Goodness, gracious, snakes alive!
By Dr. Jim Pease, Emeritus
Extension Wildlife Specialist (ISU - Retired)
"Arrgh! There's a snake in the yard!" This is often the reaction of people who come into contact with these common Midwestern wildlife. Unfortunately, in our hysteria, we often strike out at these creatures--with shovels, hoes, even lawnmowers--with lethal results. Our fears are often the result of a combination of childhood experiences and a great deal of misinformation. Educators find, however, that if we can replace the myths about these animals with facts, the fear is very often replaced with interest. Indeed, truth often is stranger than fiction!.
Snakes are reptiles. As such, they have a backbone, often with over 300 vertebrae. They are "cold-blooded", taking their body temperature from their surroundings and therefore, seeking winter places that remain above freezing. They lay eggs and do not care for their young after birth. Two Midwestern types, garter snakes and rattlesnakes, retain their eggs inside their bodies until they hatch, imitating a type of "live" birth typical of mammals.
The skins of snakes are smooth and dry, feeling much like the leather on your shoes. Most Midwestern snakes see poorly and cannot wink at you: they have no eyelids! Instead their eyes are covered by a clear single scale that is shed and replaced each time they shed their skin. While lizards have external ear openings, snakes have none. Their main sense organ, then, is their tongue. It is constantly flicking out, "tasting" molecules from the air to detect what is around them. Unlike humans, a snake's tongue is not used for swallowing. Rather, snakes have rows of tiny curved teeth and separated jaws to "walk" their prey down their throat.
They move by means of the rhythmic movement, called "peristalsis", of muscles on their bottom side. This movement allows the broad, strong scales on their belly ("scutes") to push against rough surfaces and move forward. Having no legs or feet, they cannot dig holes but can occupy dens made by small mammals like ground squirrels and chipmunks. They are extremely important predators, eating a variety of insects, grubs, worms, amphibians, and especially rodents.
The 28 species of Iowa snakes range from the tiny and uncommon 7-inch western worm snake to the common bullsnake which can be over 5 feet long. Most common are several species of garter snakes, the fox snake and the bullsnake. Timber rattlesnakes are common only in some very localized areas. All other poisonous snakes are either exceedingly rare or absent in most of the upper Midwest.
Keeping your foundation and siding in good repair will keep not only snakes from entering your house uninvited, but also mice and insects. Cleaning up hiding places like boards or piles of junk in the yard will limit available habitat for snakes. On the other hand, providing constructed well pits or other hibernacula below ground is an excellent way to attract these important predators to your property, if you so desire.
Snakes are a fascinating part of the Midwest's wildlife diversity. Watch them respectfully from a distance and you will learn to appreciate their adaptations and their roles in the natural world.
For more information about snakes, contact the Iowa DNR for a copy of The Snakes of Iowa, a publication of the Iowa Wildlife Diversity Program or your state's natural resource agency or Extension wildlife specialist.
Photo Credit: Fox Snake - © Jeff LeClere, www.herpnet.net