How Do Frogs Live in the Winter?

Frogs have many different ways of surviving the winter.

Many of the frog species found around the world live in areas that become extremely cold during the winter, and some of these areas fall below freezing temperatures for long periods of time. Frogs do not migrate like some other animals; they have other methods of surviving the winter.

Signals

Like most animals that cannot live in cold temperatures, frogs rely on cues from the outside environment to know when they should begin preparing for the winter. These cues include drops in temperature and barometric pressure.

Biology

Frogs have two lungs like many animal species. They can either breathe with these two lungs or absorb oxygen through their skin. This is pivotal for surviving over the winter, because it allows the frogs to survive in areas they would not be able to survive in otherwise.

Estivation In Water

Some species of frogs estivate in the winter. Because they are cold-blooded, the outside temperature causes their bodily processes to slow down to the point where they don't need to eat. This is different from hibernation, as animals that hibernate are often warm-blooded and merely fall into a very deep sleep over the winter.

Estivating frogs will rest on top or partially burrow in the soft mud at the bottom of lakes, rivers and ponds while the overhead water freezes on the surface. They can live underwater because they continue to absorb oxygen through their skin, and their metabolism is substantially slowed, according to Nature Bulletin No. 485 of the Forest Preserve District of Cook County, Illinois. The frogs must be exposed to the water to survive, otherwise they will suffocate.

Estivation On Land

Some species of frogs, such as toads, only live on land and don't spend their winter in the water. Instead, they burrow in the ground below the frost line. In the winter the ground only freezes a few feet down, and the frogs burrow under this point so they stay warm enough to survive, but cold enough to estivate.

Freezing

A select few species of frog, such as the spring peeper and wood frog, find a safe place to hide over the winter and then freeze.

Most species of animals cannot freeze safely, because the sharp ice crystals that form in their bodies tear up cells and small blood vessels. These frogs on the other hand, have high concentrations of glucose in their bodies. These sugars act as a natural anti-freeze, keeping the frog's important internal organs from freezing solid. The frogs heart will stop beating and it does not breathe for the duration of the winter, but when spring comes these frogs thaw and return to normal.

References

• Scientific American: How Do Frogs Survive Winter?
• Forest Preserve District of Cook Country: Hibernation of Frogs and Turtles
• Nature North: Frozen Alive

Resources

• Northern Wilds: Frogs and Toads Get Ready for Winter