- 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. 
Click on the language to view common names.
Common Names in English:
Two-striped Gartersnake, Two-striped Garter Snake
Common Names in French:
Serpent-jarretiere ? Deux Raies
Common Names in German:
Common Names in Spanish:
The family Colubridae, which includes the kingsnakes (Lampropeltis spp. ), is the largest, most widespread, and diverse family of snakes , with few physical characteristics universal among all species. The family contains 70 percent of the known species of snakes, with more than 1700 species worldwide (Pough et al. 1998). Although some colubrids are dangerously venomous , most are harmless to humans. 
Species Thamnophis hammondii
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.
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).
This species is considered one of the most aquatic
of garter snakes
and is typically associated with wetland habitats
such as streams
(Fitch, 1940; Rossman, et al.
1996). It is closely
associated with streams with rocky beds
by willows (Stebbins,
1985); also ponds
, wetlands and vernal
pools. It also occurs
in mixed oak, oak woodlands and chaparral
on coastal slopes
and foothills to sea
Generally found around pools, creeks, cattle tanks , and other water sources, often in rocky areas, in oak woodland, chaparral, brushland , and coniferous forest .
Typically found in a lake at a mean distance from sea level of 317 meters (1,039 feet).
This highly aquatic
is generally found in or
near permanent fresh water
, often along streams
with rocky beds
by willows and other riparian
vegetation, including mountain slopes
and desert oases (Jennings and Hayes 1994, Rossman et al.
1996, Grismer 2002, Stebbins 2003). In the southern part of its range
it is restricted
to palm oases..
List of Habitats :
- 1 Forest
- 1.4 Forest - Temperate
- 5 Wetlands (inland)
- 5.1 Wetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls )
- 5.2 Wetlands (inland) - Seasonal/Intermittent/Irregular Rivers/Streams/Creeks
- 5.3 Wetlands (inland) - Shrub Dominated Wetlands
- 5.4 Wetlands (inland) - Bogs , Marshes, Swamps , Fens , Peatlands
- 5.9 Wetlands (inland) - Freshwater Springs and Oases [more info]
Presumably, T. hammondii forages
underwater, but no data
behavior are available (Rossman, et al.
, toads, small anurans and fish, fish eggs, and earthworms
(Fitch, 1940; Stebbins, 1985; Van Denburgh and Slevin, 1918).
Eats tadpoles, newt larvae, small frogs and toads, fish, and occasionally worms and fish eggs. Probably forages for food in and under water. 
Much discussion has occurred regarding intergrading species of Thamnophis (Fitch, 1940, 1948; Rossman, 1979; Rossman and Stewart, 1987), though T. hammondii appears to be the lone taxon in western Riverside County. Courtship begins in Late March and early April (Cunningham, 1955). Clutch size ranges from 3 to 36, with an average of 15.6 in seven litters (Rossman, et al. , 1996). Stebbins (1985) noted that a captive animal gave birth to 25 young. Neonates are born in late July and August. Stewart (1972) reported that a female isolated from males for 53 months produced a living neonate, which suggests a type of sperm storage mechanism as can be found in some other species of snakes (e.g. , red-diamond rattlesnake).
. 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
Annual activity range is between January and November. During hot weather, T. hammondii may be crepuscular or nocturnal (Klauber, 1924).
