CaliforniaHerps.com

A Guide to the Amphibians
and Reptiles of California


Coast Gartersnake - Thamnophis elegans terrestris

Fox, 1951
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Terrestrial Gartersnakes California Range MapRange in California: Purple

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to the other subspecies


observation link





Coast Gartersnakes with Light Dorsal and Side Stripes and Black and Red Sides
Coast Gartersnake
Adult, Napa County
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
  Adult, San Mateo County   Adult, San Mateo County
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Adult, Monterey County Adult, Marin County Adult, bulging from a recent meal,
Marin County
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Adult, Marin County (San Rafael) Adult, Humboldt County Adult, Humboldt County
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Adult and juvenile, Lodi, San Joaquin County © Patrick Briggs Adult, San Francisco County © Zach Lim
Coast Gartersnake Coast Gartersnake Diablo Range Gartersnake Coast Gartersnake
Adult, Del Norte County © Alan D. Barron Adult, San Francisco County © Zach Lim Adult, southern Napa County.
Valley Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Adult, San Francisco County
© Luke Talltree
Adult with lots of red, San Mateo County 
© Luke Talltree
Adult, Marin County
Coast Gartersnake San Francisco Gartersnake Coast Gartersnake  
Large old adult, San Mateo County
A Coast Gartersnake (right) basks in dry grass next to a San Francisco Gartersnake (left) that is emerging from a gopher hole in San Mateo County.
© Zach Lim
This picture shows some of the variety of colors and patterns seen in a single population of this snake. All three snakes were all found at the same location in San Mateo County.  © John Worden  
       
Coast Gartersnakes with a Lot of Red on the Side Stripes
Coast Gartersnake
Adult with mostly red side stripes, San Mateo County © James Maughn
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Juvenile, Alameda County Adult, Contra Costa County Adult, Contra Costa County
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
  Adult, Monterey County   Wide red-striped adult, Santa Cruz County. © Susannah Goldston
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Adult, Monterey County Adult, Santa Cruz County
© Benjamin German
Adult, Humboldt County
Diablo Range Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Adult, Santa Cruz County © Zach Lim Adult, Santa Cruz County
© 2005 Brad Alexander
Adult, Marin County (San Rafael)
Diablo Range Gartersnake Diablo Range Gartersnake Coast Gartersnake Coast Gartersnake
This adult from Santa Clara County has red on all three stripes. © Holly Brown Adult, San Mateo County © Jared Heald Adults, San Mateo County
© Jared Heald
Coast Gartersnake Coast Gartersnake Coast Gartersnake Valley Gartersnake
Adult, San Mateo County © Jared Heald Adult, San Mateo County © Jared Heald Adult, San Mateo County © Jared Heald Adult, San Mateo County © Jared Heald
       
Coast Garternakes with Little or No Red Coloring
Coast Gartersnake Coast Gartersnake Coast Gartersnake Diablo Range Gartersnake
Adult, with no red,
San Luis Obispo County
Adult, Humboldt County Adult, Humboldt County Adult, San Luis Obispo County
© Patrick Briggs
Coast Gartersnake Coast Gartersnake Coast Gartersnake Coast Gartersnake
Adult, Humboldt County Adult, Del Norte County © Alan D. Barron
Diablo Range Gartersnake Diablo Range Gartersnake Diablo Range Gartersnake Coast Gartersnake
Adult, Monterey County.
© Van Wishingrad
Adult, Monterey County.
© Van Wishingrad
Swimming adult, Monterey County.
© Van Wishingrad
A dark, bluish adult with only a few red spots from Santa Cruz County.
© James Maughn
Coast Gartersnake Coast Gartersnake    
Adult with little red, Marin County 
© Luke Talltree
Adult with no red coloring, in a defensive pose, Santa Barbara County
@ Jeff Hopkins.
   
       
Juvenile Coast Gartersnakes
Coast Gartersnake Coast Gartersnake Coast Gartersnake Diablo Range Gartersnake
Juvenile, Marin County Juveniles found under the same board in Alameda
County, with two different color patterns.
Juvenile, San Mateo County © Zach Lim
Coast Gartersnake Coast Gartersnake    
Juvenile, Del Norte County © Alan D. Barron    
       
Comparisons With Sympatric Gartersnakes
Gartersnakes Gartersnakes Gartersnakes Gartersnakes
Three species found at the same Marin County location, including Thamnophis atratus, and Thamnophis sirtalis.
© Zach Lim
Three species found at the same Marin County location, including Thamnophis atratus, and Thamnophis sirtalis.
© Luke Talltree

Marin County snakes:
Coast Gartersnake on top.
Aquatic Gartersnake on bottom.

Marin County snakes:
Aquatic Gartersnake on left.
Coast Gartersnake on bottom.
       
