Is That Snake Venomous?

If you happen upon a snake while gardening or hiking, there’s a good chance you won’t know if it’s venomous at first glance. If you can resist the urge to run or to kill it, take a longer look. A visual check will help determine if the snake poses a danger. From a safe distance, look at:

1. The shape of its head. This is the easiest and most obvious indication of whether a snake is venomous or non-venomous. The head of a venomous snake is usually triangular or shaped like an arrow. Exceptions are the non-venomous Eastern hognose snake — which may flatten its head when threatened — and the coral snake.

2. Its eyes. Venomous snakes usually have a vertical, elliptical (cat-like) pupil, whereas the pupil of a non-venomous snake will be round and located in the center of its eyes. But there are some exceptions to this general rule, said Ross Baker, owner and founder of Oxbow Reptile in Duvall, Washington. Among those exceptions are the night snakes (Hypsiglena). Also look to see if there is a pit, or hole, between the snake’s eyes and nostrils or to the sides of the eyes. A venomous snake has a heat-sensitive pit or pits that enable it to locate warm-blooded prey, even in the dark. Non-venomous snakes lack these specialized sensory pits.

3. Its tail. Most venomous snakes have a single row of scales on the underside of the tail. The venomous coral snake is an exception because it has a double row. A double row is common in most non-venomous snakes. (This method of identification is best performed on a skin that has been shed, not on a live snake!)

It may take some courage for most people to perform field tests such as these. "A fear of snakes is one of the two most common phobias," said Judy DeLoache, a professor of psychology at the University of Virginia. DeLoache conducted a study with a colleague about what makes people so afraid of these slithering creatures.

The UVA studies showed how quickly people can detect a snake before something else. In a case where eight photographs of flowers and one picture of a snake were placed on a computer screen, people would see the snake faster than they would see the flowers, DeLoache said. In a second study involving very young children, the kids associated frightened voices with snakes more than with other creatures.

DeLoache believes there are two primary reasons humans have a fear of snakes. "Snakes have a unique body shape and movement pattern that is unlike any other creature," she said. "People have a fear and apprehension about things that are highly novel."

Frank Allen, a wildlife biologist with the Alabama Department of Conservation in Scottsboro, Alabama, says he even knows wildlife biologists who have a fear of snakes. "It’s ironic they even made it though a wildlife program," he said. "But," he added, "there’s no legitimate reason to have a fear of snakes."

Snakes, he points out, are helpful to humans in many ways and perform important roles in the natural environment. For one thing, they help control rodents and other pests, some of which could transmit diseases to humans. "I love to see a rat snake in my barn," he said. "They are also a food source for raptors like the red tail hawk."

To help you determine whether a snake you may unexpectedly encounter is one you might want to keep a healthy distance from or welcome to your garden or outbuilding, here’s a brief description of some of the most common venomous and non-venomous snakes in the United States.

First up, the venomous snakes

Only about 14% to 16% of all snakes are venomous, said Baker. In the United States, humans experience about 8,000 bites from venomous snakes each year, according to the American International Rattlesnake Museum in Albuquerque, New Mexico. Of those, an average of 12 per year, less than 1%, result in death. Far more people die each year from bee stings, lightning strikes or almost any other reason.

Rattlesnakes

Number of species: 32, with 65 to 70 subspecies.

Description: Rattlesnakes have a tail that ends with a rattle or a partial rattle, from which they get their name. The rattle is made of interlocking rings of keratin (the same material our fingernails are made of). Rattlesnakes warn of an impending attack by vibrating the rattle, which creates a loud hissing sound. A rattlesnake has two heat-sensitive "pits," one on each side of its head.

Range: North America and South America. Most rattlesnakes are concentrated in the southwestern United States.

Habitat: Rattlesnakes prefer a diverse range of dry habitats, including grasslands, scrub brush, rocky hills, deserts and meadows.

What you should know: Rattlesnake bites are the leading cause of snakebite injuries in North America and cause about 82% of fatalities. However, rattlesnakes rarely bite unless provoked or threatened. If treated promptly, the bites are rarely fatal.

