Santa Cruz Garter Snake

Thamnophis atratus (Kennicott, 1860)

Alternate Name Pacific Coast Aquatic Garter Snake
Spanish Name Culebra de Agua Nómada Occidente
Max. Recorded Length 101.6 cm / 40 inches
Range California, Oregon
Pet Trade Availability ★★★☆ frequently available
Captivity Rating ★★★☆ good

Note: These species pages are in various stages of completion. Some are basically finished; others are very much under construction. Please be patient while I work on this section.




Three subspecies are currently recognized:

  1. Santa Cruz Garter Snake, Thamnophis atratus atratus (Kennicott, 1860)
  2. Oregon Garter Snake, T. a. hydrophilus Fitch, 1936
  3. Diablo (Broad-striped) Garter Snake, T. a. zaxanthus Boundy, 1999

The Santa Cruz Garter Snake is found in central and southern California. This subspecies has two color morphs: one with a single stripe along the back, and a three-striped morph more typical of garter snakes. The Oregon Garter Snake is found in northern California and Oregon; it’s not nearly as striking as T. a. atratus. A new subspecies described in 1999, the Diablo (Broad-striped) Garter Snake is found in the highlands between Napa and Santa Barbara counties (whereas T. a. atratus is found along the coast).

Invalid Subspecies

The Aquatic (Coast) Garter Snake, Thamnophis atratus aquaticus Fox 1951, is now considered an intergrade of T. a. atratus and T. a. hydrophilus.

Captive Care

Thamnophis atratus is the only one of the western aquatic species found in any numbers in the pet trade. The one-striped morph of T. a. atratus is of particular interest to garter snake breeders.

I have no experience with this species. (It’s done. See Rossi.)

If you have experience with this species and would like to share, please contact me.

For general information on keeping garter snakes in captivity, please see the Care Guide.

Articles and News


Bartlett, R. D. and Alan Tennant. 1997. Snakes of North America: Western Region. Houston: Gulf.

Bol, Steven. “Breeding and care in captivity of the Santa Cruz Garter Snake, Thamnophis atratus atratus (Kennicott, 1860).”

Brown, Philip R. 1997. A Field Guide to Snakes of California. Houston: Gulf.

Ernst, Carl H. and Evelyn M. Ernst. 2003. Snakes of the United States and Canada. Washington: Smithsonian Books.

Rossi, John V. and Roxanne Rossi. 2003. Snakes of the United States and Canada: Natural History and Care in Captivity. Malabar FL: Krieger.

Rossman, Douglas A., Neil B. Ford and Richard A. Seigel. 1996. The Garter Snakes: Evolution and Ecology. Norman OK: University of Oklahoma Press.

St. John, Alan. 2002. Reptiles of the Northwest. Edmonton: Lone Pine.