Naturalist Notes

Remember spring? The trees were budding, the ice on the lakes melted, and the frogs started making a lot of noise. We learn a lot about frogs and toads in the spring by watching, hearing, and maybe even holding these slimy hoppers; but what are they doing now, as temperatures and leaves are dropping?

All the frogs and toads we have in Northern Minnesota will hibernate for the winter, but they have different ways to keep themselves alive during the long, cold months. They might get ready for winter by changing their blood chemistry, heading under pond muck, of burrowing underground. Each type of frog or toad has its own strategy.

The Spring Peepers, for example, are starting to store glycerol in their blood and body tissues. This works like antifreeze in a car, so the frog’s cells won’t freeze solid. They can hide in the leaf litter or under a piece of tree bark for the winter, with up to 65% of their bodies frozen. In the spring, they will thaw out and begin peeping again.

Other frogs spend the winter deep in the “warm” waters. A Green Frog may bury itself in the muck at the bottom of a pond to hibernate. A Mink Frog or Leopard Frog might spend the winter in the leaves and debris at the bottom of a lake. During these months, their metabolism slows down and they are able to take in oxygen through their skin.

Some frogs, like the Chorus Frog and the American Toad, spend the winter on land. To avoid freezing in the cold winter temperatures, they bury themselves deep in the leaves and dirt where it is a little warmer.

Fun Fact: Did you know that a herpetologist is a scientist that studies reptiles and amphibians?

Emily Bowman-Graf is a Wolf Ridge naturalist who LOVES frogs and their relations. We've often wondered if her husband Dave, also a naturalist here, used to be a frog . . . ?

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