North American Water Snakes: A Comprehensive Guide

North American water snakes

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Water snakes are only around 200 species of snake that are classed as semi-aquatic. They are usually found in aquatic environments, but spend time both in the water and on land. These are non-venomous snakes that are found across the Northern Hemisphere. In North America, there are several species of water snake that live here, and it’s important to be able to tell these apart from the dangerous cottonmouth.

Water Snake Habitat

Water snake habitat
Brown Water Snake (Nerodia taxispilota) Resting in the Reeds

In places like Georgia, Florida, and Mississippi, water snakes are among some of the most commonly encountered snakes by humans. While they’re not venomous, they may bite if they feel threatened.

You’ll find water snakes in and around water, as their name suggests. The bodies of water that they’ll hang around can vary greatly, with water snakes being reported around lakes, marshes, rivers, and ponds.

But they’re not always in the water. They will swim around the shallows but frequently come out to bask in the sun or climb trees. It’s unusual to find them far away from water.

Water Snake Diet

Water snake diet
Common Water Snake (Nerodia sipedon) Eating a Fish

The diet of the water snake is largely made up of aquatic animals such as fish and amphibians. They usually opt for slow-moving fish, especially when they are small. However, as they get bigger, these snakes will start preying on frogs and even things like salamanders.

These snakes are patient hunters and will sit in the water, mouths agape, waiting for prey to pass by. However, it’s not uncommon for them to go in pursuit of prey, looking among rocks and along the bottom of the water.

They aren’t venomous snakes in that they don’t deliver venom through their bite. However, research has shown that these snakes may have some mildly toxic compounds in their saliva.

Are Water Snakes Venomous?

While I have mentioned that water snakes may have very small amounts of mild toxins in their saliva, these are not harmful to humans. For all intents and purposes, these are not venomous snakes, although they can sometimes be confused with the water moccasin, sometimes called the cottonmouth, which is venomous.

It’s also important not to get water snakes mixed up with sea snakes. Sea snakes are venomous, with the Belcher’s sea snake being the most venomous. Its toxins could be potent enough to seriously harm or even kill a human.

But back to water snakes; while they aren’t venomous, they do respond to being handled by emitting a foul-smelling odor known as musk from their anal glands. Some will even poop when they are picked up. This gross-smelling musk serves as a warning to leave the snake alone.

Types of Water Snakes

The term water snake refers to more than one species. Below, I’ll talk about eleven of the most common water snakes in North America. Getting to know them better enables you to identify them and differentiate between these harmless snakes and their more dangerous cousins.

1. Common Water Snake (Nerodia sipedon)

Common Water Snake (Nerodia sipedon) is sometimes called the northern water snake, and is found in the northeastern parts of the United States and up into Canada.

The common water snake, sometimes called the northern water snake, is found in the northeastern parts of the United States and up into Canada. However, they’re also common as far south as North Carolina. The coloration of this species can vary but is usually brown to tan with dark markings and reddish bands.

These snakes prefer still waters but can be found in a wide variety of bodies, including lakes, streams, bogs, rivers, marshes, and ponds. Wherever they live, common water snakes like areas with open spaces which allow them plenty of room to bask.

The diet of the northern water snake is as varied as its habitat and consists of everything from amphibians and fish to insects, birds, and even other snakes. They’ll often scavenge, and when they catch their prey, they swallow it whole.

2. Diamondback Water Snake (Nerodia rhombifer)

Diamondback water snakes (Nerodia rhombifer) have a diamond-like crossed pattern on their backs.

As the name may suggest, diamondback water snakes have a diamond-like crossed pattern on their backs. They’re usually olive to dark brown in color but their markings tend to be closer to black.

Diamondback water snakes are found in rivers, swamps and other slow moving bodies of water. Within their range, they are one of the most common species and can be found in the southwestern United States. Although in some areas, such as Georgia and Indiana, they are considered vulnerable.

The diamondback water snake grows to between 30 and 60 inches (76 and 152 cm) by adulthood and is often compared to the salt marsh snake in appearance.

These snakes primarily feed on fish and have an unusual hunting technique in which they hang from tree branches over the water, waiting for their prey.

