(Thamnophis sirtalis)
Early settlers thought that certain snakes resembled the garters which people wore during that period. Garter Snakes owe their common name to this fanciful resemblence.
Species from the genus Thamnophis are commonly called garter snakes. There are the San Francisco Garter, the Red-sided Garter, and the Eastern Garter among others. Some species of garter snakes are listed as threatened or endangered, but the easter garter snake is not among them. Only the Eastern Garter Snake occurs naturally in Illinois, but this species is one of the most common snakes in the state. It is certainly the most commonly found snake in areas occupied by humans. Eastern garter snakes are to be found throughout the state, though of course they are more numerous in the south where the weather is somewhat more moderate.
Every type of habitat in Illinois may be found to contain these snakes, but they seem to prefer grassy areas near other terrain features. The author caught his first eastern garter snake as it lay basking in a mown area near higher grass. They are also often found where fields or grassy areas meet rocky areas. Eastern garter snakes often live very close to human homes, especially those with gardens. This proximity to peoples' yards and gardens has led to many people calling them "garden" or "gardener" snakes, though the original and most generally accepted name is "garter".
Eastern garter snakes are so secretive and difficult to see in grass (owing to their highly cryptic coloration) that a person may live alongside several generations of these snakes without ever being aware of their presence.
It is unfortunate that people usually over-react when they discover one of these harmless snakes in their yard or garden. Left alone, an eastern garter snake will quickly retreat, possibly never to be seen again.
Garter snakes have no venom, nor do they need any. Their diet consists of invertebrates like worms and slugs, frogs, minnows and other small fish, a few insects, and occasionally lizards. Even constriction is unnecessary. None of the eastern garter snake's prey is likely to injure it. Therefore, it simply catches a prey item and swallows it alive.
Garter snakes are diurnal and so are often found basking or watching for a meal during the day.
Eastern garter snakes mate in early- to mid- spring and 10 to 30 young are delivered alive in late spring or early summer. In the southern part of their range, eastern garters will sometimes produce more than one brood in a single season. This is important because this species has a high mortality rate among its young. Also, some females have been known to produce multiple broods from a single mating or to deliver a brood up to two years after mating.
