Garter Snakes

Local Streams

A Beneficial Local Visitor: The Garter Snake

The common garter snake (Thamnophis species) is one of our most beneficial backyard visitors. Garter snakes are non-venomous and cause no harm to humans. Garter snakes are found in a wide variety of habitats, from coastal and mountain forests to shrub steppe deserts. They are usually found close to water, meadows, wetlands or other wet areas (such as your garden). Garter Snakes are common in urban areas where there is adequate cover, such as large rocks, logs and debris in which to hide. All snakes are very important to the food chain and eat a variety of prey, many of which we consider to be “pests”. Prey species include rodents (mice and voles), snails and slugs, insects, fish and amphibians.

Garter snakes have a highly variable color pattern. The underside is a pale, grayish- blue. Colored red, orange, yellow, green or blue stripes run along the top length of the body. Males are generally smaller than females, up to 2 or 3 feet, and have longer tails. When disturbed, garter snakes will try to escape, but, if threatened, they secrete a foulsmelling substance.

Snakes are ectotherms, or coldblooded animals, regulating their body temperature from external sources such as basking in the sun. Garter snakes are active mainly during the day. They hibernate from late October through March and can sometimes been seen basking on rocks during mild winter days. Common garter snakes hibernate in natural cavities or burrows, such as rodent burrows, under rock piles or in stumps over winter. They are mainly solitary, but they can congregate, lying together forming tight coils to prevent heat loss during the night and when they hibernate over the winter.

When the snakes emerge from hibernation in the spring, they begin to mate. Males attract females by releasing pheromones. After the female has mated, she will return to her summer habitat to feed and to find a suitable birth place. Garter snakes are ovoviviparous, meaning they bear live young. Upon birth, the young are independent and must find their own food.

If you are interested in incorporating habitat spaces in your garden for garter snakes, follow these tips courtesy of the Washington Department of Fish and Wildlife:

  • Protect hibernation sites and other areas used by snakes.
  • Mow at slow speeds and be ready to step on the clutch or brake. Leave grass unmowed in places that adjoin a wet area, sunny forest edge, or any other known snake habitat. If the grass has to be cut, survey the area and move any snakes to a safe location prior to mowing. Set the mower blades as high as possible, or use a weed-whacker and leave grass six inches high.
  • Build a small, fish-free (fish eat all stages of amphibians) pond for amphibians. Many snakes, and garter snakes in particular, feed on tadpoles, adult frogs and invertebrates found in and around ponds.
    Garter Snake Figures
  • Build a rock wall or a rock pile with crevices for snakes to escape from severe weather and predators, to find food and to give birth (Fig. 7)
  • Create a “snake board” by laying a sheet of plywood or corrugated sheet metal on the ground in a sunny location, propping it up on three sides with 3-inch rocks, lengths of plastic pipe, or similar objects. (Fig 8) In cool areas, paint the top black or cover it with dark asphalt shingles to increase the temperature below the board.
  • Place habitat-enhancement features, such as snake boards and rock piles, away from driveways or heavily traveled roads to avoid vehicle/reptile interactions.
  • Discourage cats and dogs from hunting in your yard. If allowed, they are effective hunters and can severely impact snake populations.
  • Encourage your friends and neighbors to preserve wildlife habitat on their property, especially property that adjoins yours.
  • Support public acquisition of greenbelts, remnant forests and other wild areas in your community.
  • Join a local conservation organization or a habitat enhancement project.