These are all Coast Gartersnakes but because the subspecies is so variable in appearance I have separated the pictures into four sections - three loosely-defined color and pattern types of adults, plus juveniles.
Coast Gartersnakes with Light Dorsal and Side Stripes and Black and Red Sides
A medium-sized slender snake with a head barely wider than the neck and keeled dorsal scales. Some scale averages:
Average of 8 upper labial scales, occasionally 7, scales 6 and 7 are enlarged, higher than wide.
Average of 10 lower labial scales.
The front and rear pair of chin shields are equal in length.
The internasals are wider than long and not pointed in front.
Average scale count at mid-body is 21, rarely 19.
Color and Pattern
Color and pattern is highly variable, but there is usually a yellow dorsal stripe and a yellowish stripe along the bottom of each side.
The underside is yellowish to bluish-gray with varying amounts of reddish markings.
One color phase consists of a yellow dorsal stripe and two distinct yellowish or whitish side stripes, with black checkered spots on the sides inbetween the stripes on a reddish ground color, creating a red and black checkerboard appearance.
This phase occurs primarily on the San Francisco peninsula and north along the coast into Marin County and possibly farther.
On some snakes in the Santa Cruz Mountains and the Monterey Bay area, the side stripes are red, with varying degrees of checkering or barring of the black on a reddish ground color.
On some snakes the ground color is almost completely solid dark, the dorsal stripe is yellow, but the side stripes are reddish. We include pictures here of this phase from the East Bay hills, the Santa Cruz Mountains, and southeast Marin County near the S.F. bay.
Another color phase consists of almost completely solid dark coloring between distinct light side and dorsal stripes, with little or no red.
This phase is common on juveniles and seems to be most common on adults from Santa Cruz County south.
Along the far north coast in Humboldt and Del Norte Counties, the dark coloring can be light brown with little red, or there can be a heavy red wash over the sides.
Snakes there can also have three yellowish stripes, a reddish ground color with some black markings, and a dark bar beneath each side of the dorsal stripe.
Active in daylight.
Chiefly terrestrial - not as dependant on water as other gartersnake species, but more likely to be found near water.
When frightened, this species will sometimes seek refuge in vegetation or ground cover, but it will also crawl quickly into water and swim away from trouble.
If frightened when picked up, this snake will often strike repeatedly and release cloacal contents and musk.
Diet and Feeding
Western Terrestrial Gartersnakes - Thamnophis elegans - eat a wide range of prey (among the widest of any snake species - Rossmann, et al. 1996.) The prey depends on the size of the snake (large snakes tend to eat larger prey, small snakes can only eat smaller prey) and what prey is available. Populations found on the humid North Coast where slugs are abundant are genetically predisposed to eat slugs, while populations in dryer areas where slugs are less common refuse to eat slugs when they are offered. (Rossmann, et al. 1996.)
Diet includes: invertebrates such as slugs, leeches, snails, and earthworms; fish; amphibians - tadpoles, frogs, (and probably salamanders); snakes and lizards; birds; and small mammals such as mice and voles.
Thamnophis elegans terrestris has been found eating Taricha torosa, which are deadly poisonous to most predators, in San Luis Obispo County.
(Feldman, Hansen, & Sikola. Herpetological Review 51 2020.)
There is evidence * that when Common Gartersnakes (Thamnophis sirtalis) eat Rough-skinned Newts (Taricha granulosa) they retain the deadly neurotoxin found in the skin of the newts called tetrodotoxin for several weeks, making the snakes poisonous (not venomous) to predators (such as birds or mammals) that eat the snakes. Since California Newts (Taricha torosa) also contain tetrodotoxin in their skin, and since gartersnake species other than T. sirtalis also eat newts, it is not unreasonable to conclude that any gartersnake that eats either species of newt is poisonous to predators.
Joseph Grinnell and Charles Lewis Camp. A Distributional List of the Amphibians and Reptiles of California. University of California Publications in Zoology Vol. 17, No. 10, pp. 127-208. July 11, 1917.
