Range in California: Red
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| Adult, 300 ft., Yuba County |
Adult, 2,600 ft., Sierra County |
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Sub-adults, Sierra County |
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| Adult, Butte County © Jackson Shedd |
Sub-adult, Sierra County |
Sub-adult, Sierra County |
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Juvenile, 4,500 ft., Kern County |
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Adult, 2,600 ft., Sierra County |
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| Adult, Sierra County |
Juvenile, Tulare County
© Patrick Briggs |
Habitat, mountain pond, 4,500 ft., Kern County |
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Habitat, mountain river, 2,600 ft., Sierra County
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Habitat, stream flowing from the eastern Sierras, 4,200 ft., Inyo County |
Habitat, mountain river, 2,600 ft., Sierra County |
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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 |
| 18 - 38 inches long (46 - 96 cm). Neonates are 5 - 6.5 inches long (12.7 - 16.5 cm). |
| Appearance |
A medium-sized slender snake with a head barely wider than the neck, a narrow snout, small eyes, and keeled dorsal scales. This snake is variable in appearance. The ground color is olive brown, dark brown, or blackish, and there are dark blotches on the back and upper sides which are obscured when the ground color is very dark. A light dorsal stripe may be present, but it is not distinct, except on the neck. LIght lateral stripes may or may not be present on the 2nd and 3rd scale rows. Northern populations of this snake have mottled black coloring below. This mottling is not present in southern populations.
Populations in streams draining into the Sacramento River all tend to lack lateral stripes. A melanistic population exists in Plum Creek, Tehama County. |
| Behavior |
Active during daylight. A highly-aquatic snake - more likely than most garter snake species to be found in the water. Can also be found basking at the edge of water or lying on mats of floating vegetation.Can be active 10 months of the year at lower elevations, but as few as 3 - 3.5 months at very high elevations.
Forages for food in slow-moving water and usully drags its captures on to shore to eat. Able to crawl on stream bottoms. When threatened, this snake will often strike repeatedly and release cloacal contents. |
| Diet |
| Eats mainly fish and amphibians and their larvae, including frogs, tadpoles, and aquatic salamander larvae. |
| Reproduction |
| Poorly known. Young are born live, apparently in late July. |
| Range |
| According to Rossman, Ford, and Siegel, this snake ranges from the Pitt and Sacramento rivers south along the Sierra Nevada Mountains to the western end of the Tehachapi Mountains, with outlier populations along major rivers in west-central Nevada and the Owens Valley, at elevations from 300 - 8,000 ft. (91 - 2438 m). |
| Habitat |
| Associated with water - seasonal creeks, large mountain rivers, meadow ponds, and small lakes, in montane coniferous forests, oak woodlands, chaparral, pine juniper, and sagebrush. Prefers areas with rocks and vegetation. |
| Taxonomic Notes |
According to Stebbins, T. couchi hybridizes with the Oregon Gartersnake -Thamnophis atratus hydrophilus, in the Pit River drainage and with the Two-striped Gartersnake -Thamnophis hammondii, at the western end of the Tehachapi Mountains.
T. couchii was formerly a composite of four species of gartersnakes: T. atratus, T. couchii, T. gigas, and T. hammondii, until 1987. |
| Conservation Issues (Conservation Status) |
| Not known to be threatened, but may be negatively impacted by competition with introduced bullfrogs and non-native fish in some areas. |
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Taxonomy |
| Family |
Colubridae |
Colubrids |
| Genus |
Thamnophis |
North American Gartersnakes |
Species
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couchii |
Sierra Gartersnake |
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Original Description |
Thamnophis couchii - Baird, 1854 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 7, p. 62
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
couchii - honors Couch, Darius N.
from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
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Alternate Names |
Western Aquatic Garter Snake,
Sierra Garter Snake
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| Other California Gartersnakes |
T. a. atratus - Santa Cruz Gartersnake
T. a. hydrophilus - Oregon Gartersnake
T. a. zaxanthus - Diablo Range 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. infernalis - California Red-sided 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.
Bartlett, R.D. , & Alan Tennant. Snakes of North America - Western Region. Gulf Publishing Co., 2000.
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.
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.
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.
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Organization
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Status Listing
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| U.S. Endangered Species Act (ESA) |
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| California Endangered Species Act (CESA) |
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| California Department of Fish and Game |
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| Bureau of Land Management |
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| USDA Forest Service |
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| Natureserve Global Conservation Status Ranks |
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World Conservation Union - IUCN Red List
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