3. Banded Water Snake (Nerodia fasciata)

Banded water snakes (Nerodia fasciata) are incredibly abundant within the southeast.

The banded water snake is sometimes referred to as the southern water snake due to its distribution throughout the southeastern parts of the United States. This species can be found in almost any body of freshwater within its range.

Banded water snakes are incredibly abundant within the southeast, so much so that they’re often the subjects of studies and research. They feed on small fish when they are young, however their dietary needs change as they reach adulthood, when they’ll prey on larger fish and amphibians. Sometimes they will eat birds and turtles however, unlike other snakes, they find it difficult to digest very heavy prey.

These snakes can range in color from brown or black to reddish. They have dark banded markings along the body and a stripe that runs from the eye to the jaw.

4. Brown Water Snake (Nerodia taxispilota)

Brown water snakes (Nerodia taxispilota) are one of the most commonly confused with the water moccasin owing to the high position of their eyes.

Another snake found in the southeastern parts of the USA is the brown water snake. They are incredibly abundant and considered a species of least concern by the IUCN Red List. This species is quite large and can grow as long as 59 inches (150 cm). While the shade of brown can differ, most specimens have dark square shaped markings along the body, although on the underside, these markings can also be crescent shaped.

Brown water snakes are one of the most commonly confused with the water moccasin owing to the high position of their eyes. They’re also sometimes confused with rattlesnakes, of course, the lack of a rattle is a reliable way to identify them.

The brown water snake inhabits various bodies of freshwater but prefers those with things like logs and overhanging vines, which help them when hunting. They’ll use both foraging and ambush techniques to catch prey like fish, crustaceans, and amphibians.

5. Plain-Bellied Water Snake (Nerodia erythrogaster)

Plain-bellied water snakes (Nerodia erythrogaster) are considered threatened in some areas, including Ohio, Indiana, and Michigan.

Plain-bellied water snakes mainly inhabit the Panhandle to the west of the Ochlockonee River. However, this species is considered threatened in some areas, including Ohio, Indiana, and Michigan.

The plain-bellied water snake is a non-venomous species that grows to 48 inches (122 cm) at its largest. These snakes prey mainly on fish but are also a prey species themselves. When attacked, they will emit a smelly musk and may also flatten their bodies to the ground.

The coloration of the plain-bellied water snake (also called the red-bellied or yellow-bellied water snake) can vary greatly, from dark or light brown to olive and even gray.

6. Florida Green Water Snake (Nerodia floridana)

Florida green water snakes (Nerodia floridana) are the largest species of water snake in North America.

Growing up to 55 inches (140 cm) in length, the Florida green water snake is the largest species of water snake in North America. It is found in many parts of mainland Florida although absent from some areas, including the Florida Keys. They’re also common in Georgia and South Carolina. While common in most areas, numbers have declined in the northern part of their range.

These snakes prefer open marshy waters and aren’t often found in moving bodies, such as streams or rivers. There is still much to be discovered about how these snakes hunt, but it is known that their diet primarily consists of fish and, on occasion, frogs.

In some parts of their range, Florida green water snakes will hibernate during winter. However, for the most part, they are active year-round and may even be seen moving over the land in colder weather.

7. Concho Water Snake (Nerodia paucimaculata)

The concho water snake is a mid-sized species that typically grows to around 3 feet (0.9 meters) in length. However, since the mid-80s, this species has been considered vulnerable and at the time of writing, is listed as near threatened on the IUCN Red List.

Concho water snakes are found in Texas around the Concho and Colorado river basins however, habitat loss in this area is one of the main contributors to the snake’s declining numbers.

They enjoy free flowing water with lots of rocky areas where they can take shelter in between hunting for their main food source: fish.

8. Salt Marsh Snake (Nerodia clarkii)

Salt marsh snakes (Nerodia clarkii) are one of the few water snakes that prefer salt water.
Florida Fish and Wildlife / Flickr / CC BY-ND 2.0

Salt marsh snakes are one of the few water snakes that prefer salt water, as their name suggests, although they’re also found in brackish waters. They’re found along the gulf coast, but the areas in which they live are constantly being drained, which means there is a risk of these snakes becoming a threatened species.

