Butler's garter snakes are small, stout garter snakes with three well-defined yellow or orange stripes that run along the length of their body on a background color of black, brown, or olive. They sometimes have two rows of dark spots running between their central stripe and the two side stripes. Their head is relatively narrow, not much wider than their body, and their scales are keeled (with a ridge along the length of the scale). Their belly color is pale green or yellow with black spots running along the edges. Adults reach a total length of from 38 to 73.7 cm. Males snakes are slightly smaller than females, and have slightly longer tails. Young Butler's garter snakes are born at from 12.5 to 18.5 cm. Other garter snakes have somewhat longer and larger heads than do Butler's garter snakes. Other sympatric garter snake species can be distinguished from Butler's garter snakes by the position of the lateral (side) stripes relative to the dorsal scale rows. One must count the scale rows from the ventral scales to the dorsal scale row and note on which row of scales the stripes occur. In Butler's garter snakes, the stripe is found on the third scale row, and also runs partially onto the upper part of the second row of scales and the lower part of the fourth scale row. In contrast, eastern garter snakes have stripes confined to scale rows 2 and 3. Often, juveniles are more distinctly marked than adults.
Butler's garter snakes are found in the southern Great Lakes region and into Indiana and Illinois. There are isolated populations in southern Wisconsin and southern Ontario.
Butler's garter snakes prefer wet meadows and prairies. They are often found near marshy ponds and lake borders. These kinds of habitats sometimes occur in suburban and urban areas and relatively large concentrations of Butler's garter snakes can be found in those areas. Specific habitat preferences may help to reduce competition with their close relatives, eastern garter snakes and northern ribbon snakes.
Butler's garter snakes are ovoviviparous. Eggs are fertilized within the female's body and develop and hatch within her.
Butler's garter snakes breed each year as they emerge from winter hibernation sites. Rising air temperatures cause males to begin courting females.
Butler's garter snakes mate at their hibernation sites in the spring, before they leave for their summer feeding areas. Females give birth in mid to late summer to from 4 to 20 live young. Larger females and those that are better nourished produce more young per litter. The young snakes grow rapidly and may become mature in their second or third spring. They continue to grow throughout their lives.
Female Butler's garter snakes nurture their young inside their bodies until they are born. Once the young are born there is no further parental care.
The potential lifespan of Butler's garter snakes is unknown. The highest recorded lifespan in captivity is 14 years, average captive lifespans range from 6 to 10 years. Most wild individuals probably do not live as long as this due to predation and environmental stresses.
Butler's garter snakes are active generally from late March to October or November of each year. They are most often seen in spring and fall and may become nocturnal during the summer months. They retreat to underground hibernation sites during cold weather, often in rodent or crayfish burrows or in natural cavities or under rock piles. These are secretive snakes and they are mainly active underground. Butler's garter snakes are mostly solitary, though they congregate at hibernation sites. They may occupy hibernation sites with eastern garter snakes as well.
Butler's garter snakes, like all snakes, are ectothermic and must maintain their body temperature by choosing different microhabitats for periods of time. They may be seen sunning themselves on rocks or bare ground, especially when they are digesting. They seek shelter in order to cool body temperatures.
These are docile and shy animals. They most readily flee when approached and are not easily provoked to bite.
Butler's garter snakes communicate with each other primarily through touch and smell, especially for breeding. Outside of the breeding season they do not interact much with other snakes. They use their forked tongues to collect chemicals from the air and insert these forks into a special organ in the roof of their mouth, which interprets these chemical signals. Snakes are also sensitive to vibrations and have reasonably good vision.
Butler's garter snakes are preyed upon by most predators throughout their range, including milk snakes, American crows, hawks, owls, raccoons, skunks, weasels, shrews, foxes, and domestic cats. They escape predation by attempting to escape. If harassed, though, they will exude a foul-smelling substance. If they are suddenly surprised they will thrash their bodies violently from side to side, perhaps to confuse predators and startle them in turn.
Butler's Garter Snakes help to control populations of earthworms, leeches, and slugs. They also act as important food sources for their predators where they are abundant.
Butler's Garter Snakes help to control garden pests such as slugs.
Butler's Garter Snakes are much less common than their larger relatives, Common Garter Snakes. They are easily distubed by habitat destruction and other human modifications of their habitats. The wet meadow habitats that they prefer have been largely eliminated and are still being developed at a rapid pace. Large colonies may survive in small pockets of habitat, even in abandoned urban lots, but these colonies can be eliminated in one afternoon when the land is bulldozed. They are listed as endangered in Indiana.
Tanya Dewey (author), Animal Diversity Web, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.