10 Types of Water Snakes Found in Illinois! (ID Guide)
“What kinds of water snakes can you find in Illinois?“
Is it just me, or do you also find water snakes fascinating? There’s something about the way they move across the water that is incredibly interesting. Whenever I am near a pond, marsh, or other body of water, I make sure to look for any water snakes moving about.
Today, you are going to learn about 10 water snakes that live in Illinois.
The species below are considered either aquatic or semi-aquatic, which means that it’s very likely that you will see them actively swimming or extremely close to water, such as sunning themselves on a bank.
#1. Common Water Snake
- Nerodia sipedon
There are two subspecies of the Common Water Snake in Illinois.
Their coloration varies depending on which one you see!
-
Northern Water Snake (N. s. sipedon):
- Coloration is pale grey to dark brown with reddish-brown to black bands.
- Large adults become darker with age and appear almost plain black or dark brown.
-
Midland Water Snake (N. s. pleuralis):
- Typically light gray in color, but some individuals are reddish.
- Near the head, they have dark crossbands. As you move down the snake, the crossbands are replaced by dark squarish blotches.
This species is the most common watersnake in Illinois!
Common Water Snakes prefer slow-moving or standing water such as ponds, lakes, vernal pools, marshes, and slow-moving rivers and streams. They’re most often seen basking on rocks or logs in or near the water.
Common Water Snake Range Map
Credit: Virginia Herpetological Society
When disturbed, Common Watersnakes flee into the water to escape. However, if grabbed or captured, they’re quick to defend themselves. They will release a foul-smelling musk from glands near the base of their tale, flatten their body, and strike the attacker.
While non-venomous, they can deliver a painful bite!
Their saliva contains a mild anticoagulant that can cause bites to bleed, making the injury appear worse. These important defense mechanisms help water snakes survive predators such as raccoons, snapping turtles, foxes, opossums, other snakes, and birds of prey.
Common Water Snake populations are considered to be stable in Illinois. However, like many other water snakes, this species faces habitat loss and degradation. Unfortunately, they are also commonly killed by people out of fear.
#2. Plain-bellied Watersnake
- Nerodia erythrogaster
Identifying Characteristics:
- Adults have a thick body and range from 24 to 40 inches in length.
- Solid coloration of gray, brown, olive, or black.
- As the name suggests, they have a plain unmarked underside varying from red to yellow.
- Also called Redbelly, Yellowbelly, Copperbelly, or Blotched Watersnake.
The Plain-bellied Watersnake can be found near various water sources, including rivers, floodplains, lakes, ponds, and wetlands. This species spends an unusual amount of time on land compared with other water snakes found in Illinois. Especially during hot, humid weather, they can be found in woodlands quite far from a water source.
Plain-bellied Watersnake Range Map
Credit: Virginia Herpetological Society
They feed on BOTH aquatic and terrestrial prey, including crayfish, fish, salamanders, frogs, and other amphibians. Another unusual feature of this species is that they will sit and wait to ambush their prey, especially on land. Almost all other water snakes actively hunt and chase their victims!
The females give birth in August or September to live young. Litters average 18 young, but one of 55 has been reported! These unique water snakes can also produce offspring via parthenogenesis, a form of asexual reproduction in which an embryo develops without fertilization by sperm.
If captured, they release a foul-smelling musk and are not afraid to bite! Plain-bellied Watersnakes are eaten by largemouth bass, egrets, hawks, and sometimes other larger snakes.
#3. Queen Snake
-
Regina septemvittata
Identifying Characteristics:
- Adults are generally around 24 inches in length though individuals up to 36 inches have been reported.
- Coloration is drab brown or olive green with two lighter stripes down the sides.
- The underside is yellow or tan and also has four dark stripes that run the length of their belly. No other similar species has this feature!
Queen Snakes prefer moving water and are generally found near streams and rivers with rocky bottoms. They have highly permeable skin, making them susceptible to evaporative water loss. As you can imagine, they are rarely spotted far from water.
Queen Snake Range Map
Credit: Virginia Herpetological Society
Queen Snakes are considered to be less secretive than other water snakes in Illinois.
They are primarily diurnal and can be spotted basking on rocks, overhanging branches, or vegetation near the water’s edge. They often take refuge under rocks along the edges of streams. If you’re lucky, you may see them swimming.
