Range in California: Red
Click the map for a guide
to the other subspecies.
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Adult 1, Marin County |
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Adult 2, Marin County |
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Large adult, Monterey County. Photos © Gary Nafis. Specimen courtesy of David Keegan & Susan Whitford of the Santa Lucia Conservancy. |
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Adult 1, Humboldt County |
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Adult 2, Humboldt County |
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Adult, Contra Costa County |
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Habitat |
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Habitat, Marin County
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Habitat, San Diego County
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Habitat, Marin County |
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Habitat, (winter) Monterey County. |
Habitat, Humboldt County |
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Short Video |
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A huge feisty Red-sided Gartersnake from Santa Barbara County strikes out a few times at its captor.
Video © Vince Semonsen
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Description |
Nonvenomous |
| 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 |
| Adults of this species measure 18 - 55 inches in length (46 - 140 cm), but the average size is under 36 inches (91 cm). |
| Appearance |
A medium-sized snake with a head barely wider than the neck and keeled dorsal scales.
Ground color is dark olive to black. The dorsal stripe is wide and well-defined, and yellowish to bluish in color. Light stripes along the lower sides are not very distinct, often blending in with the color of the belly. There are red bars alternating with the ground color along the sides above the lateral stripes. The head is red or orangish. The underside is bluish gray, sometimes very blue north of the Bay Area (shown above) and may have some dark coloring. The eyes are relatively larged compared with other gartersnake species. |
| Behavior |
| Primarily active during daylight. A good swimmer. Often escapes into water when threatened. When first handled, typical of gartersnakes, this snake often releases cloacal contents and musk, and strikes. The species T. sirtalis is capable of activity at lower temperatures than other species of North American snake. |
| Diet |
| Eats a wide variety of prey, including amphibians and their larvae, fish, birds, and their eggs, small mammals, reptiles, earthworms, slugs, and leeches. This snake is able to eat adult Pacific newts (Taricha) which are deadly poisonous to most predators. |
| Reproduction |
| Mating occurs in the spring (and possibly the fall ) and young are born live, spring to fall. |
| Range |
This subspecies is endemic to California, ranging from Humboldt County south, along the coast ranges (excluding much of the San Francisco peninsula) and east of the San Francisco Bay to just below the Monterey Bay where T. s. fitchi takes over. Continues from where T. s. fitchi drops out in Santa Barbara county south along the coast to San Diego County. (Snakes from the Santa Clara River area in Ventura County south, may prove to be a new species [Stebbins]).
T. sirtalis has the largest distribution of any gartersnake, ranging from the east coast to the west coast and north into Canada, farther north than any other species of snake in North America.
We are following Rossman et al. for the range of T. sirtalis along the central coast. Stebbins and others show the range of T. s. infernalis continuing south of Monterey Bay through the coast ranges south of the Bay Area to San Diego County. Here is an alternate map showing this distribution. |
| Habitat |
| Utilizes a wide variety of habitats - forests, mixed woodlands, grassland, chaparral, farmlands, often near ponds, marshes, or streams. |
| Taxonomic Notes |
In 1995, Doug Rossman and Jeff Boundy re-named the Thamnophis sirtalis found on the San Francisco Peninsula T. s. infernalis, (removing the name T. s. tetrataenia, but recognizing that the snakes were still subspecifically distinct), and lumped the coastal T. sirtalis with T. s. concinnus. This taxonomy is shown on the range map in the 1996 book, The Garter Snakes - Evolution and Ecology 1. In 1998, Sean Barry and Mark Jennings petitioned the International Commission on Zoological Nomenclature (ICZN) to restore the previous nomenclature 2. With no opposition from Boundy or Rossman, the ICZN agreed to restore the name T. s. tetrataenia to snakes on the San Francisco peninsula 3. Nevertheless, some authors either missed the restoration of this nomenclature or chose to ignore it, and their work still reflects Rossman and Boundy's nomenclature.
(Thanks to Sean Barry for this clarification)
The South Coast Gartersnake
Southern California Common Garter Snakes have been treated as a unique taxon - Thamnophis sirtalis ssp. - South Coast Gartersnake, but the recognition of this subspecies is rare. The only published description I can find is in the following paper:
Jennings, Mark R.
and Marc P. Hayes. Amphibian and Reptile Species of Special Concern in California. California Department of Fish and Game, published November 1, 1994.
The information about this snake that was published in the paper can be found here. (Since the Dept. of Fish and Game occasionally changes the addresses on their website, you may have to search for it if the link above does not work.)
Jennings and Hayes state that this snake is known from scattered localities from the Santa Clara River Valley in Ventura County south to the vicinity of San Pasqual in San Diego County. It is restricted to marsh and upland habitats near permanent water with good strips of riparian vegetation where adequate prey and refuge can be found.
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| Conservation Issues (Conservation Status) |
None for the northern population.
The California Department of Fish and Game lists the South Coast Gartersnake as a California Species of Special Concern. Jennings and Hayes (in the 1994 paper cited above) state that 75 percent of the known historic localities for this snake no longer support snakes due to habitat loss from urbanization and flood control projects, floods, extended droughts, and introduced aquatic predators. |
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Taxonomy |
| Family |
Colubridae |
Colubrids |
| Genus |
Thamnophis |
North American Gartersnakes |
| Species |
sirtalis |
Common Gartersnake |
Subspecies
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infernalis |
Red-sided Gartersnake |
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Original Description |
Thamnophis sirtalis - (Linnaeus, 1758) - Syst. Nat., 10th ed., Vol. 1, p. 222
Thamnophis sirtalis infernalis - (Blainville, 1835) - Nouv. Ann. Mus. Hist. Nat. Paris, Vol. 4, p. 291, pl. 26, fig. 3
from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
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Meaning of the Scientific Name |
Thamnophis - Greek - thamnos - shrub or bush, and ophis - snake, serpent
sirtalis - sirtalis like a garter - probably refers to the to striped pattern
infernalis - Latin - of hell
from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
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Alternate Names |
Boundy and Rossman classify T. s tetrataeia as T. s. infernalis with T. s. infernalis becoming T. s. concinnus.
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Other California Garternakes |
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. terrestris - Coast 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. tetrataenia - San Francisco Gartersnake
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More Information and References |
Natureserve Explorer
California Dept. of Fish and Game
Rossman, Douglas A., Neil B, Ford, & Richard A. Siegel. The Garter Snakes - Evolution and Ecology. University of Oklahoma press, 1996.
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., & F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
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.
Brown, Philip R. A Field Guide to Snakes of California. Gulf Publishing Co., 1997.
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The following status listings come from the Special Animals List which is published several times each year by the California Department of Fish and Game.
This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California, but populations along the coastal plain from Ventura County to San Diego County are listed as a separate subspecies by the Special Animals List - T. sirtalis ssp. - the South Coast Garter Snake, with the status listings shown below.
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Organization
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Status Listing
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| U.S. Endangered Species Act (ESA) |
None |
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| California Endangered Species Act (CESA) |
None |
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| California Department of Fish and Game |
SSC |
California Species of Special Concern |
| Bureau of Land Management |
None |
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| USDA Forest Service |
None |
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| Natureserve Global Conservation Status Ranks |
G5T1T2 S1S2 |
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World Conservation Union - IUCN Red List
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None |
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