Copperheads

Number of species: There are five subspecies. The northern copperhead (A.c. mokasen) has the largest range, inhabiting an area from northern Georgia and Alabama north to Massachusetts and west to Illinois. They are sometimes called the Highland moccasin because of their Highland habitat. The Native American word for these snakes is mokasen.

Description: Copperheads have an unmarked copper-colored head, and thick reddish-brown, coppery bodies with chestnut brown cross bands that constrict towards the midline. Their temperature-sensitive pit organ is on each side of the head between the eye and the nostril. Young copperheads have a sulfur-yellow-tipped tail. They grow to about 30 inches long, although the average and maximum lengths can be quite different, Baker said.

Range: The Florida Panhandle north to Massachusetts and west to Nebraska.

Habitat: Terrestrial to semi-aquatic areas, which includes rocky-forested hillsides and wetlands. Copperheads have also been known to occupy abandoned and rotting wood or sawdust piles.

What you should know: Copperheads are most active from April through late October, diurnal in the spring and fall and nocturnal during the summer. Many snakebites are attributed to copperheads, but the bites are rarely fatal. Bites occur when people accidentally step on or touch the snake, which tends to be well camouflaged in its surroundings. Sometimes when touched, they emit a musk that smells like cucumbers.

Cottonmouths

Number of species: There are three subspecies: the eastern, Florida, and western cottonmouths.

Description: The back is dark olive or black, the belly is paler. On young snakes, the back is marked by bands with dark borders and paler centers. This pattern is usually lost in older individuals. The snout is always pale, and there is usually a dark vertical line by each nostril. The banding pattern in the young may be striking. Newborn cottonmouths have brightly colored tail tips, which look like a worm. The average length is 30-48 inches, but occasionally can reach 74 inches.

Range: Cottonmouths are found mainly in the southeastern United States, from very southern Virginia to Florida and west to eastern Texas.

Habitat: These are semi-aquatic snakes and can be found near water and fields. They inhabit brackish waters and are commonly found in swamps, streams, marshes and drainage ditches. They also live at the edges of lakes, ponds and slow-moving streams and waters. They sun themselves on the branches, logs, and stones at the edge of the water.

What you should know: Many people know this snake as the water moccasin. "It is one of the few North American snakes with two commonly used names," Baker said. Cottonmouths are usually not aggressive and will not attack unless agitated. The snake will, however, "stand its ground," coiling its body and threatening who or what has alarmed it with its mouth wide open and fangs exposed, showing the white lining of its mouth, from which it gets its common name, cottonmouth.

Eastern coral snake

Genus/species: There are two species of coral snakes in the United States, the Eastern (Micrurus fulvius) and the Sonoran (Micruroides euryxanthus).

Description: Adults are usually 20 to 30 inches long. The head is black, followed by a wide yellow ring. The body has wide red and black rings separated by narrow yellow rings (sometimes white rings). The rings continue around the belly of the snake. The tail is black and yellow without any red rings. The pupil is round.

Harmless look-alikes: Two non-venomous snakes, the scarlet kingsnake (Lampropeltis elapsoides) and the scarlet snake (Cemophora cocinnea), are often confused with the Eastern coral snake. Here’s how to tell the difference. The Eastern coral snake has a black snout, while both the scarlet kingsnake and scarlet snake have red snouts. The rings on both the Eastern coral snake and scarlet kingsnake go all the way around the body, but the scarlet snake has a completely solid light-colored belly. Another way to tell the difference between the harmless mimics and the Eastern coral snake is to remember these mnemonic rhymes:

'If red touches yellow, it can kill a fellow.' (Eastern coral snake)

'If red touches black, it is a friend of Jack.' (scarlet kingsnake or scarlet snake)

Range: The Eastern coral snake occurs throughout Florida, south into the Upper Florida Keys. Outside of Florida, it is found north to southeastern North Carolina and west to eastern Texas and northeastern Mexico.

Habitat: This species occupies a variety of habitats, from dry, well–drained flatwoods and scrub areas to low, wet hammocks and the borders of swamps. They are quite secretive and are usually found under debris and in the ground. Occasionally they are found in the open and have even been seen climbing the trunks of live oaks. Good numbers of them are turned up when pine flatwoods are bulldozed, particularly in southern Florida.

