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Common Garter Snake

(Thamnophis sirtalis) Special Concern


Identification: Pale stripes on sides of body on second and third scale rows above outer edges of belly scales; belly pale and unmarked; red blotches between stripes on back (red may be confined to skin between scales); usually seven upper lip scales (lacking heavy black markings) on each side of head; upper scales keeled, in 19 rows at midbody; anal scale single; tongue red at base; maximum total length about 124 cm (49 inches), but usually much smaller in Colorado. The tail sometimes is incomplete due to breakage.    

Colorado Distribution: Northeastern Colorado along the South Platte River and its tributaries at elevations below 6,000 feet and North Fork Republican River drainage in Yuma County at about 3,5003,600 feet; widely distributed along the eastern base of the Front Range.   

View the distribution of observed Common Garter Snake (Thamnophis sirtalis) on a map

Habitat: Marshes, ponds, and the edges of streams; basically restricted to aquatic, wetland, and riparian habitats along the floodplains of streams; seldom found away from water or at isolated ponds. Active in shallow water and on land adjacent to water.    

Life History: Limited information indicates that females give birth to their young mainly in late July and August. The diet includes frogs, toads, amphibian larvae, fishes, earthworms, and rodents, obtained on land or in the water.

Revised: July 24, 2003