Reptiles of North Carolina
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NC Records

Nerodia sipedon - Common Watersnake


Photo: Steve Hall
Photo: Steve Hall
Photo: S. Chalasani
Taxonomy
Class: Reptilia Order: Serpentes Family: Colubridae Subfamily: Natricinae Other Common Name(s): Northern Water Snake
Taxonomic Comments: Nerodia, as currently considered, consists of ten species of semiaquatic, moderately large natricid snakes native to eastern and central North America, ranging from southern Canada down to the Gulf Coast of Mexico. For some time, North American members of this genus were considered part of the genus Natrix; Rossman and Eberle (1977) restricted Natrix to European taxa and resurrected Nerodia for North American species.

Species Comments: Nerodia sipedon, the Common Watersnake, is one of four Nerodia in North Carolina. This species ranges across the northeastern United States, from southern Canada to the Gulf of Mexico in extreme western Florida. West the species ranges as far as Colorado, though it is primarily restricted to the Midwest. It is largely absent from the southeastern Coastal Plain except where it ranges in the Outer Banks of North Carolina. In North Carolina, the species is found across the Piedmont and Mountain region, as well as down the Outer Banks and in parts of the northern Coastal Plain. It is absent from the southeastern Coastal Plain, and records from this region are instead likely representative of N. fasciata

This species occurs in a broad area of introgression with N. fasciata along the Fall Line, as well as in parts of the Coastal Plain. Some individuals in these areas cannot be morphologically assigned to one or the other species (Mebert, 2008).

Some authors recognize four subspecies. North Carolina is home to at least two of these: the nominate subspecies N. s. sipedon, the Northern Watersnake, across most of western North Carolina; and N. s. williamengelsi, the Carolina Watersnake, in the Outer Banks and part of the mainland Coastal Plain. The Midland Watersnake, N. s. pleuralis, may range up into parts of the Piedmont from South Carolina. Further taxonomic work is needed to determine whether the evolutionary history of these species matches the current subspecific designations.

N. s. williamengelsi is currently considered a North Carolina Species of Special Concern; as such, we have an additional page tracking records assignable to that population, pending further taxonomic clarification.

The generic epithet Nerodia is derived from the Greek neros, "flowing" or "liquid", and dia, "through". The specific epithet sipedon is derived from the Greek sepedon, "a serpent whose bite causes mortification". The subspecific epithet williamengelsi is in honor of William L. Engels, who studied the herpetofauna of Ocracoke Island prior to World War II.

Taxonomic References: Gibbons and Dorcas (2004); Mebert (2008); Walley et al. (2012).
Identification
Description: Common Watersnakes are large, stout aquatic snakes. Adult dorsal color is highly variable, but typically is varying shades of brown or gray with reddish to dark brown crossbands down the body; these crossbands are widest middorsally, narrowing laterally, and often tan or yellowish in the center. The venter is varying shades of white, yellow, or reddish, with dark semicircular spots.
Morphological Features: Common Watersnakes typically have 23 strongly keeled midbody scale rows. Ventral counts range from 123-155 (127-143 in NC specimens; Palmer and Braswell, 1995), with 42-84 (61-83) subcaudals and a divided anal plate. Head scale counts are typically: 8 supralabials, 10 infralabials, 1 loreal, 1 preocular, 3 postoculars, 2 nasals, and 1+2-3 temporals. Palmer and Braswell (1995) noted variation in scalation across multiple specimens in NC.

Common Watersnakes have a maximum recorded total length of 150 cm (59 inches). Palmer and Braswell (1995) reported a 133.1 cm female specimen from NC. Tail lengths account for approximately 21-29% of total length, though Nerodia often will be found missing portions of their tail. Females reach larger sizes than males; males have more subcaudals and longer tails on average.

Common Watersnakes do not have enlarged posterior teeth and do not produce venom. However, they will vigorously defend themselves when threatened. They will thrash, bite, musk, and may autotomize parts of their tails. Their can be painful, but they are otherwise not dangerous to humans or pets.
Technical Reference: Palmer and Braswell (1995); Ernst and Ernst (2003); Gibbons and Dorcas (2004)
Field Guide Descriptions: Palmer and Braswell (1995); Ernst and Ernst (2003); Gibbons and Dorcas (2004); Beane et al. (2010).
Online Photos:    Google   iNaturalist   GBIF
Observation Methods: Common Watersnakes are common in and near bodies of water. They can be occasionally encountered crossing roads between habitats.
Distribution in North Carolina
County Map: Clicking on a county returns the records for the species in that county.
Key Habitat Requirements
Habitat: Common Watersnakes occupy a broader range of habitats in the state than any other of our aquatic snakes. In the Piedmont and Mountains, they are associated with both still and flowing waters, occurring in lakes and ponds but also rivers, streams, and mountain brooks. In the Outer Coastal Plain, subspecies N. s. williamengelsi occurs in brackish tidal marshes and other tidewater habitats around the margins of Pamlico Sound.
Biotic Relationships: In part due to their broad geographic range, Gibbons and Dorcas (2004) reported that the diet diversity of Common Watersnakes is greater than that of any other watersnake. Fish are taken most commonly, followed by amphibians, but mammals and various invertebrates have also been found in the numerous diet studies of this species. It is likely that they will attempt to consume almost any fish they can successfully swallow, and published records include an impressive variety of fishes, including eels (Anguillidae), suckers (Catostomidae), sunfish and bass (Centarchidae, Elassomatidae, Moronidae), shad (Clupeidae), various minnows and shiners (Cyprinidae, Fundulidae, Umbridae), pickerel (Esocidae), catfish (Ictaluridae), mosquitofish (Poeciliidae), and trout (Salmonidae). Amphibians consumed include larval and aquatic salamanders (including mudpuppies, hellbenders, sirens, newts, ambystomatids, and plethodontids) and adult frogs and their tadpoles (including toads, spadefoot toads, cricket frogs, tree and chorus frogs, and true frogs). In addition, records of skinks, shrews, crayfish, dragonfly nymphs, earthworms, orthopterans, coleopterans, leeches, and various other invertebrates have been published, and cannibalism has been documented (Palmer and Braswell, 1995; Ernst and Ernst, 2003; Gibbons and Dorcas, 2004; Himes, 2004).

