How to Identify the Northwestern Garter Snake (Identification Guide)

Key identifying features

The Northwestern Garter Snake (Thamnophis ordinoides) is a small, slender garter snake known for its remarkable variability in color and pattern, making it one of the most visually diverse snake species in North America. Identification depends more on body proportions, scale texture, and range than on a single fixed color scheme.

Coloration & pattern

Background color can be black, brown, gray, or olive, and the vertebral stripe—when present—may be any of several colors including bright orange, red, yellow, blue, white, or greenish, sometimes bordered by darker pigment for contrast. Some individuals show no stripe at all, instead displaying scattered spots, longitudinal streaks, or a nearly checkered pattern. Lateral stripes are often faint, reduced, or missing entirely, which is a useful distinguishing trait since many other garter snakes show more consistent triple-striping. The belly is usually pale gray or bluish, sometimes with dark spotting.

Head, eyes & scales

The head is small and only slightly wider than the neck. Eyes are proportionate with round pupils. Dorsal scales are keeled but the species is notably smooth and slender in overall texture compared to bulkier garter snakes, with 17 scale rows at midbody, fewer than many related species.

Size & body shape

This is one of the smaller garter snakes, with adults typically reaching only 18 to 26 inches (46-66 cm). The body is slim and the tail relatively long and tapering, giving the snake an overall delicate, wiry appearance.

Range & habitat where you'll see it

The Northwestern Garter Snake is found along the Pacific coast from British Columbia south through Washington, Oregon, and into northern California, generally west of the Cascade crest. Unlike many garter snakes, it is often found well away from water, favoring grassy fields, forest edges, gardens, and coastal scrub.

How to tell it apart from look-alikes

Its notably smaller size, slimmer build, and reduced scale row count (17 versus 19-21 in many relatives) help separate it from the Western Terrestrial and Common Garter Snakes. The extraordinary variability of the vertebral stripe color, sometimes shifting to vivid oranges, reds, or blues within the same population, is a hallmark rarely matched by other garter snake species. Its tendency to be found in dry grassy or wooded habitat away from permanent water, rather than always near streams, is another helpful clue given the broader group's usual water association.