Brown Watersnake vs Cottonmouth

Written by Brandi Allred
Updated: June 18, 2022
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Key Points

  • Cottonmouths have a hemotoxic venom that’s pretty dangerous, whereas brown watersnakes are not venomous or particularly dangerous.
  • The two snakes have a somewhat similar appearance. So, unfortunately, people sometimes misidentify brown watersnakes as cottonmouths and kill them.
  • There are a couple important distinctions to make between the appearance of the cottonmouth and brown watersnake.

There are many species of snake in the United States, but in the southeastern part of the country, two of these species stand out. These are the brown watersnake and the infamous cottonmouth. The two are very different species, yet they’re often confused for one another.

Here, we’ll learn exactly how to tell the difference between the two. Given that only one has a venomous bite, it’s important to know which is which. So join us as we discover all of the differences between brown watersnakes and cottonmouths. We’ll go over the appearance, preferred habitat, behavior, diet, and relative danger of each species.

Comparing Brown Watersnakes and Cottonmouths

Brown watersnakes and cottonmouths differ in appearance, preferred habitat, behavior, diet, and relative danger.

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Cottonmouth snakes are highly venomous, and people often kill them on sight. Sadly, brown watersnakes are often mistaken for cottonmouths and also killed. In the end, no matter what species of snake you’re looking at, it’s important to remember that it’s an important part of the native ecosystem and should be left alone.

There are a few big differences between brown watersnakes and water moccasins, but there are also similarities. Check out the table below to learn more.

Brown WatersnakeCottonmouth
SizeLength – 3.5 to 6 feetLength – 2 to 6 feet
ColorBrownBrown, black, olive
Body TypeSlender body with a relatively long, thin tailArrow-shaped head, nearly triangular when viewed from the top
TemperamentAggressive when provokedAggressive when provoked
LifespanUp to 9 years in captivity15 – 20 years

Key Differences Between Brown Watersnakes and Cottonmouths

Water Moccasin vs Cottonmouth Snakes
Cottonmouths have arrow-shaped heads.

The key differences between brown watersnakes and cottonmouths are appearance, preferred habitat, behavior, diet, and relative danger of each species.

We will discuss all of these differences in more detail below.

Brown Watersnake Vs Cottonmouth: Appearance

brown watersnake
Adult brown watersnakes range from yellow-brown to dark brown in color.

iStock.com/passion4nature

Brown watersnakes and cottonmouths, also known as water moccasins, are almost the same size. The biggest difference in size between the two is that, in cottonmouths, males are bigger than females. On the other hand, brown-banded watersnake males are much smaller than females.

Cottonmouths range in color from yellow-brown to red-brown, with older snakes tending to be darker in color. They have darker brown stripes encircling the lengths of their bodies. And, of course, cottonmouth snakes’ mouths are bright white on the inside. In contrast, brown watersnakes do not have stripes, though they share the same yellow-brown color of many cottonmouths. Brown watersnakes also don’t have lightly colored mouth interiors, and they don’t come in almost solid-colored variations like some cottonmouths do.

Brown Watersnake Vs Cottonmouth: Habitat

Both cottonmouths and brown watersnakes are endemic to the coastal states of the southeast, including Florida, Georgia, South Carolina, and North Carolina. Brown watersnakes live along the coast and lowlands, while cottonmouths live farther west along floodplains and sources of fresh water.

Brown watersnakes, like water moccasins, are semi-aquatic snakes. They rely on permanent water sources, like lakes and rivers, and are almost never found around impermanent sources of water, like floodplains.

Cottonmouths, on the other hand, will live anywhere there is water, even if that water is temporary. Brown watersnakes prefer flowing water like canals, cypress creeks, and rivers. Additionally, cottonmouths don’t climb more than a few feet high in trees, while brown watersnakes have been known to climb up to twenty feet up in trees overhanging rivers.

Brown Watersnake Vs Cottonmouth: Behavior

Juvenile Cottonmouth Snake swimming in a pond. They have even stronger contrasting bands of colors.
Cottonmouths are good swimmers; they hunt both on land and in water.

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While cottonmouths birth only 1-20 snakelings every 2-3 years, brown watersnakes birth between 20-60 snakelings at a time. Both species are active during the day and at night; they hunt whenever they can. Neither species is particularly aggressive, though brown watersnakes are known to deliver painful bites if humans get too close. Unfortunately, this happens all too often as brown watersnakes have a habit of falling into boats and canoes as they pass below on rivers.

Unlike cottonmouths, brown watersnakes have no brightly colored mouth interior. Cottonmouths often open their mouths and hold their ground in defense; brown watersnakes would much rather flee or hide than stand and fight.

Brown Watersnake Vs Cottonmouth: Diet

While both brown watersnakes and cottonmouths are common along water sources, only the brown watersnakes eat primarily fish. They’re both long, heavy snakes, but cottonmouths have a more varied diet than brown watersnakes. Both species are excellent swimmers, though brown watersnakes are much more likely to hunt along the edges of running water. They will even hunt along river bottoms. Because brown watersnakes feed almost exclusively on fish, like small catfish, they are found primarily around permanent sources of water.

Cottonmouths, on the other hand, will eat just about anything they can get their mouths around. Both species employ ambush and active foraging hunting strategies, though cottonmouths are much more likely to hunt both on land and in water. Cottonmouths eat everything from fish to baby alligators; their diet includes amphibians, small rodents, crayfish, turtles, and smaller snakes as well.

Brown Watersnake Vs Cottonmouth: Venom

close up of a brown watersnake
Brown watersnakes are not venomous, though they will bite to defend themselves.

iStock.com/passion4nature

Cottonmouths and brown watersnakes have very similar appearances, though only one of them poses any real threat to humans. While brown watersnakes are completely venomless, cottonmouths possess hemotoxic venom, which they inject using hollow, hypodermic needle-like fangs. Cottonmouths are pit vipers; they have the same kind of venom as copperheads and rattlesnakes. Like rattlesnakes, cottonmouths have two long, recurved fangs at the front of their mouth. These fangs are connected to venom glands located just below the eyes on either side of the skull.

Cottonmouth venom is rather potent- moreso than copperheads but less than rattlesnakes. The venom destroys tissue, causing pain and swelling. Cottonmouth bites sometimes result in permanent scars, and very rarely amputation or death.

Unfortunately, brown watersnakes are often killed by people who mistake them for the venomous cottonmouth. But, cottonmouths, though venomous, pose little threat to humans. In fact, they’re highly unlikely to bite, and even then, they may not inject venom. The exceptions to this rule come when people either step on them or purposely handle them, resulting in a bite.

Which Snake is More Dangerous?

When cottonmouths bite, their venom acts to pre-digest the flesh surrounding the bite and to begin shutting down the organs and inducing paralysis in the victim. Brown watersnakes, on the other hand, have no venom and can do more than bruise and puncture with their bite. Only one species can send a human to the hospital, and that’s the cottonmouth.

If a cottonmouth bites you, it’s important to move away from the snake rather than try to capture or injure it—this will likely result in additional bites. Once you’re a safe distance away, call 911, and get to a hospital as soon as possible. Cottonmouth bites rarely result in death or serious complications, but avoiding medical care greatly increases your chances of complications. Do not ice the bite, try to suck out the venom or make cuts over the puncture wounds. Instead, keep the bite below heart level, keep your heart rate low, and get to a hospital.

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