Documented predators of adult Common Watersnakes include alligators, snapping turtles, ophiophagous snakes (cottonmouths, kingsnakes, racers, and other watersnakes), raccoons, and predatory and wading birds (hawks, herons and egrets); largemouth bass and other large fish are known to consume juveniles (Ernst and Ernst, 2003; Gibbons and Dorcas, 2004).
Life History and Autecology
Breeding and Courtship: Male Common Watersnakes reach sexual maturity at snout-to-vent lengths of approximately 40 cm, while females are larger, typically 50–65 cm (Ernst and Ernst, 2003). Mating occurs in the spring and early summer (April to June), and a second mating period in September may occur in some populations.
Reproductive Mode: Common Watersnakes are viviparous; young are typically born in summer or fall (August and September) after a gestation period ranging from 56–84 days. Litters average more than 27 neonates, and large females tend to produce larger litters.

Neonates average approximately 21 cm in total length and weigh an average of 4 g.
Aquatic Life History: Common Watersnakes are semiaquatic and can be found in and around most permanent or semipermanent bodies of water within their range. Populations assigned to the subspecies N. s. williamengelsi are found in brackish and salt marshes, in addition to freshwater impoundments (Palmer and Braswell, 1995).
Terrestrial Life History: Like the closely related Southern Watersnake, Common Watersnakes may be most active at night, but diurnal activity is also frequently reported. They bask over or near water frequently and will hibernate under debris, in rock crevices, crayfish burrows, rotting stumps and logs near water. They have been recorded in North Carolina year-round; they are most active during spring and summer, and as a result most records are from April to August.

Home range estimates are not known from North Carolina. Elsewhere, home ranges have been reported to encompass a single body of water, but appear variable across the species’ range. In Missouri, home range estimates averaged 0.5 ha (5,000 m2; Roth and Greene, 2006); in Pennsylvania, 1.1 ha (11,000 m2; Pattishall and Cundall, 2008); and in Wisconsin, 3.4 ha (34,000 m2; Tiebout and Cary, 1987).
General Ecology
Adverse Environmental Impacts
Status in North Carolina
NHP State Rank: S5
Global Rank: G5

Photo Gallery for Nerodia sipedon - Common Watersnake

24 photos are shown.

Recorded by: J. Mickey
Wilkes Co.
Comment: With P. alleghaniensis/quadrivittatus		Recorded by: J. Mickey
Wilkes Co.
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Recorded by: Steve Hall, Dee Stuckey, and Savannah Hall
Durham Co.
Comment: 		Recorded by: Steve Hall, Dee Stuckey, and Savannah Hall
Durham Co.
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Recorded by: J. Mickey
Wilkes Co.
Comment: 		Recorded by: K. Hutson
Gaston Co.
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Recorded by: K. Hutson
Gaston Co.
Comment: 		Recorded by: Richard Teper
Orange Co.
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Recorded by: Shreyes Chalasani
Chatham Co.
Comment: 		Recorded by: Shreyes Chalasani
Chatham Co.
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Recorded by: Shreyes Chalasani
Chatham Co.
Comment: 		Recorded by: Travis McLain
Harnett Co.
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Recorded by: Travis McLain
Gaston Co.
Comment: 		Recorded by: Travis McLain
Gaston Co.
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Recorded by: Jessica Tate
Forsyth Co.
Comment: 		Recorded by: Jessica Tate
Forsyth Co.
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Recorded by: Travis McLain
Cabarrus Co.
Comment: 		Recorded by: Travis McLain
Stokes Co.
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Recorded by: Mark Shields
Polk Co.
Comment: 		Recorded by: Steve Hall
Richmond Co.
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Recorded by: Steve Hall
Orange Co.
Comment: 		Recorded by: Steve Hall
Orange Co.
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Recorded by: Steve Hall
Orange Co.
Comment: 		Recorded by: Steve Hall
Orange Co.
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