- Whittaker & Margulis,1978
- C. Linnaeus, 1758
- (Hatschek, 1888) Cavalier-Smith, 1983
- Grobben, 1908
- (Haeckel, 1874) Cavalier-Smith, 1998
- Bateson, 1885
- Cuvier, 1812
- Jawed Vertebrates
- Goodrich, 1930
- Superorder: Lepidosauria () -
- Infraclass: Lepidosauromorpha ()
- Subclass: Diapsida ()
- Class: Lepidosauria ()
- Superclass: Tetrapoda () - Goodrich, 1930
- Infraphylum: Gnathostomata () - auct. - Jawed Vertebrates
- Subphylum: Vertebrata () - Cuvier, 1812 - Vertebrates
- Phylum: Chordata () - Bateson, 1885 - Chordates
- Infrakingdom: Chordonia () - (Haeckel, 1874) Cavalier-Smith, 1998
- Branch: Deuterostomia () - Grobben, 1908
- Subkingdom: Bilateria () - (Hatschek, 1888) Cavalier-Smith, 1983
- Kingdom: Animalia () - C. Linnaeus, 1758 - animals
Thamnophis couchii hammondi Beltz 2003 • Thamnophis digueti Mocquard 1899 (Fide Mcguire and Grismer 1993) • Thamnophis elegans hammondii • Thamnophis hammondii digueti Stebbins 1985: 207 • Thamnophis hammondii — Liner 1994 • Thamnophis hammondii — Stebbins 1985: 207
Status: Accepted Name
Comment: Named after William Alexander Hammond (1828-1900), American physician. Reproduction : ovoviviparous.
Formerly included in Thamnophis couchii. Includes T. digueti Mocquuard, 1899 of Baja California. The specific name in IUCN Red Lists prior to 2007 was incorrectly spelt as hammondi. (Ref. 310561).
The taxonomy of North American Pacific coast garter snakes (Thamnophis)
has long been studied, debated and revised, leaving a convoluted
trail of name changes, subdivisions and regroupings throughout the
literature. Thamnophis hammondii was originally described
by Kennicott in 1860. Since then, numerous scientists such as Cope
(1900), Ruthven (1908), Van Denburgh and Slevin (1918), Fitch (1940,
1948), Fox (1948, 1951), Lawson and Dessauer (1979), Rossman (1979),
Rossman and Stewart (1987), and McGuire and Grismer (1993) have vigorously
presented their conclusions regarding the systematic relationship
of the various species under the genus Thamnophis.
Fitch (1940) conducted an extensive study of this group and suggested that T. ordinoides, T. hammondii, and T. digueti (the three species recognized at that time) formed a group that he termed ordinoides artenkreis. Later, Fitch (1948) relegated T. hammondii to a subspecies of T. ordinoides, creating T. o. hammondii and leaving T. digueti as a full species. After further taxonomic revisions over the next 40 years, the species recognition included T. ordinoides, T. elegans, T. couchii, T. gigas, T. atratus, and T. hammondii; leaving T. digueti out of consideration, suggesting that it is excluded from the T. couchii complex (which includes the later four species listed).
The most recent study (Mcguire and Grismer, 1993) addressed the relationship of T. hammondii and T. digueti, concluding that they should be placed in the synonymy of T. hammondii of Kennicott (1860). They suggested that the observed variation in scale counts was random, resulting from isolation of various populations in Baja California. They hypothesize that the xerification of the Baja peninsula caused fragmentation of the previously continuous distribution of T. hammondii in Baja, possibly extending as far south as the ismuths of La Paz. Variation in color pattern and squamation, they suggest, occurred after this fragmentation.
