Dopplefangers

To many people — far too many people — the only good snake is a dead snake. But for many species of snakes, the risk of being needlessly killed is multiplied because of an unfortunate case of mistaken identity — they are often confused for one of Missouri’s five species of venomous snakes.

Whether they share a habitat, color, or behavior, these snakes are often killed by people who mistake them for their venomous counterpart. Sometimes it’s a northern watersnake, confused for the venomous northern cottonmouth because they are both dark, aquatic species. Other times, it’s a prairie kingsnake, which shares some color similarity and a near statewide distribution with the eastern copperhead, Missouri’s most common venomous snake. Even the juvenile western ratsnake, before it grows into its familiar black skin, can find itself on the wrong end of a hoe for being mistaken for the massasauga rattlesnake.

But knowing what to look for, whether it be appearance (skin patterns, size, and shape), location and habitat, or typical behaviors, will help people distinguish the nonvenomous species from their venomous doppelgangers.

Bands and Blotches

Simply being a snake in or near the water is enough to condemn the northern watersnake to the same fear many have of the northern cottonmouth, according to State Herpetologist Jeff Briggler.

“By far these watersnakes and cottonmouths are the two most commonly misidentified snakes near water,” Briggler said. “Everybody believes every snake in the water is a cottonmouth, and it’s about 90 percent of the time or greater that is a northern watersnake.”

While both aquatic snakes share a dark hue, there are characteristics that can help distinguish the two, including physical and behavioral traits and their distribution throughout Missouri.

“Watersnakes have narrow necks,” he said. “And the cottonmouth will have a very defined neck and triangle-shaped head.”

While adult northern watersnakes and cottonmouths are roughly the same length, their bodies are noticeably different, he said.

“Venomous snakes, bodies are just robust and stout,” he said. “Watersnakes are generally more slender and narrow bodied. However, they can flatten their body to appear bigger, which confuses people because when they flatten out and spread their heads, it’s deceptive.”

And while both are dark, a closer examination of each snake’s color patterns can also help distinguish the two species. Snakes that are not a single color will typically have bands — unbroken strips that go from one side of the snake to the other — or blotches, he said.

“If you look at the crossbands on the northern watersnake, they’re the exact opposite of the cottonmouth — narrow at the base and wide in the middle of the back and become squarish blotches along the lower third of the body,” he said.

As cottonmouths age, they get darker, making the pattern difficult to distinguish. It may be necessary to rely on differences in behavior. Whereas most nonvenomous snakes will seek to flee from people, venomous species, including the cottonmouth, will often adopt a coiled, defensive posture.

“They’re giving you a warning,” Briggler said. “They’re coiling their body, opening their mouth widely and exposing the white coloration inside their mouth, hence their name. This is a sign to leave the snake alone.”

Stories abound of cottonmouths dropping out of streamside trees on unsuspecting canoeists, but it is, once again, another case of mistaken identity.

“Cottonmouths are not great climbers, not to say they wouldn’t climb into some small bushes on occasion, but they prefer to be on the ground.” he said. “When you see several snakes hanging over these bigger branches up high, a lot of times it’s a female watersnake with several males wanting to mate with her.”

As aquatic species, both take readily to the water, but even there, the two have different swimming styles, Briggler said.

“Northern watersnakes pop their heads up with a little bit of their body exposed, but when threatened they often dive,” he said. “Cottonmouths appear to float on the surface, usually with head held high and most of their body out of the water while swimming.”

In some cases, one of the easiest ways to distinguish between the two is to simply know where you are. There are no known populations of the cottonmouth north of the Missouri River, while the northern watersnake can be found virtually statewide.

The Dangerous Kiss

Sharing a brown or tan base color and near statewide distribution frequently puts the prairie kingsnake on the receiving end of animus meant for the eastern copperhead.

“There’s a strong overlap in distribution, and their habitat is pretty similar,” Briggler said. “They’re both going to be in areas where they can find rodents and other prey.”

Despite sharing a base color, the similarity ends there.

“The pattern is totally different,” he said. “Copperheads have the Hershey kiss or dumbbell shape crossbands along their body. The crossbands are wide along the sides and narrow in the middle, while the prairie kingsnakes will have rows of blotches, not bands, along the body. They also often have a little U- or V-shaped pattern on top of their heads.”

