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Butler's garter snake

Thamnophis butleri

What do they look like?

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.

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Range length
    38.0 to 73.7 cm
    14.96 to 29.02 in

Where do they live?

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.

What kind of habitat do they need?

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.

How do they grow?

Butler's garter snakes are ovoviviparous. Eggs are fertilized within the female's body and develop and hatch within her.

How do they reproduce?

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.

  • How often does reproduction occur?
    Butler's garter snakes breed once each year.
  • Breeding season
    Butler's garter snakes breed in the spring (March to April) and have their young in late summer.
  • Range number of offspring
    4.0 to 20.0
  • Average number of offspring
  • Average age at sexual or reproductive maturity (female)
    2-3 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    730 days
  • Average age at sexual or reproductive maturity (male)
    2-3 years

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.

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female

How long do they live?

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.

How do they behave?

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.

  • Range territory size
    30 to 270 m^2

How do they communicate with each other?

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.

What do they eat?

Butler's garter snakes eat mostly earthworms. They will also eat leeches, small frogs, and salamanders.

  • Primary Diet
  • carnivore
    • eats non-insect arthropods

What eats them and how do they avoid being eaten?

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.

What roles do they have in the ecosystem?

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.

How do they interact with us?

Butler's Garter Snakes help to control garden pests such as slugs.

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

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.

University of Michigan Museum of ZoologyNational Science Foundation

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Dewey, T. . "Thamnophis butleri" (On-line), Animal Diversity Web. Accessed April 17, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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