These water snakes are specialist predators that primarily feed on crayfish. They almost exclusively prey on newly molted crayfish, which have soft bodies and can’t use their pinchers yet. They hunt by probing under rocks and other submerged objects for crayfish.
If disturbed, their first instinct is to flee into the water and dive below the surface. They typically will hide near the bottom briefly or swim down the shoreline before re-emerging. If cornered or captured, they will flatten themselves and may release a foul-smelling musk from glands at the base of their tail. Unlike other water snakes found in Illinois, they don’t typically bite.
#4. Northern Cottonmouth
- Agkistrodon piscivorus
Identifying Characteristics:
- Adults range from 26 to 35 inches in length. Females are typically smaller than males.
- Most individuals are dark gray to black with a broad head, heat-sensing pits between the eyes and nostrils, elliptical pupils, and a blunt snout.
- Some individuals have a brown, gray, tan, or blackish coloration.
- Also commonly called Water Moccasins, Black Moccasins, or Gapers.
Cottonmouths are the ONLY venomous water snake in Illinois.
Be on the lookout for these water snakes near swamps, marshes, ponds, and slow-moving streams and rivers, as well as flooded fields and drainage ditches. But they aren’t limited to just aquatic habitats. In Illinois, they can only be found in the extreme souther part of the state.
Northern Cottonmouth Range Map
Credit: Virginia Herpetological Society
Since Northern Cottonmouths are typically near water, the bulk of their diet is made up of fish and frogs. But they are opportunistic and will also eat small mammals, birds, turtles, small alligators, and other snakes.
These water snakes have several defensive tactics to warn potential threats to stay away! They often vibrate their tail in the leaf litter, pull their heads up and back, and then open their mouth to hiss and expose a white interior. This particular display is what earned them the name “cottonmouth.“
Since they are venomous, please use extra caution if you come across an unknown water snake. Quite a few species look similar, especially if you just get a glance as one moves across the water.
Luckily, receiving a bite from a Northern Cottonmouth is rare. But when it does happen, it is very serious as their venom destroys tissue. It is rare to die from their bite, but it does cause swelling and bruising and can leave scars.
#5. Diamond-backed Watersnake
- Nerodia rhombifer
Identifying Characteristics:
- Adults range from 30 to 48 inches in length.
- Coloration is brown, dark brown, yellowish, or olive green. Look for a dark chain-like pattern down the back.
- Thick body with a yellow belly that has dark half-moons.
The Diamond-backed Watersnake can be found in Illinois in a variety of freshwater habitats. They generally prefer slow-moving bodies of water with overhanging vegetation such as ponds and swamps and slow rivers and streams.
These water snakes are common in their range and can be spotted on overhanging branches looking for prey, which mainly include frogs and fish. Once they grab their target, they haul it to shore and wait for it to die before consuming it. This behavior is unique as most other water snakes consume their prey alive.
Diamond-backed Watersnake Range Map
Credit: U.S. Geological Survey, Department of the Interior/USGS
When disturbed, Diamond-backed Watersnakes will quickly flee into the water and dive below the surface to swim away. If captured, they will bite and release a foul-smelling musk from glands near the base of their tail.
They are relatively common and aren’t considered a threatened species. Unfortunately, they are sometimes killed out of ignorance. People often mistake them for venomous cottonmouths and rattlesnakes.
#6. Graham’s Crayfish Snake
- Regina grahamii
Identifying Characteristics:
- Adults range from 18 to 28 inches in length.
- Coloration is a dull brown, yellowish-brown, or gray.
- Look for yellowish-tan stripes down the sides and sometimes a faint tan stripe down the middle of the back.
This water snake is rather reclusive and hard to find in Illinois.
Look for Graham’s Crayfish Snakes in slow-moving bodies of water such as ponds, prairie streams, marshes, and roadside ditches. They prefer areas with abundant vegetation, rocks, logs, and other debris along the water’s edge, which allows them to hide from predators. Like other water snakes, they can commonly be seen basking on branches overhanging the water.
Graham’s Crayfish Snake Range Map
Credit: U.S. Geological Survey, Department of the Interior/USGS
As the name suggests, Graham’s Crayfish Snakes primarily feed on crayfish. They hunt exclusively for individuals that recently molted and temporarily have soft bodies. However, they’ll also prey on fish and amphibians, including tadpoles and frogs.
Like many other water snakes, this species is often mistaken for cottonmouths and killed, even though they are MUCH smaller.
