Western terrestrial garter snake
A slim, striped snake found from stream banks to talus slopes across ten of these parks, and the most commonly seen reptile in several of them.
Western terrestrial garter snake at a glance
Thamnophis elegans tham-NOH-fiss EL-eh-gunz
- Type
- Reptile · snakes
- Diet
- Carnivore
- Size
- Adults typically run 16 to 43 inches long, roughly the length of a baseball bat.
- Lifespan
- Around 6 to 12 years in the wild.
- Conservation
- Least concern
Eats earthworms, insects, small amphibians, fish, rodents
It tracks prey by flicking its tongue to pick up scent, then swallows small, slow animals like worms, frogs, and fish whole, alive.
Should you worry?
Essentially harmless. It has mild venom in its saliva meant for small prey, and a bite on a person causes at most brief redness or swelling — nothing serious. If handled, it will usually just release a foul-smelling musk from beneath its tail, which, not any bite, is the real reason to watch instead of picking one up.
At Fossil Butte, rangers count exactly two reptile species in the entire monument, and this is one of them — a slim, striped snake sliding out from under a sagebrush root before you’ve finished raising a camera. Lower down, along the creek, it hunts the wet edges of streams and ponds; climb toward the rimrock and the same species turns up again on the talus slopes, hunting a completely different neighborhood.
Pick one up anyway and it won’t waste time on a bite. It empties its cloaca and musk glands at once and smears the whole foul-smelling mess over itself and your hands, betting that whatever grabbed it will let go just to get the smell off. It usually works. The snake does carry venom, delivered through grooved teeth at the back of its jaw rather than fangs in front, but it’s built for holding down a worm or a half-swallowed frog, not for a person — a bite leaves redness for a day, nothing more.
It is, in park after park in this batch, the reptile you’re most likely to actually see: common at Glacier, at Rocky Mountain, at Yellowstone, everywhere the ground has both water nearby and rock to hide in. Wash your hands if you’ve held one, and go check the next patch of streamside grass — it’s probably already watching you from there.
Did you know?
- Cornered, a western terrestrial garter snake will empty its musk glands and smear the smelly mixture over itself and its attacker rather than rely on biting.
- At Glacier National Park, it's one of only three confirmed reptile species and is sometimes called the "wandering" garter snake.
- Its venom comes from grooved teeth at the back of its jaw, not fangs, and is only strong enough to trouble small prey like worms and frogs — a bite on a person causes little more than mild redness.
Common questions
Are western terrestrial garter snakes venomous? Should I worry if one bites?
They have mild venom made for subduing small prey, delivered through grooved teeth instead of fangs. A bite on a person causes at most brief redness or swelling — wash it and move on; no antivenom or emergency care is needed.
Why does a garter snake smell so bad when you pick it up?
It releases musk and waste from glands near its tail and smears it over itself and your hands, a defense meant to make you let go, not a sign it's sick.
Where do you find garter snakes in these parks?
Along stream and pond edges at lower elevations, and on rocky talus slopes higher up — it's one of the most commonly seen reptiles across this batch of ten parks.
What do garter snakes eat?
Small, slow prey: earthworms, insects, frogs, small fish, and occasionally young rodents, swallowed whole.
What eats a western terrestrial garter snake?
Many birds, including hawks, harriers, ospreys, bald eagles, herons, sandhill cranes, gulls, crows, and even American robins, plus mammals. When grabbed, it smears a foul-smelling musk on itself and its attacker.