By Alvin Braswell, Curator of Reptiles and Amphibians
How many species of venomous snakes live in North Carolina?
Six: copperhead, cottonmouth, timber rattlesnake, pigmy rattlesnake, eastern diamondback rattlesnake and eastern coral snake. There are also 31 nonvenomous species in North Carolina, for a total of 37 species.
Although the eastern coral snake possesses very powerful venom, it is rare in the state and no bites have been recorded. The eastern diamondback rattlesnake has a large quantity of venom that is more toxic than that of the timber rattlesnake, pigmy rattlesnake, cottonmouth or copperhead. However, it, too, is quite rare.
The copperhead (pictured above right) can be considered the most dangerous in North Carolina simply because in many areas of the state, it is the only venomous snake you are likely to encounter. The copperhead is more likely to occur near human dwellings than other venomous species, and it is responsible for the vast majority of venomous snakebites.
Fortunately, copperhead venom is relatively mild. The bites are painful, but deaths from copperhead bite are extremely rare. When proper medical assistance is received, the bite normally causes no permanent injury. Medical assistance should always be sought for any venomous snakebite.
Five of North Carolina’s six venomous species are pit vipers. The distinguishing feature is the heat-sensing pit, or indentation, between the eye and nostril on each side of the head (lateral head figure, right). The pits face forward and are used to detect differences in temperature. The snakes’ “binocular” heat-sensing ability allows them to detect in total darkness the location and probably the size of warm-blooded animals. This faculty is primarily used to acquire food—just as snake venom is. However, it also can help snakes detect the presence of animals that might prey upon or otherwise harm them.
All pit vipers have vertical, elliptical pupils, and most of the scales under the tail are in a single row, (tail figure, left) although these characteristics can be difficult to observe.
The eastern coral snake is the one venomous species in North Carolina that isn’t a pit viper. It has many characteristics in common with the 31 nonvenomous snakes, which have round pupils, no pit and a double row of scales under the tail (tail figure, right).
You can reduce the likelihood of their presence near your residence by removing items they might use for shelter – or which their prey might use -- such as scrap sheet metal, boards, woodpiles and similar debris. Raising materials off the ground promotes dryer storage and attracts fewer critters. When woodlands and other plant communities are nearby, eliminating the possibility of a snake is virtually impossible. Learn to identify the dangerous species in your area, and be cautious when conducting activities that could promote encounters (e.g., don’t walk around barefooted outdoors at night when the copperhead is on the prowl for food).
More species of snakes occur in the Coastal Plain (36) than in the Piedmont (29) or the mountains (21). In most habitats, nonvenomous snakes far outnumber venomous snakes in both number of species and number of individuals. One or more species of snakes are likely to occur in most natural habitats that are not intensively manicured. Riparian habitats along stream corridors probably have the highest diversity of snakes.
Snake diets vary widely depending on the species. Some prefer warm-blooded prey and eat mostly rodents and birds, while others prefer amphibians, other reptiles, fish, insects, spiders, earthworms, slugs and a variety of other invertebrates. Most snakes eat once a week to once a month, depending on the size and availability of food.
In North Carolina, chances are excellent that the snake involved is a rat snake. (Rat snake shed pictured at right) This species is an excellent climber and is responsible for most of the “snake-in-house” calls the Museum of Natural Sciences receives. If you need to verify the identification, collect as much of the shed as possible, put it in a protective container and send it to a science center or natural history museum for identification. The Museum will identify the shed or will help you locate someone in your area who can help. Once snakes shed their skin, they usually go in search of food. If a shed is dry, chances are the snake is not present. Shed skins normally are longer than the snake that shed them by about 25% (e.g., a 5-foot shed would be from a 4-foot snake).
Most snakes shed three or more times each year. They usually shed shortly after emerging in the spring. After that, sheds are geared to the growth rate and general health of the snake. A snake with a skin infection or injury might shed more often than normal. A young, growing snake will shed more often than an older, mature one.
The most common snake in North Carolina very likely is the eastern worm snake. The largest one recorded from the state was 330 mm (13 inches). It is usually seen when dug up or uncovered while moving objects such as logs or mulch. The rat snake and black racer also are commonly seen large snakes that are active by day and live in habitats frequented by humans.
The eastern diamondback rattlesnake possesses this dubious distinction, closely followed by the eastern coral snake. Both are on N.C.’s endangered species list.
Loss of habitat and declining numbers landed two venomous snake species on N.C.’s endangered species list in 2001. Two additional venomous and four nonvenomous species are classified as N.C. “species of Special Concern” for the same reasons. These designations make it illegal to collect the snakes without a permit. Killing them is allowed only when they pose a clear and imminent threat to health and safety. All plants and animals are protected within the boundaries of national and state parks, as well as in some other nature preserves and sanctuaries.
Eight of the North Carolina’s 37 snake species receive protection under the state’s endangered wildlife law:
Some eat rats and mice that damage crops and property, and carry diseases; all are important parts of their ecosystems. Some also have beautiful colors and markings, and many help people learn about the natural world. Snake venoms have been used in a variety of medical applications. In some parts of the world, snakes are considered valuable food items, prized for high-priced leather products and revered as mythical creatures.
If you need more information or have more questions about North Carolina snakes, please Ask a Naturalist.