#7. Kirtland’s Snake
- Clonophis kirtlandii
Identifying Characteristics:
- Adults range from 12 to 18 inches in length.
- Coloration is grayish brown, reddish, or dark brown with four rows of alternating, dark, round blotches down the back and sides.
- Bright red, pink, or orange underside.
- Mostly black or dark brown head with white, light-cream, or yellow lips, chin, and throat.
Kirtland’s Snakes are rarely found far from water in Illinois. They occupy various wetland habitats, including wet prairies, forested woodlands, floodplains, wet meadows, marshes, and swamps.
Kirtland’s Snakes are reclusive and nocturnal. They feed on small prey, primarily earthworms and slugs. They may also consume crayfish, leeches, small fish, insects, and grubs.
Kirtland’s Snakes are imperiled in all states within their range and are listed as endangered, threatened, or vulnerable. Habitat loss and degradation have played a significant role in the decline of this species. They also face threats from road mortality and the pet trade. Additionally, as these snakes rely heavily on crayfish burrows for shelter, so any reduction in crayfish populations is detrimental.
#8. Eastern Garter Snake
- Thamnophis sirtalis sirtalis
Identifying Characteristics:
- Adults typically range from 18 to 26 inches in length.
- Coloration varies and can be mixtures of green, brown, or black. Look for a distinct yellow or whitish stripe down the center of their back.
- Some individuals may exhibit a checkered body pattern.
- Subspecies of the Common Garter Snake.
Look for these snakes in Illinois basking in the sun in grassy areas near freshwater.
In fact, they are typically the snake species that people come across the most. They’re well-adapted to living around people and can often be found in city parks, farmland, cemeteries, and suburban lawns and gardens. Though not required, they prefer grassy environments near freshwater sources such as ponds, marshes, lakes, ditches, and streams.
Eastern Garter Snakes protect themselves when they are cornered or feel threatened. For example, if you capture or continually disturb one, it will defecate and release a foul-smelling musk from its glands. It’s also common for them to bite as a last resort!
The Eastern Garter Snake most commonly preys on toads, frogs, slugs, salamanders, fish, and worms. However, they are very opportunistic and will eat other insects and small animals they can overpower. They’re active during both the day and night, depending on the temperature.
#9. Western Ribbon Snake
- Thamnophis proximus
Identifying Characteristics:
- Adults range from 17 to 50 inches in length. A slender snake with a long tail!
- Coloration is blackish, brown, or olive with three light-colored stripes; one down the back and one down each side.
- The sides and top of the head are dark, and the upper lip is whitish.
Did you see a VERY long, slender snake in Illinois near freshwater?
If so, it was probably a Western Ribbon Snake! This semi-aquatic reptile is rarely found far from a water source. They typically occupy brush-heavy areas around streams, lakes, ponds, and other water bodies. You may also spot them basking on rocks, flat vegetation, and dry sandy areas near water.
The Western Ribbon Snake has an incredible, unique hunting technique. As they move over land, they make quick, light thrusts of their head and upper body in different directions in sequences of three. It’s similar to a strike, but with their mouth closed. This action disturbs resting frogs, which alerts them to their location. From there, this snake uses its superior speed to catch its prey.
When they feel threatened, they flee into the water or hide in thick brush. Their coloration provides superb camouflage in dense, brushier areas. If grabbed, Western Ribbon Snakes rarely bite but will thrash around, defecate, and release musk from their anal glands. This species can also shed its tail to escape, but unfortunately, it doesn’t regenerate like some lizard species.
#10. Plains Garter Snake
- Thamnophis radix
Identifying Characteristics:
- Adults average 36 inches in length.
- The coloration is gray-green with a distinctive orange stripe down the back and a greenish-yellow stripe down each side.
- Distinct light yellow spots on the very top of the head!
Plains Garter Snakes are almost always found in Illinois in prairies and grasslands near freshwater sources. They have a fairly large population and adapt well to human-modified landscapes. You may spot them near abandoned buildings, trash heaps, or vacant lots.
This species is considered one of the most cold-tolerant of all snakes! In fact, they will even come out of hibernation on warmer winter days.
Plains Garter Snakes feed primarily on earthworms, slugs, and small amphibians. However, they have also been observed preying on small mammals and birds, including the Eastern Meadowlark and Bank Swallow.
Do you need additional help identifying a water snake?
Try this field guide!
Which of these water snakes have you seen in Illinois?
Leave a comment below!
