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What is a Western Terrestrial Garter Snake (Thamnophis elegans)

Western Terrestrial Garter Snake (Thamnophis elegans)

Western Terrestrial Garter Snake Overview

The Western Terrestrial Garter Snake is a mildly venomous snake that is found in the western United States and Canada. Their venom is effective at attacking and destroying muscle tissue in very small prey items like mice and rodents but it lacks the potency to have any real damaging effects on humans. When they have bitten people, symptoms include localized edema or swelling, and pain at the bite site but the symptoms quickly subside on their own bearing a unique allergic reaction.

While preferring to stay on land, as the terrestrial part of its name would imply, these snakes have been found hanging out around wetlands and streams of the Sierra Nevada mountains. Even though it’s not necessarily a constrictor snake, the Western Terrestrial Garter Snake has been seen squeezing its prey, albeit sloppily or inefficiently. A North American snake that IS good at using constriction as a hunting method would be the Gopher Snake or the Rosy Boa which we have written about.

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What is a Western Terrestrial Garter Snake


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Size and Body Description

Western Terrestrial Garter Snakes are medium-sized snakes with a head that is barely larger than its neck and will have around 10 lower labial scales and 8 upper labial scales. The reason why this is important to know is that different garter snakes will have a different amounts of labial scales so if you need help identifying a species, this is a method you can use to help narrow it down. 

Starting at the top of the neck, a yellow stripe is usually present that runs the entire length of the body ending at the tail. The same yellow or yellowish stripe can also be seen on either side of its body as well. Between these stripes, you will find spots that are black or even red in color.

There isn’t one set base color of the garter snake as they can be red, brown, olive, or grayish green which can lead to some issues identifying which species you are looking at. To further prove this, there have been accounts of all-black Western Terrestrial Garter Snakes which adds to the complications.


Western Terrestrial Garter Snakes will grow to be around 18 to 43 inches in length.

Western Terrestrial Garter Snake

Western Terrestrial Garter Snake eating a vole


Western Terrestrial Garter Snakes seem to be opportunistic feeders eating a wide range of prey including mice, fish, frogs, tadpoles, and even small birds and lizards if they can catch them. These snakes are also known to eat slugs, snails, worms, insects, and even carrion, which are just dead animals.


Western Terrestrial Garter Snakes will begin mating in the spring with live young being born anywhere from July to September. Female snakes will give birth to around 4 to 19 snakes at a time depending on where the snake lives.


Western Terrestrial Garter Snakes are found predominantly on the western side of the United States and can also be found in parts of Canada. In the United States, these snakes can be found in Washington, Oregon, California, Idaho, Nevada, Montana, Wyoming, Colorado, Utah, Arizona, and New Mexico.

In Canada, Western Terrestrial Garter Snakes have been seen in the southern regions of Alberta, Saskatchewan, and British Columbia.

Where Found

Western Terrestrial Garter Snakes can be found in a wide range of places including grasslands, shrublands, woodlands, and in mountains. They can also be spotted near wetlands, streams, and ponds.


As of writing this, the Western Terrestrial Garter Snakes is not federally protected as their populations are considered to be stable.

References Used

Western Terrestrial Garter Snake (Thamnophis elegans)