Cottonmouth Confusion

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Published on: Jun. 2, 2004

Last revision: Nov. 16, 2010

Cottonmouth snake in defensive posture

and along the state's big rivers. In early summer and fall you may see them basking on rocks and logs, but during the heat of July, August and September they are mostly nocturnal.

This snake differs from cottonmouths by having a series of dark brown blotches along its back that are connected in a chain-like pattern.

Yellow-Bellied Water Snake

(Nerodia erythrogaster)

As an adult, this medium-size, non-venomous snake ranges from 30 to 48 inches long. Like the diamond backed water snake, it inhabits the still waters of swamps, ponds and oxbow lakes. It does not live in the Ozarks, either. In eastern Missouri, it ranges from the Bootheel in the south as far north as Pike County, just above St. Louis. It can also be found in roughly the western third of the state.

Adults of this species can be identified by their gray to greenish gray or brownish black color. The adults lack any distinct pattern along their backs. The belly of the snake is yellow with no markings.

Broad-Banded Water Snake

(Nerodia fasciata)

In Missouri, this species is restricted to lowland swamps and oxbow lakes of the Bootheel. Adults average from 22 to 36 inches long. Non-venomous broad banded water snakes are easily identified by wide brown or black bands separated by a cream yellow color.

Graham's Crayfish Snake

(Regina grahamii)

This snake is found statewide except in the Ozarks. Adults range from 18 to 28 inches long. These non-venomous snakes are very secretive. They eat mainly softbodied crayfish and prefer still or barely moving water, such as ponds, slow streams and marshes.

Many are killed simply because they are found near the water and believed to be cottonmouths, but these inoffensive creatures are reluctant to bite even when handled.

Unlike cottonmouths, this snake is brown with a yellowish stripe along its side. A faint tan stripe may be present along its back. Its belly is cream colored and has a very faint row of gray dots down the midline.

Other Semi-Aquatic Snakes

Though usually not mistaken for cottonmouths, there are two other semi-aquatic, non-venomous snakes found in Missouri: the Mississippi green water snake (Nerodia cyclopion) and the western mud snake (Farancia abacura).

The Mississippi green water snake is indigenous to southeast Missouri. It is not often seen, let alone mistaken for a cottonmouth. In fact, the snake hasn't been seen in Missouri since 1994 and is listed

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