Mates primarily in spring, with young born live from July to Sepember.
Inhabits mixed woodland, grassland, coniferous forest, dunes, brushland, generally in the vicinity of ponds or flowing water.
The species Thamnophis elegans - Western Terrestrial Gartersnake, ranges widely from the California coast north through most of northern California, Oregon, Washington, Idaho and Montana, into Canada, including Vancouver Island, British Columbia, Alberta and Saskatchewan, and east into the states of Wyoming, Colorado, Utah, Arizona and New Mexico and just barely making it into South Dakota, Nebraska, and Oklahoma. Many isolated populations exist, including those in the San Bernardino Mountains and one in Baja California Norte, Mexico (the San Pedro Martir Gartersnake.)
This subspecies, Thamnophis elegans terrestris - Coast Gartersnake, occurs along the Pacific coast from southern Oregon to Ventura County.
Most range maps showing subspecies of T. elegans, show T. e. elegans occurring in the Central Valley near Lodi. Previously I changed my range map to show a small population of T. e. terrestris there based on pictures of a bright red snake found in Lodi, but discussions with a herpetologist familiar with that area have convinced me that only T. e. elegans is found in the San Joaquin Valley. It's likely that the wild-caught Lodi specimen was transported there by somebody.
A range of intergradation is traditionally shown running the length of the Sierra Nevada mountains, but I am not certain exactly where or how wide it is.
The species Thamnophis elegans - Western Terrestrial Gartersnake, occurs from sea level to 13,100 ft. (3,990 m) in elevation in Colorado. (Stebbins, 2003)
Notes on Taxonomy
T. e. vagrans intergrades withT. e. elegans in northeast California in Modoc and eastern Siskiyou counties and in south central Oregon (this snake was formerly classified as the subspecies Thamnophis elegans biscutatus - Klamath Gartersnake. Intergrades with T. e. elegans also occur along the southern and southeastern edge of the Sierras.
Rossman, Ford, and Seigel (1996) emphasize that a detailed study of geographic variation throughout the range of Thamnophis elegans is badly needed.
Bronikowski and Arnold (2001, Copeia 2001:508-513) found several clades within T. elegans that do not always follow the subspecies boundaries, and concluded that there was no support for the race terrestris. Presumably, the former T. e. terrestris snakes become T. e. elegans.
Hammerson (1999, Amphibians and Reptiles of Colorado. 2nd ed. Univ. of Colorado Press) synonymized T. e. arizonae and T. e. vascotanneri but retained three subspecies, T. e. vagrans, T. e. elegans, and T. e. terrestris.
Thamnophis - Greek - thamnos - shrub or bush, and ophis - snake, serpent
elegans - Latin - fine or elegant -- "delicately carinated" terrestris - Latin - of the earth - probably refers to the hatitat and the terrestrial nature
Rossman, Douglas A., Neil B, Ford, & Richard A. Siegel. The Garter Snakes - Evolution and Ecology. University of Oklahoma press, 1996.
Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.
Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.
Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021.
Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018.
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.
Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Snakes of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.
Bartlett, R. D. & Alan Tennant. Snakes of North America - Western Region. Gulf Publishing Co., 2000.
Brown, Philip R. A Field Guide to Snakes of California. Gulf Publishing Co., 1997.
Ernst, Carl H., Evelyn M. Ernst, & Robert M. Corker. Snakes of the United States and Canada. Smithsonian Institution Press, 2003.
Wright, Albert Hazen & Anna Allen Wright. Handbook of Snakes of the United States and Canada. Cornell University Press, 1957.
The following conservation status listings for this animal are taken from the October 2021 California "Special Animals List" and the October 2021 "State and Federally Listed Endangered and Threatened Animals of California" list, both of which are produced by multiple agencies and available here: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. You can check the link to see if there are more recent lists.
If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can go to the NatureServe and IUCN websites to check their rankings.
This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.