A frog's life

Posted at 1:20 PM on August 20, 2012 by Dan Gunderson
Filed under: Environment, Research, Water

While reporting a story about land use and wildlife habitat, I collected some interesting tidbits about a frog's life.

The upper Midwest is a harsh climate for amphibians, so we don't have the variety of species you'll find in warmer climes. But the frogs that are here have evolved some rather interesting survival tactics.

The Leopard frog spends winters hibernating at the bottom of a pool of water. Hopefully they choose wisely, because if the pond or wetland is too shallow and freezes solid, the frog won't survive.

Other frog species spend the winter frozen, then thaw out and hop away in the spring.

Boreal Chorus frog

Boreal chorus.mp2
courtesy USGS
Wood frog

Wood.mp2
courtesy USGS

The Boreal Chorus frog and the Wood frog spend winters out of the water, usually under grasses near a wetland. They transport sugars from their liver to individual cells to create a kind of anti-freeze so the cells don't freeze and burst, which would kill the frog.

So they spend the winter essentially frozen in place with all bodily functions suspended.

Climate change and human intervention are helping a new frog hop into Minnesota and the Dakotas.

American Bullfrog

Courtesy USGS

bull frog.mp2
courtesy USGS
The American Bullfrog is now found only in the far southeast corner of Minnesota. But with a warming climate it's expected to move north. And people sometimes buy the frogs for backyard ponds and unknowingly release a species that could threaten our native frog population and take over wetlands.

I think I'd much prefer falling asleep to the sound of Boreal Chorus frogs.