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Snakes of this species are often killed by people who are afraid of them, and confuse them with venomous species, such as rattlesnakes. Northern water snakes will bite if you bother them, but they are not venomous.
Northern water snakes probably communicate with each other primarily through touch and smell. They also use their sense of sight and detection of vibrations to locate prey.
Communication Channels: tactile ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; vibrations ; chemical
Northern water snakes are abundant throughout their range.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Northern water snakes could potentially be a problem for fish hatcheries and fish farms.
Contrary to popular belief, northern water snakes are quite beneficial to fish populations. They feed on diseased and dying fish and help to control areas where overpopulation may exist and could stunt fish growth. This may actually help the sport fishing industry.
Northern water snakes control the populations of their primary prey, including fish, amphibians, and other reptiles.
Northern water snakes are carnivores and scavengers. They eat a variety of prey items, including amphibians (adults and tadpoles), fish (alive or dead), crayfish, large insects, leeches, other snakes, turtles, birds, and small mammals such as white-footed mice. They have been known to herd schools of fish or tadpoles to the edge of bodies of water where they can prey upon many at one time. Northern water snakes hunt both during the day and at night. They are not constrictors, they simply swallow their prey alive.
Animal Foods: birds; mammals; amphibians; reptiles; fish; carrion ; insects; terrestrial non-insect arthropods; aquatic crustaceans
Primary Diet: carnivore (Eats terrestrial vertebrates)
Northern water snakes are found in southern Ontario and the northeastern United States from Nebraska and Kansas in the west to the Atlantic coast and as far south as North Carolina and southern Missouri.
Biogeographic Regions: nearctic (Native )
Northern water snakes utilize many different aquatic habitats, such as: rivers, streams, sloughs, lakes, ponds, bogs, marshes, and impoundments. They prefer open areas that provide many spots for them to bask in the sun and relatively still waters. They may move onto land, especially the juveniles, but they never go to far from the aquatic environment. When they are not basking or searching for prey items they can be found beneath flat rocks, logs, boards or other types of cover. Northern water snakes are the most common snakes near water sources throughout northeastern North America.
Habitat Regions: temperate ; freshwater
Terrestrial Biomes: taiga ; savanna or grassland ; forest
Aquatic Biomes: lakes and ponds; rivers and streams
Wetlands: marsh ; swamp ; bog
Other Habitat Features: riparian
Northern water snakes have been known to live up to 9 years and 7 months in captivity. Their lifespan in the wild is unknown.
Range lifespan
Status: captivity: 115 (high) months.
Average lifespan
Status: captivity: 9.6 years.
These are dark-colored snakes, brownish, tan or grayish in appearance. The back and sides have a series of square blotches alternating with each other that may merge to form bands. Adult snakes can appear solid brown or black, especially when dry. The belly is usually white, yellowish, or orangish with dark half-moon-shaped black edges. Juveniles have reddish brown saddles on a tan, brown, or gray background. Males are usually smaller than females.
Scales are keeled and the anal plate is divided, with 21-25 scales at midbody.
Northern water snakes are medium to large snakes, ranging from 61 to 140 cm. They range from 19 to 27.3 cm at birth.
Range length: 61 to 140 cm.
Other Physical Features: heterothermic
Sexual Dimorphism: female larger
Northern water snakes often escape predators by swimming off across a body of water or by diving below the surface, where they anchor themselves to vegetation or logs. They usually remain submerged for about 5 minutes but are capable of remaining below water for an hour and a half.
When confronted, northern water snakes flatten their bodies and jaws and begin to strike and bite ferociously. They also release a foul-smelling musk and may defecate to discourage predators. When extremely agitated they will also regurgitate their last meal. Northern water snakes are preyed on by large snakes, such as milk snakes and racers, and by raccoons, skunks, and foxes.
Known Predators:
Mating System: polygynous
Male northern water snakes are able to reproduce when they are 21 months old. Female snakes begin to breed when they are three years old and produce a single litter each year. Most reproduction occurs while in or near their hibernation sites between mid-April and mid-June. Temperature and latitude may cause variation in these times.
During breeding, a male comes along side a female and rubs his chin along her back, occasionally giving a spasmodic jerk. He then twines his tail around hers and brings the cloacal openings into contact. Usually only one male copulates with a single female; on occasion there may be two.
Gestation can last anywhere from 3 to 5 months. Young snakes are born alive (not laid as eggs) from July to September. The litter ranges in size from 4 to 99 offspring. Larger females tend to have larger litters.
Breeding interval: Northern water snakes mate once yearly
Breeding season: April to June
Range number of offspring: 4 to 99.
Range gestation period: 3 to 5 months.
Average age at sexual or reproductive maturity (female): 3 years.
Average age at sexual or reproductive maturity (male): 21 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization ; ovoviviparous
Average age at sexual or reproductive maturity (male)
Sex: male: 730 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 730 days.
Female northern water snakes nurture and protect their young before they are born. Young water snakes become independent at birth, and are capable of hunting and caring for themselves.
Parental Investment: pre-hatching/birth (Provisioning: Female, Protecting: Female)
The common watersnake (Nerodia sipedon)[4] is a species of large, nonvenomous, common snake in the family Colubridae. The species is native to North America. It is frequently mistaken for the venomous cottonmouth (Agkistrodon piscivorus).
