(Photographed at Snake Road, October, 2023)

Mississippi Green Watersnake

Scientific Name: Nerodia cyclopion

Average Length: 30–42 inches (76–107 cm)

Maximum Length: About 55 inches (140 cm)

Status at Snake Road: Uncommon

Venomous? No

Description

The Mississippi Green Watersnake is one of the most distinctive aquatic snakes found at Snake Road, though its appearance can be surprisingly variable. Most adults are olive-green, olive-brown, or grayish-green with a pattern that becomes faint or nearly invisible as they age. Younger individuals often display darker crossbands that gradually fade over time.

Like other watersnakes, it has strongly keeled scales that give it a rough appearance. One of its most recognizable features is its large eyes, which are positioned noticeably high on the head, allowing the snake to keep much of its body submerged while watching for prey. Dark vertical bars along the upper and lower lips are usually visible, even in older adults.

Adults are heavy-bodied snakes but are generally a bit more slender than similarly sized Diamond-backed Watersnakes.

Behavior

Mississippi Green Watersnakes are highly aquatic and spend much of their lives in swamps, sloughs, flooded timber, and quiet backwaters. They are excellent swimmers and often remain nearly motionless with only their eyes and nostrils above the surface while searching for prey.

When approached, they usually slip quietly into the water rather than standing their ground. If captured, however, they can become defensive, striking repeatedly and releasing a foul-smelling musk.

Their diet consists primarily of fish and amphibians, though they will occasionally consume crayfish and other aquatic animals.

Habitat

At Snake Road, Mississippi Green Watersnakes are most closely associated with the swamp and flooded bottomlands west of the road. They favor areas with slow-moving or still water, abundant aquatic vegetation, and submerged logs or branches for cover. During migration, they cross Snake Road while moving between these wetlands and upland overwintering sites in the nearby limestone bluffs.

Where You're Most Likely to See One

Your best chance of finding a Mississippi Green Watersnake is along the western edge of Snake Road near the swamp, drainage ditches, and flooded woods. They are most often encountered basking near the water's edge or slowly moving through shallow water during warm afternoons.

Commonly Confused With

Diamond-backed Watersnake (Nerodia rhombifer)

These two species frequently occur together and can appear very similar, especially as adults. Diamond-backed Watersnakes usually retain a more obvious diamond or chain-like pattern and have a stockier build. Mississippi Green Watersnakes tend to be more uniformly olive or greenish with their markings fading considerably with age. Their large, high-set eyes and barred lips are also useful field marks.

Plain-bellied Watersnake (Nerodia erythrogaster)

Older Plain-bellied Watersnakes are often nearly patternless, much like adult Mississippi Greens. The easiest way to distinguish them is by looking at the belly if it is visible. Plain-bellied Watersnakes have a mostly unmarked yellow, cream, or orange belly, while Mississippi Green Watersnakes typically have dark markings or mottling on the underside. Mississippi Greens also have noticeably larger eyes set higher on the head.

Common Watersnake (Nerodia sipedon)

Juvenile Mississippi Green Watersnakes can resemble Common Watersnakes because both have dark crossbands early in life. Common Watersnakes usually keep a bolder banded or blotched pattern into adulthood, whereas Mississippi Green Watersnakes often become much more uniformly colored as they mature.

Fun Fact

The Mississippi Green Watersnake reaches the northern edge of its range in southern Illinois, making Snake Road one of the best places in the Midwest to observe this species. While it is widespread farther south, relatively few locations offer visitors such reliable opportunities to see it in the wild.

Related Products

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