And like the cottonmouth, copperheads have a more triangular head than the kingsnake and are more likely to choose fight over flight.

“When threatened, copperheads are more likely to coil their bodies and hold their ground,” Briggler said. “Kingsnakes are either going to lie still and hope you don’t see them, and then if they think you did, they’re going to do their best to escape potential danger — slither into a hole, under rocks or logs, or into tall grasses.”

Just a Phase

For the western ratsnake, having a venomous doppelganger is just a phase. Because of its blotched color pattern and practice of vibrating its tail, as many nonvenomous snake species do to fool potential predators, the juvenile ratsnake is sometimes confused for the prairie massasauga rattlesnake, Briggler said.

“Just the pattern and the vibration of the tail sometimes makes people confuse it as some type of rattlesnake,” he said. “And when people look it up on the internet, the hatchling western ratsnake looks closest to the massasauga than anything else.”

As the western ratsnake matures, it loses its juvenile markings to become a long, shiny black, ending the resemblance and confusion. The western ratsnake is found statewide, while the massasauga is limited to relatively small tracts of bottomland prairie habitats in north-central and northwestern Missouri.

Live and Let Live

Even when knowing some of the differences between these snakes and their venomous lookalikes, sometimes circumstances — coloration of the snake on sunny versus overcast days, age of the snake, view of the entire snake, etc. — can make an informed identification difficult. That is why Briggler has simple advice for people who cross paths with a snake in the wild they can’t positively identify: leave it alone.

“Walk away,” he said. “You are more likely to be bitten attempting to kill a snake. I mean, the snake is threatened and upset, and it will readily defend itself, so live and let live.”

The Less Helpful Differences

While appearance, location and habitat, or typical behaviors can help distinguish Missouri’s nonvenomous from venomous lookalikes, there are several distinguishing features that are even more definite but less helpful because they require you to be much closer to the snake than most people like, especially when they are not certain of the snake’s species.

One feature that distinguishes Missouri’s venomous species from nonvenomous are the pupils. Venomous snakes have elliptical, catlike pupils, while nonvenomous snakes have round pupils. Venomous snakes also have a heat-sensing facial pit between the eye and the nostril that allows the snake to detect the body heat of a small mammal or bird, which is the origin of the term “pit viper,” which is absent in other snakes.

Venomous snakes also have fangs, which are used to deliver their venom, but once again, these are not obvious unless the snake opens its mouth, which is a bad time to be too close. Finally, venomous snakes have a single row of scales on the underside of their tails, compared to the double row of scales found in other snakes. The best time to discover this difference is when dealing with shed skin, rather than with a live snake.

Learning More About Missouri’s Snakes

When it comes to things we fear, snakes typically rank near the top of most lists, along with such heavy hitters as public speaking, heights, confined spaces, flying, and death. One way to address the fear of snakes is to become more knowledgeable of them, and MDC is here to help with two publications: A Guide to Missouri’s Snakes and The Amphibians and Reptiles of Missouri.

The 60-page brochure A Guide to Missouri’s Snakes provides readers with general information about snakes and detailed profiles with photos of 43 species of snakes, along with maps showing their range within the state. It is available online at short.mdc.mo.gov/45d and free at many MDC locations. Call ahead for availability. Missouri residents may order a free copy from pubstaff@mdc.mo.gov. Provide the publication title and your shipping address. Call 573-522-0108 to order by phone.

Updated in 2021 for the first time in more than 20 years, The Amphibians and Reptiles of Missouri is a 514-page guide to Missouri’s amphibians and reptiles that provides users with descriptions, distribution, habitats, habits, breeding, and other information on nearly 120 species of native salamanders, toads, frogs, turtles, lizards, and snakes. Illustrated with four-color photos and pen and ink drawings, this soft-cover guide includes updated taxonomy, common names, distribution maps, expanded Guide to Missouri’s Tadpoles, and a new section for established, nonnative species.

The Amphibians and Reptiles of Missouri is available for sale at most MDC nature centers, online at mdcnatureshop.com, or by calling toll-free 877-521-8632.