Giant Garter Snake
Thamnophis gigas
California's largest garter snake, an endangered wetland specialist of the Central Valley.
- Venomous?
- Mildly venomous
- Adult length
- 0.9-1.6 m (3-5.2 ft)
- Range
- Central Valley of California
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Overview
The giant garter snake is the largest species in its genus and one of California's most threatened reptiles, having lost most of its historic wetland habitat to agricultural development.
It survives mainly in rice fields, irrigation canals, and remnant marshes throughout the Central Valley, where it depends on year-round water availability.
How to identify it
- Large, heavy-bodied garter snake
- Background color olive to brown with a yellowish dorsal stripe
- Lateral stripes present on rows three and four
- Checkered dark blotches between stripes in some individuals
- Keeled scales
- Distinguished from other California garter snakes chiefly by its larger size and heavier build
Habitat & range
Inhabits marshes, sloughs, ponds, and agricultural wetlands, especially rice fields and irrigation canals, throughout California's Central Valley. Requires slow-moving or standing water with emergent vegetation.
Behavior, diet & reproduction
Highly aquatic, foraging for fish and amphibians in wetlands and canals. Active by day in warmer months and less active during cooler periods. Bears live young in late summer. Considered a threatened species due to extensive wetland habitat loss.
Frequently asked questions
Why is the giant garter snake endangered?
Its wetland habitat throughout California's Central Valley has been extensively drained and converted to agriculture and development.
How big does it get?
It is the largest garter snake species, with adults commonly exceeding a meter in length.
Is it dangerous to people?
No, it is not dangerous to humans and its mild venom is used only on small prey.
Where does it live today?
It persists mainly in rice fields, canals, and remaining marshes across California's Central Valley.
Giant Garter Snake guides
In-depth guides for identifying and understanding Giant Garter Snake.
