California Reptiles & Amphibians

Thamnophis hammondii - Two-striped Gartersnake



Click on a picture for a larger view




Range in California: Red




Adult, San Diego County
 
Young adult, spotted morph, Cottonwood Creek, San Diego County
Adult, striped morph, Santa Barbara County © Brian Hubbs
Adult, spotted morph (with faint stripes), Laguna Mountains,
San Diego County © John Stoklosa
Sub-adults, two color phases, Ventura County. © Brian Hubbs
Adult, Santa Barbara County
© Jason Butler
An adult snake with a reddish stripe from just west of the Piru River in Ventura County. © Vince Semonsen
Adult, Ventura County © Jeremy Huff
Steve Ivie and his Cub Scout troup saw this snake enter a river in the San Gabriel Mountains of Los Angeles County. They watched the snake swim upstream and grab a trout about 8 or 9 inches in length, then drag the trout onto a rock at the edge of the river, and eat it, as you can see above. © Steve Ivie

Steve Ivie and his Cub Scout troup saw this adult Two-striped Gartersnake snake enter a river, swim upstream, and grab a trout about 8 or 9 inches in length. The snake then dragged the trout onto a rock at the edge of the river, and eat it. © Steve Ivie
Adult from the Mohave Desert at Victorville, San Bernardino County
© Michael Clarkson
Adult, Ventura County © Patrick Briggs
 
This snake typically has a single light stripe low on each side.
Sign, San Diego County park
 
Habitat
Habitat, coastal sage, San Diego County
Habitat, desert creek, San Diego County
Habitat, San Diego County mountain meadow
Habitat, coastal river, San Diego County
Habitat, San Gabriel Mountains,
Los Angeles County
Habitat, 5,200 ft., San Gabriel Mountains, Los Angeles County

   
 
Habitat, Ventura County. © Brian Hubbs
 
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
24 - 40 inches long (61 - 102 cm). Most often 18 - 30 inches long (46 - 76 cm). Neonates are 7.5 - 9 inches (19 - 23 cm).
Appearance
A medium-sized snake with a head barely wider than the neck and keeled dorsal scales. Appearance is variable - there are two basic pattern morphs. Both have a drab olive, brown, or dark gray ground color, with no dorsal stripe, except for a spot on the neck. The striped morph has a yellowish to gray lateral stripe on each side, and a fairly uniform dorsal coloring, with only faint spotting. The unstriped morph lacks the lateral stripes and has two rows of small dark spots on each side. Light areas between the scales between these spots can create a checkered appearance (as seen in some of the pictures above.) The underside is pale yellow or orange, unmarked, or with dark smudging.

A dark morph is found along the outer coast in San Luis Obispo County. A dark green and a reddish color morph occur along the Piru River in Ventura County. A melanistic population occurs on Catalina Island.
Behavior
Primarily aquatic. Diurnal. Also active at night and at dusk during hot weather in some areas. Can be active from January to November depending on weather conditions.

Most gartersnakes, when picked up, will often strike repeatedly and release cloacal contents and musk.
Diet
Eats tadpoles, newt larvae, small frogs and toads, fish, and occasionally worms and fish eggs. Probably forages for food in and under water.
Reproduction
Breeding has been observed in late March and early April, with live young born in late July and August.
Range
Ranges continuously from near Salinas in Monterey County south along the coast mostly west of the south Coast Ranges, to southern California where it ranges east through the Transverse Ranges (and into the desert in Victorville) and south through the Peninsular Ranges into northern Baja California. Occurs in southern Baja in isolated areas. Also occurs on Catalina Island. At elevations from sea Level to 6,988 ft. (2130 m).
Habitat
Generally found around pools, creeks, cattle tanks, and other water sources, often in rocky areas, in oak woodland, chaparral, brushland, and coniferous forest.
Taxonomic Notes
Formerly classified as a subspecies of Thamnophis couchii.
T. digueti was synonymized with T. hammondii by McGuire and Grismer (1993, Herpetologica 49:354-365).

The Santa Catalina population of T. hammondii is treated as a distinct subspecies by the California Dept. of Fish and Game - Santa Catalina garter snake, Thamnophis hammondii ssp.
Conservation Issues  (Conservation Status)
Protected by the state. Loss of wetland habitats have contributed to a reduction in the range of this snake.

The California Dept. of Fish and Game lists the Santa Catalina garter snake, Thamnophis hammondii ssp. - as a California Species of Special Concern.

Taxonomy
Family Colubridae Colubrids
Genus Thamnophis North American Gartersnakes
Species


hammondii Two-striped Gartersnake
Original Description
Thamnophis hammondii - (Kennicott, 1860) - Proc. Acad. Nat. Sci. Philadelphia, Vol. 12, p. 332

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
hammondii
- honors Hammond, William A.

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

Alternate Names
None

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. terrestris - Coast Gartersnake
T. e. vagrans - Wandering 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
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.

Conservation Status

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.


Organization
Status Listing
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Game DFG:SSC California Species of Special Concern
Bureau of Land Management BLM:S Sensitive
USDA Forest Service USFS:S Sensitive
Natureserve Global Conservation Status Ranks G3 S2 Vulnerable
World Conservation Union - IUCN Red List




IUCN:LC Least Concern

 


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