What you should know: Because the Eastern coral snake is a relative of Old World cobras, people believe its bite nearly always is fatal. While its bite is serious and should receive immediate medical attention, statistics suggest that the bite of the Eastern coral snake is less threatening than the bite of an Eastern diamondback rattlesnake. "Coral snakes have very small 'fixed fangs' that are generally too small to penetrate human skin,” said Baker. “Their venom contains potent neurotoxins, unlike most pit vipers which primarily produce a hemotoxin."

Non-venomous snakes

Most of the world’s snakes are clinically non-venomous. This means they do not produce a toxin that is clinically significant to people. Many non-venomous snakes kill their prey by constriction, literally squeezing the life out of them.

Kingsnake

Genus/species: Kingsnakes are members of the genus Lampropeltis. There are five species and 45 subspecies.

Description: Kingsnakes have patterns of brightly colored stripes, bands or spots. The colors include yellow, red, brown and orange.

Range: Kingsnakes are among the most widespread snake species in the United States. They are found across the country are also in southern Canada and central Mexico. One species, the California kingsnake (Lampropeltis getulus californiae), is found in California as its name implies.

Habitat: Rock outcrops, brushy hillsides, river valleys, woodlands, fields and pine forests.

What you should know: The color pattern of the scarlet kingsnake (Lampropeltis triangulum elapsoides) resembles that of the venomous eastern coral snake (Micrurus fulvius). To tell the difference, remember the red-on-yellow red-on-black rhyme in the coral snake description. Kingsnakes are favorites for pets because of their bright colors. Because they are highly resistant to venom, they often kill and eat venomous snakes such as rattlesnakes, copperheads and cottonmouths. They perform another valuable service in helping to control rodent populations.

Corn snake

Genus/species: Elaphe guttata

Description: Corn snakes are slender and range in length from 24 to 72 inches. They are usually orange or brownish-yellow, with large, black-edged red blotches down the middle of the back. They have alternating rows of black and white marks that resemble a checkerboard pattern on their belly. Considerable variation occurs in the coloration and patterns of individual snakes, depending on the age of the snake and the region of the country in which it is found. Hatchlings lack much of the bright coloration of adults.

Range: Corn snakes are found in the eastern United States from southern New Jersey south through Florida, west into Louisiana and parts of Kentucky. They are most abundant in Florida and the Southeast.

Habitat: Corn snakes are found in wooded groves, rocky hillsides, meadowlands, woodlots, barns and abandoned buildings.

What you should know: Corn snakes are often mistaken for copperheads and killed. They are the most frequently bred snake species for pet purposes. Their name is believed to have originated from the similarity of the markings on the belly to the checkered pattern of kernels of maize or Indian corn. They are sometimes called the red rat snake.

Garter snake

Genus/species: Garter snakes belong to the genus Thamnophis. There are 28 species and even more subspecies.

Description: These snakes have a brown background color and longitudinal stripes in colors of red, yellow, blue, orange or white. They also have rows of blotches in between the stripes. Their name comes from the stripes, which resemble a garter.

Range: They are found throughout North America, from Alaska to New Mexico.

Habitat: Garter snakes are semi-aquatic and prefer habitats close to water.

What you should know: If disturbed, a garter snake may coil and strike, but typically it will hide its head and flail its tail. Garter snakes were long thought to be non-venomous, but recent discoveries have revealed they do, in fact, produce a mild neurotoxic venom. However, the venom is not fatal to humans, and they also lack an effective means of delivering it.

Black racer

Genus/species: Coluber constrictor priapus

Description: These snakes are usually thin with a jet black dorsal side with a gray belly and white chin. These snakes are sometimes killed because people mistake the white chin for the white mouth of the venomous cottonmouth.

Range: The black racer snake is found mainly in the Southern United States.

Habitat: Also known as a blue racer, blue runner and black runner, this snake tends to live in areas that are wooded. This includes forested areas, brushes, thickets, fields and the bigger gardens that are found in suburban yards.

What you should know: These are are fast-moving snakes, hence their name. They will use their speed to escape from most threatening situations. If cornered, however, they can put up a strong fight and will bite hard and repeatedly. The bites are not dangerous, but are painful. If they feel threatened, they have also been known to charge at people to frighten them or to vibrate their tails in leaves and grass in order to mimic the sound of a rattlesnake.