Members of the genus Thamnophis
ZipcodeZoo has pages for 68 species and subspecies in this genus:
T. angustirostris (Longnose Garter Snake) · T. atratus (Aquatic Gartersnake) · T. atratus atratus (Santa Cruz Garter Snake) · T. atratus hydrophilus (Aquatic Garter Snake) · T. brachystoma (Short-Headed Garter Snake) · T. butleri (Butler's Gartersnake) · T. chrysocephalus (Goldenhead Garter Snake) · T. couchii (Couch's Garter Snake) · T. couchii couchii (Western Aquatic Garter Snake) · T. cyrtopsis (Black-Necked Garter Snake) · T. cyrtopsis collaris (Black-Necked Garter Snake) · T. cyrtopsis ocellatus (Black-Headed Garter Snake) · T. elegans (Terrestrial Gartersnake) · T. elegans arizonae (Arizona Garter Snake) · T. elegans elegans (Mountain Garter Snake) · T. elegans terrestris (Coast Garter Snake) · T. elegans vagrans (Wandering Garter Snake) · T. elegans vascotanneri (Upper Basin Garter Snake) · T. eques (Mexican Gartersnake) · T. eques eques (Mexican Garter Snake) · T. eques megalops (Mexican Garter Snake) · T. exsul (Montane Garter Snake) · T. fulvus (Highland Garter Snake) · T. gigas (Giant Gartersnake) · T. godmani (Godman's Garter Snake) · T. hammondi (Two-Striped Garter Snake) · T. hammondii (Two-Striped Gartersnake) · T. marcianus (Checkered Garter Snake) · T. melanogaster (Blackbelly Garter Snake) · T. melanogaster melanogaster (Blackbelly Garter Snake) · T. mendax (Tamaulipan Montane Garter Snake) · T. ordinoides (Northwestern Gartersnake) · T. ordinoides ordinoides (Northwestern Garter Snake) · T. proximus (Western Ribbon Snake) · T. proximus diabolicus (Arid Land Ribbon Snake) · T. proximus orarius (Gulf Coast Ribbon Snake) · T. proximus (Western Ribbon Snake) · T. proximus rubrilineatus (Redstripe Ribbon Snake) · T. radix (Plains Gartersnake) · T. radix haydeni (Plains Garter Snake) · T. radix haydenii (Western Plains Garter Snake) · T. radix radix (Eastern Plains Garter Snake) · T. rossmani (Rossman's Garter Snake) · T. rufipunctatus (Narrow-Headed Garter Snake) · T. rufipunctatus rufipunctatus (Narrowhead Garter Snake) · T. sauritus (Eastern Ribbonsnake) · T. sauritus nitae (Blue-Striped Ribbon Snake) · T. sauritus sackenii (Eastern Ribbon Snake) · T. sauritus sauritus (Eastern Ribbon Snake) · T. sauritus septentrionalis (Eastern Ribbon Snake) · T. scalaris (Longtail Alpine Garter Snake) · T. scaliger (Short-Tail Alpine Garter Snake) · T. sirtalis (San Francisco Garter Snake) · T. sirtalis annectens (Common Garter Snake) · T. sirtalis concinnus (Common Garter Snake) · T. sirtalis dorsalis (Common Garter Snake) · T. sirtalis fitchi (Common Garter Snake) · T. sirtalis infernalis (California Red-Sided Garter Snake) · T. sirtalis pallidulus (Common Garter Snake) · T. sirtalis parietalis (Common Garter Snake) · T. sirtalis pickeringii (Common Garter Snake) · T. sirtalis semifasciatus (Chicago Garter Snake) · T. sirtalis similis (Blue-Striped Garter Snake) · T. sirtalis sirtalis (Common Garter Snake) · T. sirtalis tetrataenia (Common Garter Snake) · T. sumichrasti (Sumichrast's Garter Snake) · T. valida (West Coast Garter Snake) · T. valida valida (West Coast Garter Snake)
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Accessed through GBIF Data Portal February 27, 2008:
- California Academy of Sciences: CAS Herpetology Collection Catalog
- Museum of Vertebrate Zoology: Terrestrial vertebrate specimens
- Santa Barbara Museum of Natural History: Santa Barbara Musem of Natural History
- Biodiversity Heritage Library NamebankID: 2545653
- Catalogue of Life Accepted Name Code: Rep-7147
- Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 209149
- IUCN ID: 246005
- Natural Heritage Network Species Identifier: ARADB36160
- Zipcode Zoo Species Identifier: 17661
- Nafis, Gary. California Reptiles and Amphibians [back]
- Painter, Charles W., Chuck L. Hayes, and James N. Stuart "Recovery and Conservation of the Gray-Banded Kingsnake. New Mexico Department of Game and Fish. May 1, 2002. [back]
- Standard Deviation = 449.950 based on 57 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
- Frost, D.R., Hammerson, G.A. & Hollingsworth, B. 2007. Thamnophis hammondii. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 05 February 2012. [back]