Reptiles
Green Water Snake
Nerodia cyclopion · also called green water snakes
Along a shaded bayou, several large green water snakes bask together on a fallen branch, their sheer size and dark colouration enough to make most passersby assume they’ve stumbled onto a group of venomous cottonmouths instead.
Overview
The green water snake, Nerodia cyclopion, is a large, non-venomous water snake native to swamps and bayous across the south-central United States. Its considerable size and defensive display, so often mistaken for the venomous cottonmouth it shares habitat with, make it one of the more frequently misidentified snakes in the American South.
Harmless, but built to look otherwise
Despite carrying no venom at all, the green water snake’s imposing size and readiness to hiss and strike when cornered give it a reputation it doesn’t entirely deserve, a defensive bluff that works a little too well on people.
Status
Least Concern — widespread and stable across suitable swamp and bayou habitat throughout the south-central United States.
Green Water Snake: common questions
Is the green water snake venomous?
No, the green water snake is entirely non-venomous, though its large size, dark olive-green colouration, and defensive hissing and striking display when cornered frequently lead people to mistake it for the venomous cottonmouth, a case of mistaken identity that unfortunately sometimes leads to the harmless snake being killed unnecessarily.
Why do green water snakes bask together in groups?
Green water snakes are often found basking together in considerable numbers on branches, banks, or floating vegetation, a social basking habit shared with several other water snake species that likely reflects the limited availability of good basking sites rather than any particularly social behaviour between individuals.
How big does a green water snake get?
The green water snake is a large, heavy-bodied species, ranking among the bigger water snakes found within its south-central United States range, a substantial size that contributes to its frequent confusion with the venomous cottonmouth despite being entirely harmless.
Where does the green water snake live?
The green water snake is native to swamps, bayous, and sluggish waterways across the south-central United States, particularly within the Mississippi River drainage, generally favouring slow-moving or still water with abundant vegetation.