Common Gartersnake

Common garter snake.

 

Quick Facts

Scientific name: Thamnophis sirtalis

Identification

• Medium sized snake up to 34 inches long.
• Nearly black or dark green base color with three bright stripes running the length of the body; underside is pale yellow or bluish-gray.
• Most distinguishing characteristics of this species in our region are the irregular red spots along the sides.

Habitat

• Thought to be common in the past, now in decline for no apparent reason.
• Closely associated with permanent surface water.
• In Yellowstone area, observed only in the Falls River drainage in the Bechler region and three miles south of the south entrance along the Snake River.

Behavior

• Generally active during the day.
• In the Yellowstone area it eats mostly toads, chorus frogs, fish remains, and earthworms; can eat relatively poisonous species. Reliance on amphibian prey may contribute to reports of declines of this species in the greater Yellowstone area.
• Predators include fish, birds, and carnivorous mammals.