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Canadian Amphibian and Reptile Conservation Network - Réseau Canadien de 
Conservation des Amphibiens et des Reptiles

Thamnophis ordinoides
Northwestern Gartersnake
Couleuvre du Nord-Ouest


Northwestern Gartersnake

The Gartersnakes, and other live-bearing, harmless snakes, which were included within the Family Colubridae, have recently been placed in the Family Natricidae.

Description
The Northwestern Gartersnake varies in colour from brown, greenish, bluish or black, but it usually has a distinct red, orange or yellow stripe down the middle of the back. The belly is yellow or gray, often with red blotches. The Northwestern Gartersnake can grow to over 60 cm in total length.

Confusing Species
There are two other Gartersnakes found in BC. The Terrestrial Gartersnake has a yellow or brown stripe down the back, but has small black blotches on the back and sides. The two subspecies of the Common Gartersnake in British Columbia (the Valley Gartersnake and the Puget Sound Gartersnake) can be quite similar to the Northwestern Gartersnake but to a much larger size and are more apt to be black in background colour. The side stripes are confined to the second and third scale rows.

Distribution
The Northwestern Gartersnake is limited to southern coastal British Columbia and most of Vancouver Island. To the south it is also limited to the coast, south to northern California.

Habitat
Northwestern Gartersnakes occur in a variety habitats, but are generally associated with water. They are rarely found far from dense thickets.

Reproduction
Breeding occurs either in the spring or fall. As in all Gartersnakes, females no not lay eggs but give birth to their young. From 3-15 young are born during the summer. The young are 15-18 cm in total length at birth.

Natural History
The Northwestern Gartersnake eats a wide variety of animals including slugs, earthworms, fish, frogs and toads, small snakes, small mammals and birds. It is most active on sunny days. When approached it often moves quickly into the safety of thick vegetation.

Conservation Concerns
This species is relatively common where it occurs in BC and is considered to be not at risk.