In terms of diet, the salt marsh snake consumes mainly fish and crustaceans. They mainly hunt at night in order to remain safe from predators like aquatic birds and large crabs.

The salt marsh snake does not lay eggs but instead gives birth to live young. While they do not reach sexual maturity until around the age of three years, they have a long lifespan and can live up to 20 years in the wild.

9. Harter’s Water Snake (Nerodia harteri)

The harter’s water snake is sometimes called the Brazos water snake due to its habitat around the Brazos River in Texas; it is endemic to this area. If you’re keen to spot the harter’s water snake then be sure to look in rocky areas of the river where there is a lot of heavy vegetation.

The range of the harter’s water snake is no more than 1930 mi² (5000 km²) and for this reason the species is considered to be near threatened. However, the species is also protected by the Texas Parks and Wildlife Code.

Just like the salt marsh snake, the harter’s water snake gives birth to live young during the breeding season, which takes place in late summer to early fall.

10. Green Water Snake (Nerodia cyclopion)

Green water snake (Nerodia cyclopion) are sometimes referred to as the Mississippi green water snake.

The green water snake is endemic to the southeastern parts of the United States and is found in Illinois, Louisiana, and Mississippi, which is why it is sometimes referred to as the Mississippi green water snake.

The habitat of this species tends to be in slow moving bodies of freshwater like slow streams, marshes, and ponds. However, from time to time, the green water snake can be found in brackish water.

These are relatively heavy-bodied snakes that grow to a mid-sized length, however, some individuals may get as large as 55 inches (140 cm). They are dark in color and mainly prey on amphibians and fish as well as crayfish.

11. Copperbelly Water Snake (Nerodia erythrogaster neglecta)

Copperbelly water snakes (Nerodia erythrogaster neglecta) are found in Indiana, Michigan, and Ohio, and this small range is one of the reasons that numbers are so low.
Peter Paplanus from St. Louis, Missouri / Wikimedia Commons / CC BY 2.0

There has been a significant decline in the number of copperbelly water snakes and this is largely due to habitat destruction from drainage. However, this species is also hunted for collection for sale within the pet trade. Fortunately, this has been noted, and a permit is now required to collect them from the wild.

Copperbelly water snakes are found in Indiana, Michigan, and Ohio, and this small range is one of the reasons that numbers are so low.

These snakes are among some of the larger North American water snake species and can get as long as 60 inches (152 cm). The back is usually very dark in color, but the underside can be bright orange or reddish.

Copperbelly water snakes are known for their large litters, which are, on average, around 18 in number. However, there was one female that gave birth to 38 young in a single litter.

How to Tell the Difference between Water Snakes & the Venomous Cottonmouth?

How to tell the difference between water snakes & the venomous cottonmouth?
Venomous Cottonmouth Snake

The water snakes of North America are harmless although they may bite if they are aggravated, they aren’t venomous. However, it still pays to be really careful when interacting with nature as some species, such as the cottonmouth, looks remarkably similar to a water snake.

Cottonmouths, or water moccasins, are incredibly dangerous and a bite from one of these snakes could lead to the loss of limbs due to tissue damage. Not to mention, it’s incredibly painful and even in the best cases, you can expect a lot of pain and swelling. While rare, there are instances that cottonmouth venom could be fatal to humans.

Telling them apart from water snakes requires education, so allow me to point out some of the key differences between the two.

  • The body of a northern water snake tends to be long and thin, whereas that of a cottonmouth is much thicker and more heavyset.
  • Water snakes’ necks are the same size as their bodies, so it’s hard to tell them apart, making the snake look like one long continuation. On the other hand, cottonmouths’ necks are narrower than the head and therefore look more distinct.
  • Cottonmouths have much thicker and blockier heads compared to that of the water snake which is flatter and more slender.
  • Looking at the eyes, we can see that cottonmouths have a vertical pupil, whereas water snakes have a rounded pupil.
  • Water moccasins have heat-sensing pits on the face, but a water snake does not.
  • The cottonmouth typically has an eye stripe but this isn’t always seen on a water snake. 

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