Coast Gartersnakes Feeding
Coast Gartersnake Coast Gartersnake Coast Gartersnake  
Adult eating a saltwater fish it found stranded in a tide pool on a rocky beach below the high tide mark in San Luis Obispo County © Randy Pickard Adult, San Mateo County, eating a bird,
found by Zach Mumbach,
Photo © Aaron Reif
 
Coast Gartersnake Coast Gartersnake Coast Gartersnake  
A coast gartersnake eating a California Towhee in Santa Cruz County.
The meal looks too big for the snake, but the outcome is unknown © Scott Peden
 
Northern Pacific Rattlesnake Northern Pacific Rattlesnake Coast Gartersnake  
Janet heard squeaking then saw a gartersnake rolling and twisting down an incline. When they stopped, the snake was the victor in a struggle with a vole. Solano County. © Janet Ellis Adult, San Mateo County, eating a Banana Slug © Rory Doolin  
       
Habitat
Coast Gartersnake Habitat Coast Gartersnake Habitat Coast Gartersnake Habitat Coast Gartersnake Habitat
Coastal habitat,
Monterey County
Habitat, San Luis Obispo County Coastal pond habitat,
San Mateo County
Riparian woodland habitat,
Contra Costa County
Coast Gartersnake Habitat Coast Gartersnake Habitat Coast Gartersnake Habitat Coast Gartersnake Habitat
Coastal riparian habitat, Marin County Forest habitat, Humboldt County Coastal meadow habitat,
Humboldt County
Habitat, Alameda County
Coast Gartersnake Habitat Coast Gartersnake Habitat Mountain Gartersnake Habitat
Coastal pond habitat,
San Mateo County
Habitat, Santa Cruz County
© Colin Byrne
Coastal habitat, Monterey County Habitat, Santa Cruz Mountains
© Zachary Lim
Coast Gartersnake Habitat Coast Gartersnake Habitat    
San Francisco County Habitats © Zachary Lim    
       
Short Video
  Coast Gartersnake  
  A couple of snakes from the coast of Marin County, doing what snakes do -
trying to get away from an annoying human with a video camera. They finally did.
 
   
Description

Not Dangerous (Non-poisonous)  -  This snake does not have venom that is dangerous to most humans.

Gartersnakes have toxins in their saliva which can be deadly to their prey and their bite might produce an unpleasant reaction in humans, but they are not considered dangerous to humans.

Size
Thamnophis elegans measures 18 - 43 inches in length (46 - 109 cm).

Appearance
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.
Key to Identifying California Gartersnake Species

Life History and Behavior

Activity
Active in daylight.
Chiefly terrestrial - not as dependant on water as other gartersnake species, but more likely to be found near water.
Defense
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
This snake eats a wide range of prey (among the widest of any snake species), including amphibians and their larvae, fish, birds, mice, lizards, snakes, worms, leeches, slugs, and snails.
Breeding
Breeds primarily in spring, with young born live July - Sepember.

Habitat
Inhabits mixed woodland, grassland, coniferous forest, dunes, brushland, generally in the vicinity of ponds or flowing water.

Geographical Range
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 maps to show T. e. terrestris there based on the one bright red snake from Lodi seen above, but discussions with a herpetologist in that area have convinced me that they are T. e. elegans. It's likely that the wild-caught Lodi specimen was transported there.

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.

Full Species Range Map
Elevational Range
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 with T. 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.

Three subspecies of Thamnophis elegans are found in California - T. e. vagrans - Wandering Gartersnake, T. e. e.egans - Mountain Gartersnake, and T. e. terrestris - Coast Gartersnake.

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.


Alternate and Previous Names (Synonyms)

Thamnophis elegans terrestris - Coast Garter Snake (Stebbins 1966, 1985, 2003, Stebbins & McGinnis 2012)
Thamnophis elegans hueyi (Stebbins 1954)
Thamnophis elegans terrestris - Coastal California garter snake (Fox 1951)

Conservation Issues  (Conservation Status)
This species is not known to be threatened, but gartersnakes have been negatively impacted by competition with introduced bullfrogs and non-native fish in some areas.
Taxonomy
Family Colubridae Colubrids Oppel, 1811
Genus Thamnophis North American Gartersnakes Fitzinger, 1843
Species elegans Western Terrestrial Gartersnake (Baird and Girard, 1853)
Subspecies

terrestris Coast Gartersnake Fox, 1951
Original Description
Thamnophis elegans - (Baird and Girard, 1853) - Cat. N. Amer. Rept., Pt. 1, p. 34
Thamnophis elegans terrestris - Fox, 1951 - Univ. California Publ. Zool., Vol. 50, p. 499, fig. 3

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name
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

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Other California Gartersnakes
T. a. atratus - Santa Cruz Gartersnake
T. a. hydrophilus - Oregon Gartersnake
T. a. zaxanthus - Diablo Range Gartersnake
T. couchii - Sierra Gartersnake
T. gigas - Giant Gartersnake
T. e. elegans - Mountain Gartersnake
T. e. vagrans - Wandering Gartersnake
T. hammondii - Two-striped Gartersnake
T. m. marcianus - Marcy's Checkered Gartersnake
T. ordinoides - Northwestern Gartersnake
T. s. fitchi - Valley Gartersnake
T. s. infernalis - California Red-sided Gartersnake
T. s. tetrataenia - San Francisco Gartersnake

More Information and References
California Department of Fish and Wildlife

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.

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.


Conservation Status

The following status listings are copied from the 2017 Special Animals List and the 2017 Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.

If no status is listed here, the animal is not included on either CDFW 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.

Check here to see the most current complete lists.


This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
Organization
Status Listing
NatureServe Global Ranking
NatureServe State Ranking
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife None
Bureau of Land Management None
USDA Forest Service None
IUCN

 

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