Western Aquatic Garter Snake

Western Aquatic Garter Snake

Thamnophis couchii

Silhouette: Alex Slavenko · PhyloPic

LCLeast ConcernNTVUENCR Endemic
Daily sighting probability ~30% · Possible
at Sequoia and Kings Canyon National Parks

In 3 days ~60% in a week ~90%

45 Verified sightings at Sequoia and Kings Canyon National Parks From 2019 to 2026
104 In all 2 parks
February Best month
☀️ Diurnal When it's spotted

About the Western Aquatic Garter Snake

Thamnophis couchii, commonly known as Couch's garter snake, the Sierra garter snake, or the western aquatic garter snake, is a highly aquatic species of snake in the family Colubridae. The species is endemic to the western United States, specifically the Sierra Nevada mountain range.

The specific name couchii is in honor of Darius Nash Couch, a U.S. Army officer and naturalist who collected specimens during the Mexican-American War and subsequent expeditions. The Sierra garter snake is a medium-sized, slender snake adapted for an aquatic lifestyle. They possess a somewhat pointed head, which aids in underwater foraging in fast-flowing currents. Like many garter snakes, they have a mild venom produced in the Duvernoy's gland that is harmless to humans but effective at subduing small, cold-blooded prey. Furthermore, because their diet frequently includes highly toxic newts, the snakes can sequester the tetrodotoxin in their own tissues, making them poisonous to potential predators like birds and mammals.

T. couchii is native to California with a small population in west-central Nevada and the Owens Valley. It is predominantly... Wikipedia →

Global Distribution

Parks Where Found

# Park Country Daily sighting probability
1 Sequoia and Kings Canyon National Parks 🇺🇸 United States
~30%
2 Yosemite National Park 🇺🇸 United States
~20%

Closest Relatives at Sequoia and Kings Canyon National Parks

Before you go

What are the chances of seeing a Western Aquatic Garter Snake in Sequoia and Kings Canyon National Parks?

Possible

About 30% of wildlife watchers report a Western Aquatic Garter Snake sighting in Sequoia and Kings Canyon National Parks on a given day, based on 45 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 8th most-seen of the 17 reptiles we can rate there. Over three days the chance rises to about 60%, and over a week to about 90%, if each day is a fresh chance.

When is the best time to see a Western Aquatic Garter Snake in Sequoia and Kings Canyon National Parks?

February–May and August

In those months about 30% of wildlife watchers report a Western Aquatic Garter Snake in Sequoia and Kings Canyon National Parks on a given day, against under 5% in October to January, the lowest months.

What time of day is best to see a Western Aquatic Garter Snake?

Between 1 and 4 pm

Across all the parks we cover, that three-hour window holds the most Western Aquatic Garter Snake sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.

Is Sequoia and Kings Canyon National Parks the best place to see a Western Aquatic Garter Snake?

Yes

Of the 2 parks where we can rate Western Aquatic Garter Snake sightings, Sequoia and Kings Canyon National Parks has the highest daily chance: about 30%. Next come Yosemite National Park (United States, about 20%).

Where does the Western Aquatic Garter Snake sighting chance come from?

GBIF citizen-science records

It is estimated from how often the Western Aquatic Garter Snake is recorded against all the reptiles logged in Sequoia and Kings Canyon National Parks (45 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.

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