Common Garter Snake Thamnophis sirtalis
The common garter snake is a medium sized snake measuring 18-26 inches (45.7-66 cm) in length. Max 48 7/8 inches (124.1 cm; Conant and Collins 1998). The ground color is light brown to black with two alternating rows of black spots. There are three distinctive longitudinal stripes. The dorsal stripe is usually yellow or greenish yellow; the lateral stripes are cream, yellow, or gold and are located on the second and third scale rows. There are only a few dark bars on the labial scales, or they may be unmarked. The scales are keeled and the anal plate is single. The similarly marked plains garter snake has lateral stripes on rows three and four.
The red-sided garter snake, Thamnophis sirtalis parietalis, occurs in North Dakota.
Statewide. This snake is widely yet sparsely distributed in North Dakota, and is typically found near water. This species is clearly less common than the plains garter snake in North Dakota. Help us update their range with reports.
The common garter snake is active March through mid October. Moist situations such as marshes, lakes, and river valleys are favored, but grasslands, forest edge, or suburban backyards are also utilized. Common garter snakes overwinter in underground retreats below the frost line such as burrows or road embankments. Common garter snakes breed after spring emergence and many males may court a single female. The young are born alive in late summer or autumn. There may be 10-70 or more in a litter. Common garter snakes are active hunters of earthworms, amphibians, fish, small mice, and birds eggs are consumed. Prey is swallowed alive without constriction. They are known to scavenge small animals.