Wisconsin’s Reptiles And Amphibians Prepare For Winter

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• Wisconsin’s Reptiles, Amphibians Are Skilled At Surviving A Harsh Winter

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  Reptiles and amphibians are fascinating creatures, and they play an important role in the ecosystems where they live, including Wisconsin.

  According to Rori Paloski, a conservation biologist with the Wisconsin Department of Natural Resources who specializes in herptiles, there are 19 species of amphibians and 36 species of reptiles that are native to Wisconsin.

  “I think it surprises a lot of people,” she said, “because it’s not a group of species that you see very often.”

  Frogs, though, are at least easier to hear, said Rich Staffen, a zoologist in Natural Heritage Conservation for the state Department of Natural Resources. (Note: There is a quiz of common frog sounds below. Audio of many more species in Wisconsin and in the Eastern U.S. is available via the Wisconsin Frog and Toad Survey and the U.S. Geologic Survey website.)

  One of the amazing aspects of herptiles living in Wisconsin is how cold-blooded creatures like that can survive a long, sometimes rough winter. Paloski said that they have a variety of different strategies. Some snakes will hibernate individually, she said, often in a burrow of a small mammal or even a crayfish.

  On the other hand, garter snakes are known to hibernate communally, Paloski said. Hundreds may spend the winter in the same burrow and they use scent trails to find their way back to the same hibernacula each year. She added that they might congregate anywhere from an old well in an urban area to “really pristine habitats way away from civilization.”

  Frogs also need to find a well-protected and temperate spot to pass the winter. Wisconsin’s only toad species, the American toad, burrows into the ground deep enough to stay below the frost line for the entire winter, according to Paloski.

  Some of the larger frog species, like the bullfrog, leopard frogs, and green frogs need a permanent body of water that is at least three feet deep, Paolski said. They will then spend the winter on the bottom of that lake, partially burrowed into the muck.

  For Paloski, the most interesting technique for surviving a Wisconsin winter is that of the tree frogs. She explained that they have the biological equivalent of an anti-freeze that it glucose-based. It “allows them to freeze partially solid in the winter without their cells breaking down,” she said. As a result, they pass the winter under leaf litter on the forest floor, often covered in snow. Four or five species in Wisconsin are able to do that.

  “Then, they thaw out and go on their way in the spring,” she said.

  Quiz Time!

  To try your hand at identifying some of Wisconsin frogs, listen to the audio below. There are four frog calls that you will hear, with an assigned number. Match the call to the corresponding species listed here:

  • Wood Frog
  • Spring Peeper
  • Northern Leopard Frog
  • American Bullfrog

  At the end of hearing the four calls, you will then hear the calls again with the answer.