A Guide to the Amphibians
and Reptiles of California

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Identifying California Gartersnakes

Click here to see range maps for all California gartersnakes.

Click here to see a key to identifying California gartersnakes by counting scales.

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Not Dangerous
Gartersnakes do not have venom that is dangerous to most humans.

Determine if the snake is a Gartersnake


California gartersnakes are medium-sized slender snakes with a head barely wider than the neck and scales on the back which are keeled - having a ridge lengthwise on each scale.

Keeled Scales

Most species have a stripe on top of the back, and on the bottom of each side, but on some species this stripe is faint or absent, and sometimes the side stripes are absent. Many gartersnakes have red coloring on the sides, often with a red and black checkered pattern. Otherns have a variation of light and dark checkering on the sides.


Other striped snakes live in California which may resemble gartersnakes. If you are not certain that your snake is a gartersnake, check the striped California snakes page to determine what kind of snake it is.


Most California gartersnakes are active during the daytime, but sometimes they will be active at night during very hot weather. They are usually found in or around water, although sometimes they are found on land far from water. Exceptions are Marcy's Checkered Gartersnake which is most active at night, and the Northwestern Gartersnake which is not typically found near water.



Gartersnakes are found in a wide variety of natural habitats, from sea level to high elevations, including forests, grasslands, shrubland and chaparral, marshes, all types of ponds, lakes, streams and rivers, and even in rocky creeks in the desert. They are commonly found in grassy areas near water, laying on top of vegetation or along the banks of ponds, or in the still edges of streams. They may also be found in open areas or in woods away from water. They are absent from very dry areas or deserts except where there is water. Often they can be found hiding underneath objects such as boards, tarps, logs, rocks, and other debris, but just as often they will be seen crossing a trail or crawling away quickly through grass or into a pond or creek to escape.


When handled, gartersnakes will often release foul-smelling fluids from the vent near the end of the tail, and many will strike repeatedly at the handler. Gartersnakes do not pose any danger to humans, but their saliva does contain certain toxins which can cause redness and swelling at the site of a bite.

Determine the species of Gartersnake

Once you have determined that your snake is a gartersnake, look at the California gartersnake range maps to find out which species occur in your area. This will help to narrow down your choices.

California Gartersnakes are sometimes difficult to identify, because there are often several similar species inhabiting the same area. Adding to this difficulty is the fact that some species are highly variable in appearance, especially the Northwestern Gartersnake and the Coast Gartersnake. You may need to count certain scales in order to get a positive identification. If you have the snake in hand or have close-up photographs, especially of the head, look at our California gartersnakes key, which lists some scale counts that will help to identify a particular species.

Look at the pictures below and try to find the one that looks most like your snake. Keep in mind that there may be several species in your area which look similar, and that we do not depict variations of every species.

If you can get the snake in hand in order to look at its scales closely enough to count them, this scale count key can help determine the species more accurately.

All species of Gartersnakes in California are not dangerous to humans.

gartersnake gartersnake gartersnake
Santa Cruz Gartersnake
Thamnophis atratus atratus
Oregon Gartersnake
Thamnophis atratus hydrophilus                          
Diablo Range Gartersnake
Thamnophis atratus zaxanthus
gartersnake gartersnake gartersnake
Sierra Garter Snake
Thamnophis couchii
Two-striped Gartersnake
Thamnophis hammondii
Marcy's Checkered Gartersnake
Thamnophis marcianus marcianus
gartersnake gartersnake gartersnake
Mountain Gartersnake
Thamnophis elegans elegans
Wandering Gartersnake
Thamnophis elegans vagrans
gartersnake gartersnake gartersnake
gartersnake gartersnake gartersnake
gartersnake gartersnake  
  Coast Gartersnake
Thamnophis elegans terrestris
gartersnake gartersnake gartersnake
Valley Gartersnake
Thamnophis sirtalis fitchi

San Francisco Gartersnake
Thamnophis sirtalis
gartersnake gartersnake gartersnake
California Red-sided Gartersnake
Thamnophis sirtalis infernalis
Giant Gartersnake
Thamnophis gigas
gartersnake gartersnake gartersnake
  Northwestern Gartersnake
Thamnophis ordinoides

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