Thamnophis butleri

Geographic Range

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. Throughout its range, Butler's garter snakes are often found in isolated populations as their preferred habitats are increasingly fragmented by human habitat destruction.

• Biogeographic Regions
• nearctic nearctic

Habitat

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 .

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• scrub forest scrub forest

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Wetlands
• marsh marsh
• swamp swamp

• Other Habitat Features
• urban urban
• suburban suburban
• agricultural agricultural
• riparian riparian

Physical Description

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. There are 19 scale rows total and the anal plate is single.

Male 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.

• Other Physical Features
• heterothermic heterothermic

• Sexual Dimorphism
• female larger
• sexes shaped differently

Reproduction

Butler's garter snakes breed each year as they emerge from winter hibernation sites. Rising air temperatures prompt males to begin courting females. Female Butler's garter snakes are capable of storing sperm from previous matings (perhaps occurring in the fall) and using that sperm in the spring.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

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

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• ovoviviparous ovoviviparous
• sperm-storing sperm-storing

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

Lifespan/Longevity

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

Behavior

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.

• Key Behaviors
• terricolous
• natatorial natatorial
• diurnal diurnal
• nocturnal nocturnal
• crepuscular crepuscular
• sedentary sedentary
• hibernation hibernation
• solitary solitary

Communication and Perception

All snakes have evolved special ways in which they perceive their environments. Their senses of taste and smell are combined by the use of a special organ, called the Jacobson's organ. This organ is composed of two specialized sensory pits located on the roof of the snakes' mouth. By flicking their tongues in and out rapidly, the snake transfers molecules from the air, as well as from things it may actually touch with its tongue, to the Jacobson's organ. This specialized sense is the way snakes gather and analyze most of the information from their environment.

Snakes are also highly tactile and sensitive to vibrations. Snakes have only an inner ear and they can probably detect low-frequency sounds.

Compared to other snakes, garter snakes have relatively good vision. However, vision is not the primary way that they perceive their environment.

Garter snakes primarily communicate with each other through pheromones, which act to stimulate reproduction. Touch may play a role as well.

• Communication Channels
• tactile tactile
• chemical chemical

• Other Communication Modes
• pheromones pheromones
• scent marks scent marks

• Perception Channels
• visual visual
• infrared/heat infrared/heat
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

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

• Primary Diet
• carnivore carnivore
  • vermivore

• Animal Foods
• amphibians
• fish
• mollusks
• terrestrial worms

Predation

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.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

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. They are parasitized by certain species of trematodes.

Economic Importance for Humans: Positive

Butler's garter snakes occupy an important ecological niche within their geographic range. They help control the population of earthworms, leeches, and slugs which often makes them a friend to gardeners.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse affects of Butler's garter snakes on humans.

Conservation Status

Butler's garter snakes are much less common than their larger relatives, common garter snakes . They are easily disturbed 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.

Other Comments

Butler's garter snakes were named after early Indiana naturalist Amos Butler. The scientific name comes from Greek 'thamn', meaning shrub or bush, and 'ophis,' meaning snake.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (author), Animal Diversity Web.

Jennifer Loup (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

References

Behler, J., F. King. 2000. National Audubon Society: Field Guide to Reptiles and Amphibians . New York: Alfred A. Knopf Inc..

Brattstrom, B. 1965. Body Temperatures of Reptiles. American Midland Naturalist , 73/2: 376-422.

Carpenter, C, 1951. Comparative Ecology of the Common Garter Snake (Thamnophis s. sirtalis), the Ribbon Snake (Thamnophis s. sauritus), and Butler's Garter Snake (Thamnophis butleri) in Mixed Populations. Dissertation. .

Carpenter, C, 1953. A Study of Hibernacula and Hibernating Associations of Snakes and Amphibians in Michigan. Ecology , 34/1: 74-80.

Carpenter, C, 1956. Body Temperature of Three Species of Thamnophis. Ecology , 37/4: 732-735.

Conant, R., J. Collins. 1998. Reptiles and Amphibians: Eastern/Central North America . New York: Houghton Mifflin Company.

Environment Canada, 2002. "Species at Risk: Butler's Gartersnake" (On-line). Environment Canada. Accessed March 21, 2002 at http://www.speciesatrisk.gc.ca/species/search/SearchDetail_e.cfm?SpeciesID=588#note .

Gould, F. An Introduction to the Natural History of North American Garter Snakes with Basic Triage Practices.. Journal of Wildlife Rehabilitation , Vol. 21 (3-4). Accessed 03/15/02 at http://www.thamnophis.com .

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region . Ann Arbor, Michigan: The University of Michigan Press.

Holman, J., J. Harding, M. Hensley, G. Dudderar. 1999. Michigan Snakes . East Lansing, MI: Michigan State University Extension/MSU Museum.

Jayne, B, , Bennet, A. 1990. Selection of Locomotor Performance Capacity in a Natural Population of Garter Snakes. Evolution , 44/5: 1204-1229.

Shine, Richard, 1991. Intersexual Dietary Divergence and the Evolution of Sexual Dimorphism in Snakes. American Naturalist , 138/1: 103-122.

Toronto Zoo. 2002. "Adopt-A-Pond" (On-line ). Toronto Zoo. Accessed 03/21/02 at www.torontozoo.com/adoptapond/guide/butlergartersnake.html .

The Center for Reptile Conservation and Management. "Butler's Garter Snake: Thamnophis butleri" (On-line ). Indiana University Purdue University Fort Wayne. Accessed 03/21/02 at herpcenter.ipfw.edu/outreach/accounts/reptiles/snakes/Butlers_Garter_Snake.htm .

American Psychological Association. 1989. Stimulus Control of Antipredator Behavior in Newborn and Juvenile Garter Snakes. Journal of Comparative Psychology , 103/3: 233-242.