Nerodia

Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Lepidosauromorpha
Superordo: Lepidosauria
Ordo: Squamata
Subordo: Serpentes
Infraordo: Caenophidia
Superfamilia: Colubroidea

Familia: Colubridae
Subfamilia: Natricinae
Genus: Nerodia
Species: N. clarkii – N. cyclopion – N. erythrogaster – N. fasciata – N. floridana – N. harteri – N. paucimaculata – N. rhombifer – N. sipedon – N. taxispilota
Name

Nerodia Baird & Girard, 1853: 38

Type species: Coluber sipedon Linnaeus, 1758, by subsequent designation.

References
Primary references

Baird, S.F. & Girard, C. 1853. Catalogue of North American Reptiles in the Museum of the Smithsonian Institution. Part 1.–Serpents. Smithsonian Institution: Washington. xvi + 172 pp. BHL Reference page.

Additional references

Rossman, D.A. & Eberle, W.G. 1977. Partition of the genus Natrix, with preliminary observations on evolutionary trends in natricine snakes. Herpetologica 33(1): 34–43. JSTOR Reference page.

Links

Uetz, P. & Hallermann, J. 2021. Nerodia . The Reptile Database. Accessed on 26 June 2019.
Nerodia – Taxon details on Integrated Taxonomic Information System (ITIS).

Vernacular names
English: North American Water Snakes

Nerodia is a genus of nonvenomous colubrid snakes commonly referred to as water snakes due to their aquatic behavior. The genus includes nine species, all native to North America.

Description

Nerodia species vary greatly, but all are relatively heavy-bodied snakes, sometimes growing to 1.2 m (4 feet) or longer in total length. They have flattened heads, with small eyes that have round pupils, and keeled dorsal scales. Species like N. fasciata display distinct banding, whereas other species, like N. erythrogaster, have blotching, and those like N. rhombifer have diamond-shaped patterning. Most species are brown or olive green, or some combination thereof with markings being brown, or black. Yellow or cream-colored accenting is common.
Behavior

Water snakes, as their name implies, are largely aquatic. They spend the vast majority of their time in or very near permanent sources of water. Often, they can be found basking on tree branches that overhang slow-moving streams or ponds.
Diet

Their primary diet is fish and amphibians, and they are quite adept at catching both in their aquatic environment. They will also consume small reptiles and rodents that live near water.
Defense

While their initial instinct is to flee when disturbed, water snakes readily defend themselves if they are unable to escape. They do not often hesitate to strike or bite if handled, and often expel a foul-smelling musk from their cloacae.
Reproduction
Nerodia rhombifer, diamondback water snake, giving birth

Nerodia species are viviparous, breeding in the spring and giving birth in the late summer or early fall. They are capable of having 90 or more young, but broods generally are much smaller. Neonates are around 20–26 centimetres (8–10 in) in length.
Species and subspecies

These species and subspecies are recognized as valid:[1]

Nerodia clarkii (Baird & Girard, 1853) – salt marsh snake
N. c. clarkii (Baird & Girard, 1853)
N. c. compressicauda (Kennicott, 1860)
N. c. taeniata (Cope, 1859)
Nerodia cyclopion (A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854) – green water snake
Nerodia erythrogaster (Forster, 1771) – plainbelly water snake
N. e. alta (Conant, 1963)
N. e. bogerti (Conant, 1953)
N. e. erythrogaster (Forster, 1771)
N. e. flavigaster (Conant, 1949)
N. e. neglecta (Conant, 1949) – copperbelly water snake or copperbelly
N. e. transversa (Hallowell, 1852) – blotched water snake

N. e. transversa

, blotched water snake

Nerodia fasciata (Linnaeus, 1766) – banded water snake
N. f. confluens (Blanchard, 1923)
N. f.fasciata (Linnaeus, 1766)
N. f. pictiventris (Cope, 1895)
Nerodia floridana (Goff, 1936) - Florida green watersnake
Nerodia harteri (Trapido, 1941) – Brazos water snake
Nerodia paucimaculata (Tinkle & Conant, 1961) – Concho water snake
Nerodia rhombifer (Hallowell, 1852) – diamondback water snake
N. r. blanchardi (Clay, 1938)
N. r. rhombifer (Hallowell, 1852)
N. r. werleri (Conant, 1953)
Nerodia sipedon (Linnaeus, 1758) – common water snake
N. s. insularum (Conant & Clay, 1937)
N. s. pleuralis (Cope, 1892)
N. s. sipedon (Linnaeus, 1758)
N. s. williamengelsi (Conant & Lazell, 1973)
Nerodia taxispilota (Holbrook, 1842) – brown water snake

Distribution

Nerodia species are widely spread throughout the southern and eastern half of the United States, north into Canada and south into Mexico, as well as to the island of Cuba. Many ranges overlap, and intergrading of subspecies is not unknown, but is rare. Two species of Nerodia are invasive in the southwest US.[2]

N. clarkii - around the Gulf of Mexico (Florida, Louisiana, Mississippi, Texas) and Cuba
N. cyclopion - Texas, Louisiana, Arkansas, Missouri, Illinois, Mississippi, Alabama, Georgia, Florida, South Carolina, Tennessee, and Kentucky
N. erythrogaster - Texas, Oklahoma, Kansas, Louisiana, Arkansas, Missouri, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, Illinois, Indiana, Ohio, Michigan, Iowa, Delaware and into Mexico (Durango, Zacatecas, Coahuila, and Nuevo León)
N. fasciata - Texas, Louisiana, Oklahoma, Arkansas, Mississippi, Alabama, Florida, Georgia, South Carolina, North Carolina, Missouri, and Illinois
N. harteri - west-central Texas
N. paucimaculata - Central Texas
N. rhombifer - Texas, Oklahoma, Kansas, Louisiana, Arkansas, Missouri, Illinois, Indiana, Tennessee, Mississippi, and Alabama, as well as south into Mexico (Coahuila, Nuevo León, Tamaulipas, and Veracruz)
N. sipedon - Colorado, Nebraska, Kansas, Oklahoma, Iowa, Missouri, Arkansas, Minnesota, Wisconsin, Illinois, Tennessee, Louisiana, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, Kentucky, West Virginia, Virginia, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire, Maine, Massachusetts, Rhode Island, Connecticut, New Jersey, Delaware, Maryland, Michigan, and north into Canada
N. taxispilota - Florida, Alabama, Georgia, South Carolina, North Carolina, and Virginia

In captivity

Due to how widespread and extremely common they are in the wild, water snakes are often found in the exotic pet trade, throughout the United States, though they are rarely captive bred. Their relative physical unattractiveness, compared to other available pet snake species, and their poor disposition make them less than attractive pets. They are easy to care for, though, and do quite well in captivity.
Conservation concerns

Some species, such as N. harteri and N. paucimaculata are only found in very isolated localities and are protected by state laws, but the majority of Nerodia species hold no specific conservation status. Due to their habitat choice, poor disposition, and vague similarity to the venomous cottonmouth (Agkistrodon piscivorus), they are frequently mistaken for them. This results in many more water snakes being killed every year than cottonmouths. Often, water snakes found in areas where the cottonmouth does not range are still killed by humans out of ignorance and fear.
References

ITIS (Integrated Taxonomic Information System). www.itis.gov.

"California Nerodia Watch - iNaturalist".

"Nerodia". Integrated Taxonomic Information System. Retrieved 12 May 2006.
Northern Water Snake Species account from the Iowa Reptile and Amphibian Field Guide
Diamondback Watersnake - Nerodia rhombifer Species account from the Iowa Reptile and Amphibian Field Guide