Mildly venomous, harmless to people · Native to western North America

Western terrestrial garter snake

Thamnophis elegans (Baird & Girard, 1853)

Data updated October 2026

Western terrestrial garter snake on dry sandy soil with its tongue out, showing a pale back stripe and dark spots
Fig. 1 — Adult on dry ground. The pale stripe down the back and rows of dark spots are typical.
Head of a western terrestrial garter snake among grass stems
Fig. 2 — Head among grass. The eye is large and the head only a little wider than the neck.

At a glance

A variable, striped garter snake of western North America, found from deserts to mountain meadows. It hunts by day, often near water, and gives birth to live young. Its mildly toxic saliva is not a danger to people.

01

Identification

This is a medium-sized garter snake with an olive, gray or grayish-green body. A yellow or whitish stripe runs down the middle of the back, and a paler stripe runs along each side. Rows of dark spots sit between the stripes, giving a checkered look. The belly is yellowish. Females grow larger than males.

  1. 01Three pale stripes. One down the middle of the back and one low on each side.
  2. 02Dark spotting. Small dark blotches between the stripes, often in a checkered pattern.
  3. 03Olive to gray ground color. Color and pattern vary from place to place across the range.

02

Size

01 ft2 ft3 ft4 ft Typical adult · about 30 in (76 cm)

Adults measure 18 to 41 inches (46–104 cm). Females are usually larger and heavier than males.

03

Range & habitat

Western terrestrial garter snake swimming among grass at the edge of a pond
Fig. 3 — Despite its name, this snake is often found in or near water.

The range runs from southern Canada to northern Mexico and from the Pacific Coast east into the western Great Plains, including the Dakotas and Nebraska. It occurs from sea level to about 13,100 feet (3,993 m).

It uses a wide range of habitats: desert, grassland, mountain meadows, woodland and coniferous forest. Many populations stay close to lakes, ponds and slow streams.

04

Diet & predators

Diet depends on where the snake lives. Coastal populations eat mostly land animals such as slugs, salamanders, lizards and small mammals. Inland populations take more aquatic prey, including tadpoles, frogs, leeches and fish. It also eats insects and small birds. It is the only garter snake known to constrict its prey, though it is a weak constrictor.

Feeds on

  • Frogs and tadpoles
  • Fish and leeches
  • Slugs and insects
  • Small mammals and lizards

Preyed on by

  • Hawks and eagles
  • Herons
  • Raccoons and minks
  • Opossums

05

Behavior & seasons

Western terrestrial garter snakes are active by day. They bask in the morning, then hunt. Most of the year they live alone, but in winter many gather to hibernate together in deep burrows or rock piles.

In mountain areas such as Bryce Canyon they are seen only in spring, summer and fall. Their saliva is mildly toxic to small prey and can cause a minor allergy-like reaction in people, but it is not dangerous.

06

Reproduction

Mating takes place mainly in spring, soon after the snakes leave their winter dens. The young develop inside the mother for two to three months and are born live, mostly in August and early September. A litter usually holds 8 to 12 young, with 4 to 19 recorded.

07

Conservation

The species is listed as Least Concern. It is widespread, its total population is large, and it faces no major range-wide threats.

Keep reading

Sources

Data updated October 2026 · How we build these pages