How to identify it
Generally grayish-green back and yellow belly; pale (not white) stripes on the sides on the 2nd and 3rd scale rows above the belly scales. [1][2]
Mid-dorsal stripe is bright and runs the full body length in some areas, dull and fading at midbody in others; dark spots sometimes on the back; melanistic forms occur. [1][2]
Often two large blackish marks on the neck and irregular black marks on the belly. [1][2]
Usually 8 upper labials on each side, keeled dorsal scales and usually 21 scale rows at midbody. [1][2]
Total length to 109 cm, but few exceed 76 cm. [1][2]
Compared with the common gartersnake (thamnophis sirtalis): Common gartersnake has 7 upper labials, 19 scale rows at midbody and a uniformly dark head; terrestrial usually has 8 upper labials and 21 rows. [1][2]
Compared with the aquatic gartersnake (thamnophis atratus): Separate species (Rossman and Stewart 1987); the aquatic gartersnake is the stream-bound Pacific Coast snake. [1][2]
Species it is confused with
Check these before deciding what you are looking at. If you are not certain what it is, do not shoot.
- Common gartersnake · Thamnophis sirtalis
- Aquatic gartersnake · Thamnophis atratus
Where it lives
Often near lakes and slow streams but also in deserts, plains, mountains, meadows and forests, from sea level to about 3,990 m; hibernates in rocky areas. [1][2]
How it behaves
Diurnal: warms in the morning sun on heat-retaining surfaces, hunts through the day, and returns to shelter in the evening or in summer heat. [1][2]
Solitary while active but dens communally in winter, usually returning to the same rocky hibernation site each year. [1][2]
Coastal snakes mainly eat land prey (slugs, salamanders, small mammals, lizards); inland snakes hunt in and around water for frog and toad larvae, leeches and fish; hunts by movement and chemical cues. [1][2]
When threatened it secretes a foul-smelling chemical from the cloaca and musk glands. [1][2]
Limited legal take
Legal take of this species exists only under narrow conditions — a quota, a draw, a permit, a small area, or animals released or held on private land — set by the authorities below. Nowhere else is a legal opportunity implied, and Hunt shows one only where a certified rule establishes it.
Where legal take is listed
- California — reptile take · 2026 California Freshwater Sport Fishing Regulations (updated July 10, 2026), 14 CCR 5.05/5.60
- Colorado — reptile take · 2 CCR 406-7 Chapter W-7 Herpetofauna (03/04/2026; eff. 2026-05-01)
- Nevada — reptile take · CR 24-15 2025 & 2026 Seasons & Limits for Noncommercial Collection of Live, Unprotected Reptiles & Amphibians
- Utah — reptile take · Reptile and amphibian species classification tables (R657-53), updated Apr. 22, 2026
Being listed is not an open season. Seasons, zones, licences, methods and limits decide whether this animal may be taken on a given day and place — check Hunt or the authority before you go. Listings read 2026-09-30.
Where it is found
Northern Mexico (Baja California) through the western United States, from New Mexico to western Oklahoma and Nebraska, the Dakotas and the Canadian border west to the Pacific Coast; in Canada, central and southern Saskatchewan, Alberta and Manitoba.
Sources
Every claim above is attributed to one of these published sources.
NatureServe · reviewed 2026-09-30
NatureServe
University of Michigan Museum of Zoology · reviewed 2026-09-30
University of Michigan Museum of Zoology