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Reptiles of Washington

Red-spotted garter snake
 (Thamnophis sirtalis concinnus)


What they look like

  • Most red-spotted garter snakes are around 18 inches long.
  • Their body is black with a very visible white stripe along its length.
  • The head is red and, as their name suggests, red-spotted garter snakes have red spots on the sides on their body.

Where they live

  • Can be found in southwestern Washington, northwestern Oregon, and coastal California.
  • They live in habitats close to water, including marshes, wet meadows, prairie swales, damp woodland, farms, parks, and even irrigation and drainage ditches.

What they eat

  • Earthworms and amphibians are the majority of their diet.
  • Small fish, lizards, snails, slugs, crayfish, small birds, and rodents can also be eaten.


  • Between late July and October, females give live birth to 12 to 40 young.

Cool Biology Facts

  • Common garter snakes (Thamnophis sirtalis) are the second-most commonly encountered snakes in Washington.
  • During breeding season, some males can trick other males away from the dens of emerging females. By pretending to be females and producing fake female chemical signals, a trickster male can lure other males towards him and away from females.  


Ian Poellet via Wikipedia Commons

Distribution Map


Common garter snakes (Thamnophis sirtalis) are considered “least concern” due to their extremely large distribution and large stable populations.