SNAKES MIGRATE FOR THE HEAT

Snakes migrate because they are unable to generate their own heat. Their bodies, just like mammals and birds, need to be warm to work well, but unlike mammals and birds, snakes, lizards and alligators must absorb their heat from the outside.

If a reptile is cold, it is inactive.

In the winter, a snake's metabolism comes close to zero, said Raymond Smith, Shawnee National Forest wildlife biologist and botanist. "They have very slow breathing, very slow use of stored fat. They stay that way until sometime next spring. When the temperature starts warming up, they'll start moving out of their dens."

Being cold blooded means snakes are susceptible to extreme climatic changes. A particularly cold winter can decimate a reptile population. Hot summers don't necessarily mean happy snakes either. Reptiles have to be cautious during the summer that they do not become overheated.

There are fewer types of snakes in the northern regions than in the South. The snakes that have been able to adjust to the longer periods of migration, and adapted to the cold, are the ones that can live in the North.

All snakes in the colder regions, including the Midwest, hibernate, but not all of them migrate. Because the immediate area, from Lake Kincaid in Illinois to south of Jonesboro has a proliferation of exposed limestone and sink holes, the snakes of this region migrate.

"Anywhere you have exposed limestone or some other type of habitat that they can hibernate in, the snakes will use that," Smith said. "Then in the summer they will spread out from that."

If a snake does not have the luxury of a limestone bluff, it will hibernate wherever it can.