While all snakes are adept swimmers, some prefer water more than land. The species on the following list of water snakes in Illinois fall under the Genus Nerodia, more commonly referred to as water snakes. Water snakes are nonvenomous colubrid snakes that exhibit highly aquatic behavior. The Genus includes 9 total species, and all are native to North America.
Illinois has 57,918 square miles of land, but also 85 lakes and 87,110 miles of rivers within its borders. All of this water creates a great habitat for many types of aquatic wildlife, including reptiles like snakes. In particular, this makes many parts of the state a great home for water snakes.
Let’s take a look at which water snakes you can find in the state of Illinois!
The 6 Types of Water Snakes in Illinois
Illinois’ rich soil and expansive water systems make it home to water snakes like the green water snake, common water snake, diamondback water snake, yellowbelly water snake, copperbelly water snake, and the banded water snake.
1. Green Water Snake
Scientific name: Nerodia cyclopion
The green water snake, also sometimes called the Mississippi green water snake, can be found in the southernmost part of Illinois. They are not a highly populated snake in this area, but do still inhabit the far southwest portion of the state. This snake grows to be between 2 and a half feet to 3 and a half feet long and is mostly green or brown with dim black crossbars. Their belly features light spots on grey or brown. Females are typically larger than males and their scales are ridged.
This aquatic snake loves water, but is usually found basking on logs or brush. They commonly live in cypress swamps or rivers, which is why they’re mostly contained to the southern part of Illinois. They are mostly active during the day and feed in the evening on small reptiles, fish, and small animals.
2. Common Water Snake
Scientific name: Nerodia sipedon
The common water snake, also known as the northern water snake, is the most populated type of water snake and is very easy to find in Illinois. This snake is a light brown or gray color with red or dark brown cross-bands and splotches along its back or sides. On average, the common water snake is between two and three and a half feet.
This snake commonly is found basking on logs and rocks. They also commonly inhabit reservoirs in the limestone that lines all of the rivers’ shorelines. It’s clear to see why this snake enjoys almost all of Illinois, a state populated with water sources.
They are live-bearers, meaning that instead of laying eggs, they give birth to 10-15 live young in the late summer.
3. Diamondback Water Snake
Scientific name: Nerodia rhombifer
The diamondback water snake is predominantly brown, dark brown or dark olive green, with a black pattern along the back, each spot being diamond-shaped. Their scales are a very rough texture and they typically grow to be about 2 and a half to 3 and a half feet long. The underside is often a yellow or light brown color.
This snake is often confused for venomous copperheads, but is not poisonous. They are an aggressive snake though and will release musk and fecal matter if provoked.
They are commonly found all throughout Illinois, but especially in the southwest portion, along the many rivers. The diamondback water snake enjoys basking on tree limbs above the water and hunting for its prey which includes small amphibians, lizards, mice, etc.
4. Yellowbelly Water Snake
Scientific name: Nerodia erythrogaster flavigaster
The yellowbelly water snake is a type of plain-bellied water snake commonly found in Illinois and across the midwest. The yellowbelly water snake averages two and a half feet to four feet long and has a gray or green/grey back without markings. Their belly tends to be yellow with a touch of orange, hence their name.
This species prefers the quiet waters of swamps, sloughs, lakes, and ponds. They bask on logs in shallow water, on branches above the water, or along the shore. They are not venomous, but will strike or bike if threatened or cornered.
They feed off of fish, toads, frogs, tadpoles, salamanders, and crayfish, all of which are common alongside the Mississippi river that runs through Illinois. They are mostly contained to the southern region of the state.
5. Copperbelly Water Snake
Scientific name: Nerodia erythrogaster neglecta
Copperbelly water snakes are roughly the same size as the yellowbelly water snake, between two and a half and four feet, and have a dark colored or black back, and a red or orange-red belly. Like most other water snakes, they also have ridged scales.
The copperbelly water snake inhabits most parts of Illinois, as they live in river bottoms, swamps, marshes, and edges of ponds and lakes. They prefer forested floodplains and shrubby wetlands near shallow lakes and ponds especially, as well as slow moving rivers. In winter, they will hibernate in crayfish burrows, dense brush piles, and beaver lodges.
This snake is aquatic, but it may be seen basking on logs in water or along the shoreline. Like most water snakes, it is non-venomous, but they will release large amounts of nasty-smelling musk from glands at the base of the tail. Like other water snakes, their young are born alive in late summer. Like the yellowbelly snake, they are mostly found in the southern regions of the state.
6. Banded Water Snake
Scientific name: Nerodia fasciata
The banded water snake earns its name for its distinctive stripes and bands around its body. Adults are about two feet to almost four feet long. They are usually gray or brown in color, with dark cross-banding. Some are so dark in color that you can’t really see their patterns.
They are often mistaken for the venomous cottonmouth, but these snakes are non-venomous. They will attack if provoked, but will only bite or release a foul-smelling musk. They live in lakes, marshes, and streams and feed on fish and frogs and tend to bask alongside the streams they hunt in.
Banded water snakes are not very commonly found in Illinois, but have been spotted in the state, particularly in the southernmost parts.