‹ Compare two snakes
Northern Cottonmouth vs Banded Watersnake
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Melanie Gaddy, no rights reserved
Northern Cottonmouth
Agkistrodon piscivorus
Venomous(c) Alan Prather, some rights reserved (CC BY)
Banded Watersnake
Nerodia fasciata
Non-venomousThe quick way to tell
Check the face. The cottonmouth has a vertical pupil and a dark eye mask. The Banded Watersnake has round pupils and no mask.
Eyes ★ This settles it
Vertical slit pupil; heat-sensing pit between eye and nostril.
Round pupil, eyes set high on the head; no heat-sensing pit.
Head
Blocky, heavy brow, dark mask through each eye, pale snout.
Narrow head that flattens when alarmed; a dark stripe often runs from eye to jaw.
Pattern
Dark olive to nearly black, with faint wide bands clearest on young snakes.
Dark crossbands widest across the back; belly has dark square marks.
Pits
A deep heat-sensing pit on each side of the face, between the eye and the nostril.
None. There is no pit between the eye and the nostril.
Tail
Thick-based; young have a yellow tail tip.
Tapers evenly; no rattle.
What it does
Coils, vibrates its tail and gapes to show a white mouth lining.
Flattens its head and may strike if cornered; flees to water first.
Where it lives
Southeast from southeastern Virginia through the Carolinas, northern Georgia and Alabama, west to central Texas and Oklahoma, and up the Mississippi valley to southern Illinois, Missouri and southeastern Kansas.
Southeast coastal plain from North Carolina through Florida, west to eastern Texas and Oklahoma, and up the Mississippi valley to southern Illinois; introduced in California.