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Colubrids: Colubridae

Common Garter Snake (thamnophis Sirtalis): Species Accounts



Physical characteristics: The common garter is a somewhat thin snake that may be brown, greenish, or red and may have blackish blotches. Garters usually have three long stripes running from top to bottom: a center stripe that may be almost cream in color and two yellow stripes along the sides of the body. Adults range from about 20 to 28 inches (51 to 71 centimeters) in length, but some can reach more than 4 feet (1.2 meters). Females and males look alike, but females are typically a bit larger than males and have shorter tails. Males' tails make up about 25 percent of the snake's overall length, while female tails make up about 20 percent.




Geographic range: This snake lives in Canada, the United States, and Mexico. Some populations live as far south as Florida and northern Common gartersnakes eat a variety of animals, including insects, frogs, and small fishes, birds, and mammals. (Illustration by Barbara Duperron. Reproduced by permission.) Mexico, while others live as far north as Canada and into the southern part of the Northwest Territories.


Habitat: Garters thrive in many habitats, including marshy spots, fields, and forests, especially near water. They also will enter freshwater areas for short periods of time.


Diet: Active during the day, garters eat a variety of animals, including insects, frogs, and small fishes, birds, and mammals.


Behavior and reproduction: Common garters that live in warm southern climates are active all year long. Those that live in the north hibernate during the coldest months. Hibernating males become active a bit earlier in the spring than the females, and mating occurs almost as soon as the females awaken. Females give birth to about ten to fifteen live young.

Common garter snakes and people: Most people know the garter as the snake seen in a garden. In fact, some people call it a "garden snake," and unfortunately many kill these harmless animals. These snakes may also die from encounters with cats and dogs, cars, and lawn mowers. Garters are common pets.


Conservation status: The IUCN does not consider this snake species to be threatened. The U.S. Fish and Wildlife Service lists one subspecies, called the San Francisco garter snake, as Endangered. The danger for this subspecies comes from loss of its habitat. A subspecies is a small group within a species that typically lives in a particular area and usually has a slightly different look from the rest of the animals in the species. ∎

Additional topics

Animal Life ResourceDinosaurs, Snakes, and Other ReptilesColubrids: Colubridae - Physical Characteristics, Habitat, Diet, Behavior And Reproduction, Colubrids And People, Conservation Status - GEOGRAPHIC RANGE