Ringneck snake

Genus/species: Diadophis punctatus

Description: Ringneck snakes are solid olive, brown, bluish-gray to black, broken with a distinct yellow, red, or yellow-orange neck band. A few populations in New Mexico, Utah, and other locations do not have the distinctive band. In some cases, the bands may be hard to distinguish or may be more of a cream color rather than bright orange or red. These are mostly small snakes, said Baker. "The largest, the regal ringneck, can reach 34 inches," he added.

Range: The ringneck snake is found throughout much of the United States, central Mexico and southeastern Canada.

Habitat: Moist forests, grasslands, hillsides, chaparral to desert streams.

What you should know: Ringneck snakes are rarely seen during the day time because they are secretive and nocturnal. They are slightly venomous, but their non-aggressive nature and small, rear-facing fangs pose little threat to humans. They are best known for their unique defense posture of curling up their tails, exposing their bright red-orange posterior when threatened.

Brown water snake

Genus/species: Nerodia taxispilota

Description: This is a heavy-bodied snake with a neck that's distinctly narrower than its head. Dorsally it is brown or rusty brown with a row of about 25 black or dark brown square blotches down its back. Smaller similar blotches alternate on the sides. Ventrally it is yellow heavily marked with black or dark brown.

Range: The brown water snake is endemic to the lower coastal regions of the Southeastern United States from southeastern Virginia, through North Carolina, South Carolina, and Georgia, to northern and western Florida (Gulf Coast), then west through Alabama and Mississippi, to Louisiana.

Habitat: They can be found in a variety of aquatic habitats, but are most common in flowing water such as rivers, canals and blackwater cypress creeks. Because of their preference for fish as a prey, they are largely restricted to permanent water bodies, including large reservoirs. Ideal habitat includes abundant overhanging vegetation, emergent snags, or rocky river banks where they can bask.

What you should know: Brown water snakes are proficient climbers and often bask on vegetation as high as 20 feet above the water. If startled, they will drop to the water and may accidentally end up in a passing boat. Although non-venomous, they are often mistaken for a venomous snake and will not hesitate to strike if cornered. They can inflict a painful bite.

Rough green snake

Genus/species: Opheodrys aestivus

Description: The rough green snake is bright iridescent green above and has a yellowish belly, affording it excellent camouflage in green vegetation. It is called "rough" because its scales stand out at a slight angle.

Range: The rough green snake is found throughout the Southeastern United States, from Florida, north to New Jersey, Indiana, and west to Central Texas. It is commonly found in the Piedmont and Atlantic Coastal Plain, but is not found in the higher elevations of the Appalachian Mountains. It is also found in northeastern Mexico, including the state of Tamaulipas and eastern Nuevo León.

Habitat: Sunny areas, low bushes and dense vegetation near water. They frequently climb bushes, vines and small trees and are rarely on the ground. Capable of catching prey in the air, they hunt for food during the day and sleep at night. Rough green snakes are excellent swimmers, often using the water to escape predators. “This is one of the few snakes that mostly feeds on insects,” Baker said.

What you should know: The rough green snake is docile and often allows close approach by humans. It seldom bites.

Eastern coachwhip

Genus/species: Masticophis flagellum flagellum

Description: This among North America's largest native snakes. Adults are long and slender, ranging from 50 to 72 inches. The longest on record was 102 inches. The head and neck are usually black, fading to tan posteriorly. Some specimens may lack the dark head and neck pigmentation. They have smooth scales and coloration that give the appearance of a braided whip, hence the common name.

Range: The Eastern coachwhip is found throughout Florida, except for the Florida Keys and from Texas, Oklahoma, and Kansas, east to North Carolina. However, it is absent from most of the Mississippi River delta.

Habitat: It can be found in a wide variety of habitats, but is most abundant in the Southeastern coastal plain. The preferred habitat includes sandy pine woodlands, pine-palmetto flatwoods, cedar glades, creeks, marshes and swamplands.

What you should know: This snake is considered to be high-strung in part because at times when first encountered it nervously vibrates its tail and strikes in an attempt to scare off a threat. However, most of the time it will flee quickly. One of its most remarkable traits is the speed with which it moves, racing along the ground or through vegetation.