West Coast Garter Snake
Thamnophis atratus
A common streamside garter snake of the Pacific coast, often seen basking near rivers and creeks in California and Oregon.
- Venomous?
- Mildly venomous
- Adult length
- 0.6-1.0 m (2-3.3 ft)
- Range
- Western United States (Oregon to California)
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Overview
The West Coast garter snake is a widespread and frequently encountered species along rivers, streams, and coastal habitats from Oregon through much of California. It is closely tied to permanent water sources and is one of the more aquatic garter snakes in the region.
Several subspecies are recognized across its range, varying somewhat in color pattern from more heavily striped to more uniformly dark forms.
How to identify it
- Dark olive, brown, or blackish dorsal coloring, sometimes with a faint yellowish or orange dorsal stripe
- Variable presence of side stripes depending on subspecies
- Keeled scales
- Round pupils
- Distinguished from other California garter snakes by darker overall tone and strong association with flowing water
Habitat & range
Common along rivers, streams, and adjacent riparian vegetation from southern Oregon through California, from lowlands into foothill elevations.
Behavior, diet & reproduction
Diurnal and highly aquatic, often seen swimming or basking on rocks along stream banks. Feeds on fish, tadpoles, and frogs. Mild venom aids in subduing prey, not dangerous to humans. Bears live young in summer.
Frequently asked questions
Where is the West Coast garter snake commonly seen?
Along rivers and streams from Oregon through California, often basking on rocks near water.
Is it dangerous to humans?
No, it has only mild venom for prey and poses no real threat to people.
What does it eat?
Mainly fish, tadpoles, and frogs found in and near streams.
Are there different forms of this species?
Yes, several subspecies vary in color pattern across its range, from striped to more uniformly dark.
West Coast Garter Snake guides
In-depth guides for identifying and understanding West Coast Garter Snake.
