your property, preserve them and don’t rake up all your leaves in fall.
  • Don’t Use Chemicals. Chemical pesticides and fertilizers can kill frogs or eliminate their prey.
  • Plant Natives. Frogs don’t eat plants, but they eat the insects and other small animals that do. Native plants support more insects than exotic ornamental plants. A good diversity of native plants in your garden will ensure that there is plenty of food for wood frogs.
  • Give Cover. Plants also provide cover where wood frogs can hide. Consider creating a brush pile too, which mimics the fallen woody debris naturally found on the forest floor.


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