Northern Cottonmouth
Agkistrodon piscivorus
A stout, semi-aquatic pit viper of southeastern wetlands, named for the white lining of its mouth displayed as a threat.
- Venomous?
- Venomous
- Adult length
- 0.8-1.2 m (2.6-4 ft)
- Range
- Southeastern United States
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Overview
The Northern Cottonmouth is a heavy-bodied, semi-aquatic pit viper closely tied to wetlands, swamps, and slow-moving waterways of the southeastern United States. It is well known for its dramatic open-mouth threat display, revealing the white interior that gives it its common name.
Although often perceived as aggressive, it typically prefers to flee or display rather than bite when encountered.
How to identify it
- Heavy-bodied with dark olive, brown, or nearly black coloration, sometimes with faint banding visible up close
- Broad, blocky head distinct from the neck
- Heat-sensing pit between eye and nostril
- Vertically elliptical pupils
- Swims with its body riding high on the water's surface, unlike many harmless water snakes that swim mostly submerged
- White interior of mouth displayed when threatened
Habitat & range
Inhabits swamps, marshes, lake margins, sluggish rivers, and other wetland habitats across the southeastern United States, occasionally venturing into brackish coastal waters.
Behavior, diet & reproduction
Primarily nocturnal in warm weather, more diurnal in cooler seasons. Opportunistic feeder on fish, amphibians, small mammals, and carrion. Viviparous, bearing live young. Known for its gaping white-mouth threat display as a first line of defense before biting.
Frequently asked questions
Is the Northern Cottonmouth aggressive?
It is often defensive when cornered, displaying its white mouth as a warning, but generally prefers to retreat rather than attack.
How can I tell it from a water snake?
Cottonmouths swim with their bodies riding high on the water and have a blocky head with heat pits, unlike slimmer, submerged-swimming water snakes.
What does it eat?
It is an opportunistic feeder on fish, amphibians, small mammals, and carrion.
Where does it live?
It inhabits wetlands, swamps, and slow-moving waters across the southeastern United States.
Northern Cottonmouth guides
In-depth guides for identifying and understanding Northern Cottonmouth.
Northern Cottonmouth identified by the community
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