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14 Species of Garter Snakes in California

Snakes are found all over the United States, and California is no exception. According to the California Department of Fish and Wildlife, the state is home to almost 50 different native snake species, including 4 species of garter snakes in California. These snakes are found in various habitats, including on and off the water.

14 Garter snakes in California

There are at least 4 different garter snake species in California with over 10 subspecies. While they may look scary, all the garter snakes in California are not harmful to humans.

These snakes do not produce venom that is dangerous to humans, and actually provide various benefits, such as acting as natural pest controllers, feeding on rodents and slugs. 

1. San Francisco garter snake

San francisco garter snake
San francisco garter snake | image by Brian Gratwicke via Flickr | CC BY 2.0

Scientific Name: Thamnophis sirtalis tetrataenia

The San Francisco garter snake is a member of the common garter snake family, and is found on the San Francisco peninsula. This species is a good swimmer that is mainly active during the day.

It is a medium-sized snake that can grow up to 55 inches long. This snake has a red head, a bluish green dorsal stripe bordered by black-colored stripes, and a bluish green belly.

2. California red-sided garter snake

California red sided garter snake
California red-sided garter snake | image by Don Loarie via Flickr | CC BY 2.0

Scientific Name: Thamnophis sirtalis infernalis

Another subspecies of the common garter snake, the California Red-Sided garter snake ranges from the state’s north coastal region to Humboldt County. It is found in a wide array of habitats, including woodlands, farmlands, grasslands, and forests. In most cases, the California Red-Sided garter snake is spotted near streams, ponds, and marshes.

3. Giant garter snake

Giant garter snake
Giant garter snake | image by Dave Feliz via Wikimedia Commons | CC BY-SA 3.0

Scientific Name: Thamnophis gigas

The Giant garter snake is currently found in the Glenn County area of California, as well as in northern Fresno County, Merced County, and the San Francisco Bay Delta. It thrives in wet areas, such as marshes, irrigation ditches, and drainage canals.

As its name suggests, this species is rather large and can grow up to 65 inches. It has a black, brown, or olive body, a yellow dorsal stripe, and a light-colored underside.

4. Northwestern garter snake

Northwestern garter snake
Northwestern garter snake | image by Corvi Zeman via iNaturalist | CC BY 4.0

Scientific Name: Thamnophis ordinoides

The northwestern garter snake is not widespread throughout the state of California, and is actually only found in the south to northern portion of Humboldt County in California. This small snake averages between 12 and 24 inches long and comes in a wide array of patterned colors.

5. Valley garter snake

Valley garter snake
Valley garter snake | image by LassenNPS via Wikimedia Commons | CC BY 2.0

Scientific Name: Thamnophis sirtalis fitchi

The Valley garter snake is a subspecies of the common garter snake, which is one of the largest distributed species of garter snake throughout North America. In California, the Valley garter snake is found all throughout the northern part of the state.

This species can grow up to 55 inches long, though the average length is under 36 inches. An interesting fact about the Valley garter snake is that they consume the toxic Pacific Newts, which are deadly to most other predators.

6. Coast garter snake

Coast garter snake
Coast garter snake | image by Folini via Wikimedia Commons | CC BY-SA 3.0

Scientific Name: Thamnophis elegans terrestris

A subspecies of the Western terrestrial garter snake, the Coast garter snake is found throughout California’s coast. Despite its name, this snake is more terrestrial than aquatic but still likes to be near a water source.

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It can measure 18 to 43 inches long, and its body can be a wide array of colors. However, this snake typically has a yellowish stripe running along the bottom part of its sides, as well as a yellow dorsal stripe.

7. Wandering garter snake

Wandering garter snake hissing
Wandering garter snake hissing | image by USFWS Mountain-Prairie via Flickr | CC BY 2.0

Scientific Name: Thamnophis elegans vagrans

In the state of California, the wandering garter snake is only found in the southern part of the Sierra Nevada Mountains. This is a subspecies of the Western terrestrial garter snake and can measure up to 43 inches long. Its body is brown, green, or gray with lighter-colored lateral stripes.

8. Mountain garter snake

Mountain garter snake
Mountain garter snake | image by Velo Steve via Wikimedia Commons | CC BY-SA 2.0

Scientific Name: Thamnophis elegans elegans

The mountain garter snake is found in the Sierra Nevada Mountains, as well as throughout the majority of the northern part of California. It can grow up to 43 inches long and has a black or deep olive-brown body.

This mountain garter snake can be easily identified by the three stripes on its sides and back. These stripes can be orange, white, or yellow.

9. Two-striped garter snake

Two-striped garter snake
Two-striped garter snake | image by USFWS Pacific Southwest Region via Flickr | CC BY 2.0

Scientific Name: Thamnophis hammondii

The two-striped garter snake is found in Monterey County, along the coast ranges of southern California, and even down into the northern parts of Baja California. The two-striped garter snake is most commonly found close to a water source, and can even be seen near pools. They have an average length of 18 to 30 inches long and are adorned with a yellow or grayish stripe running down each side of their body.

10. Marcy’s checkered garter snake

Marcy’s checkered garter snake
Marcy’s checkered garter snake | image by swbirder via iNaturalist | CC BY 4.0

Scientific Name: Thamnophis marcianus marcianus

Marcy’s checkered garter snake is a subspecies of the checkered garter snake, and is only found in the southeastern portions of the state. In fact, this snake typically stays in Riverside and Imperial counties.

It measures between 13 and 42 inches long and has a yellowish brown, deep brown, or tan body with black blotches on its sides that alternate, which gives it a checkered board pattern.

11. Sierra garter snake

Sierra garter snake
Sierra garter snake | image by Cataloging Nature via Flickr | CC BY 2.0

Scientific Name: Thamnophis couchii

The Sierra garter snake is found in large mountain rivers, ponds, creeks, and lakes, and prefers areas that have an abundance of vegetation, rocks, and a water source. In California, this species sticks to the Sacramento rivers and the Sierra Nevada Mountains. It can grow up to 38 inches long and can has a dark brown, black, or dark olive body.

12. Santa Cruz garter snake

Santa Cruz garter snake
Santa Cruz garter snake | image by Edward Rooks via Flickr | CC BY-SA 2.0

Scientific Name: Thamnophis atratus atratus

The Santa Cruz garter snake is found throughout the state of California and is a subspecies of the aquatic garter snake. This aquatic snake spends most of its time in or near the water and can remain underwater for long periods of time.

They are slender and reach lengths of up to 40 inches long. They have a black, gray, or brown body with dorsal stripes in shades of orange and yellow.

13. Diablo range garter snake

Diablo range garter snake
Diablo range garter snake | image by Greg Schechter via Flickr | CC BY 2.0

Scientific Name: Thamnophis atratus zaxanthus

The Diablo range garter snake is another subspecies of the aquatic garter snake and can be found from Napa to the East Bay, and even in the southern portion of the Santa Cruz Mountains. Like other aquatic garter snakes, this subspecies thrives in water, where it spends most of its time. It has an average length of 18 to 28 inches long, but can grow up to 40 inches long.

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14. Oregon garter snake

Oregon garter snake
Oregon garter snake | image by garth_harwood via iNaturalist | CC BY 4.0

Scientific Name: Thamnophis atratus hydrophilus

This subspecies of the aquatic garter snake is found in the northern Sonoma County range of California and has a long slender body with a head that is not much wider than its neck. They typically reach lengths of about 28 inches, with an average of 20 to 21 scales at their mid-body. They have an olive gray to brownish color and some can even have a light stripe running along their sides and down their back.