San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
Hammond Two-striped Gartersnake, photographed by Brad Holliingsworth, 2001

Thamnophis hammondii
Two-striped Gartersnake

COLUBRIDAE

Thamnophis comes from the Greek Thamn, meaning shrub and ophis meaning snake. Since Gartersnakes live in water, this name does not appear to be well-choosen (the Shrub Snake?).

Description

This snake may reach a length of three feet, though 18 inches to two feet is more usual. Its body proportions are unremarkable; it is neither slender nor stout. Its scales are keeled, with a low ridge down the center of each, which breaks up the reflection of light and results in a dull luster.

Other than its rapidly extended red tongue, this species of Gartersnake is fairly drab in color. Its overall color is olive drab, and it is accented low on each side by a yellow stripe. It lacks the dorsal stripe typical of other Gartersnakes. Patterned into the dorsal coloration are four rows of small, dark, somewhat inconspicuous spots. The belly is dull yellow and may grade into orange or reddish coloration.

Range and Habitat

The Two-striped Gartersnake is distributed from central California as far south as the La Presa region in Baja California. In southern California, it is cismontane, found from the coast to the foothills and mountains.

This is probably the most common snake in southern California, and it is not unusual to see several individuals at a time in a given spot. Though not exclusively aquatic, Gartersnakes are most frequently encountered in or near water, inhabiting streams, ponds, and lakes throughout their range. They can often be found even in temporary bodies of water such as vernal pools.

Natural History

When captured, the Gartersnake displays a feisty disposition, writhing, flattening its head, striking, and biting. Added to these alarming traits is its habit of exuding a foul-smelling excrement from its cloaca. The smell persists on its captor's hands and clothes for some time after exposure.

Being mostly aquatic, the Gartersnake's food consists mostly of what is available in or near water. This includes small fish, tadpoles, frogs, toads, and insect larvae. In turn, the snakes may be preyed upon by raptors and various carnivorous mammals, including coyotes and raccoons.

Gartersnakes are ovoviviparous -- bearing their young alive. Up to 25 may be born at a time, though half that many is more usual. Breeding begins in April and May and continues through the summer. Gestation is about nine weeks.

Conservation Status

The Two-striped Gartersnake is currently a Federal Special Concern species (FSC) and protected as a California Special Concern species (DFG-CSC). Because of widespread negative attitudes towards snakes, very few conservation programs, worldwide, have been created. A much higher percentage of snakes are threatened with extinction than is currently recognized. Therefore, snakes are particularly suspectible to being overlooked by conservation-minded biologists.


Text contributed by Dick Schwenkmeyer.
Photograph by Bradford Hollingsworth.

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