Common names for N. sipedon include banded water snake, black water adder, black water snake, brown water snake, common water snake, common northern water snake, eastern water snake, North American water snake, northern banded water snake, northern water snake, spotted water snake, streaked snake, water pilot, and water snake.[5]
The common watersnake can grow up to 135 cm (4 ft 5 in) in total length (including tail).[6] Per one study, the average total length of females was 81.4 cm (2 ft 8 in), while that of males was 69.6 cm (2 ft 3+1⁄2 in).[7] From known studies of this species in the wild, adult females can weigh between 159 and 408 g (5+1⁄2 and 14+1⁄2 oz) typically, while the smaller male can range from 80.8 to 151 g (2+7⁄8 to 5+3⁄8 oz).[8][9][10][11] The largest females can weigh up to 560 g (20 oz) while the largest males can scale 370 g (13 oz).[12][13]
N. sipedon can be brown, gray, reddish, or brownish-black. It has dark crossbands on the neck and dark blotches on the rest of the body, often leading to misidentification as a cottonmouth or copperhead by novices. As N. sipedon ages, the color darkens, and the pattern becomes obscure. Some individuals become almost completely black. The belly also varies in color. It can be white, yellow, or gray; usually, it also has reddish or black crescents.
The common watersnake is nonvenomous and harmless to humans, but superficially resembles the venomous cottonmouth. It is often killed by humans out of fear; killing snakes greatly increases the chance of being bitten.[14] The two can be easily distinguished: the watersnake has a longer, more slender body and a flattened head the same width as the neck, round pupils, and no heat-sensing pits. The cottonmouth has a fatter body, a wedge-shaped head with prominent venom glands that are wider than the neck, cat-like pupils, and heat-sensing pits between the eyes and the nostrils.[14]
Colubrid snakes also have flat scales on their heads, while vipers all possess smaller, rugose scutes.
These four subspecies are recognized as being valid:[2]
The common watersnake is found throughout eastern and central North America, from southern Ontario and southern Quebec in the north, to Texas and Florida in the south.[15] In 2007 an introduced population was discovered in California, where the related species N. fasciata has been introduced since at least 1992.[16][17]
While native to the eastern US, water snakes in California are considered invasive species likely to compete with native giant garter snake Thamnophis gigas, a threatened species.[17][18][19][20] Garter snakes in the western U.S. have filled the aquatic snake niche in the absence of true water snakes.[21] The common watersnake may threaten vulnerable fish and amphibian species via excess predation.[21] Common watersnakes are thought to have been introduced to western states as pets that were released.[21] In 2008 it was made illegal in California to own or import common watersnakes without a permit.[21]
N. sipedon is active during the day and at night. It is most often seen basking on rocks, stumps, or brush. During the day, it hunts among plants at the water's edge, looking for small fish, tadpoles, frogs, worms, leeches, crayfish, large insects, salamanders, other snakes, turtles, small birds, and mammals.[22] At night, it concentrates on minnows and other small fish resting in shallow water. It hunts using smell and sight. The Lake Erie watersnake subspecies, N. s. insularum, was once endangered, but now benefits from the introduction of the round goby, an invasive species, which constitutes up to 90% of its diet.
The common watersnake is common over most of its range and is frequently seen basking on stream banks, from which it dives into the water at the slightest disturbance. It is quick to flee from danger, but if cornered or captured, it usually does not hesitate to defend itself. Larger specimens can inflict a painful bite.
The common watersnake mates from April through June. It is ovoviviparous (live-bearing), which means it does not lay eggs like many other snakes. Instead, the mother carries the eggs inside her body and gives birth to free-living young, each one 19–23 cm (7+1⁄2–9 in) long.[23] A female may have as many as 30 young at a time, but the average is eight. They are born between August and October. Mothers do not care for their young. Multiple mating by females is common, leading to a focus in sperm competition. Research suggests successful males are not the ones who dedicate more energy to size, but to sperm.[24]
N. sipedon has many predators, including birds, raccoons, opossums, foxes, snapping turtles, other snakes, and humans. The common watersnake defends itself vigorously when threatened. If picked up by an animal or person, it will bite repeatedly, and release excrement and musk. Its saliva contains a mild anticoagulant, which can cause the bite to bleed more, but poses little risk to humans.
N. sipedon inhabits streams, lakes, and ponds, as well as wetlands. Juveniles typically inhabit lower-order streams adjacent to the larger-order waterways where adults are found. This helps juveniles to avoid predators such as fish, birds, and turtles present in large water bodies.[25]
The Lake Erie watersnake, which occurs mainly on the lake's western islands offshore from Ohio and Ontario, recovered to the point where on August 16, 2011, the U.S. Fish and Wildlife Service removed it from the Federal List of Endangered and Threatened Wildlife. The subspecies was first listed as threatened in 1999 after a decline due to eradication by humans, as well as habitat loss and degradation. When initially listed, the subspecies’ population had dropped to only 1,500 adults. Endangered Species Act protections for the snake included designation of 120 ha (300 acres) of inland habitat and 18 km (11 mi) of shoreline for breeding grounds. The introduction of an invasive species, the Eurasian round goby (Neogobius melanostomus) into Lake Erie in the mid-1990s became a new food source for the Lake Erie watersnake. By 2009, the population recovered to 11,980 snakes, safely exceeding the population minimum goal of 5,555 adult snakes required by the 2003 recovery plan. Monitoring was to occur for 5 years following this delisting. The Lake Erie watersnake is just the 23rd species or subspecies to be removed from the list due to recovery.[26]
Mature northern watersnake sunning itself near Battersea, Ontario
Preparing to moult, Prince Edward County, Ontario
Hunting on a beach near Georgian Bay, Ontario
Close-up of the head
Northern watersnake swimming in pond Hayesville, North Carolina
Basking in the sun along French Creek, Pennsylvania
N. s. insularum on Kelleys Island
The common watersnake (Nerodia sipedon) is a species of large, nonvenomous, common snake in the family Colubridae. The species is native to North America. It is frequently mistaken for the venomous cottonmouth (Agkistrodon piscivorus).
