Animal Diversity Web

Ge­o­graphic Range

Nero­dia fas­ci­ata is a non­ven­omous species with three dis­tinct sub­species (N. f. fas­ci­ata, N. f. con­flu­ens, and N. f. pic­tiven­tris). Col­lec­tively, these three sub­species are re­ferred to as south­ern water snakes and they are na­tive to the south­east­ern United States. The range of N. fas­ci­ata in­cludes east­ern Texas, south­east­ern Ok­la­homa, Arkansas, Louisiana, south­east­ern Mis­souri, west­ern Ten­nessee, west­ern and coastal Mis­sis­sippi, south­ern Al­abama, south­ern Geor­gia, Florida, and most of the Coastal Plain of North and South Car­olina. (Bartlett and Bartlett, 2005; Co­nant and Collins, 1998; Dor­cas and Gib­bons, 2004)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

Nero­dia fas­ci­ata is a gen­er­al­ist when it comes to fresh­wa­ter habi­tats, and in­di­vid­u­als are found in rivers, streams, lakes, reser­voirs, swamps, or small wet­lands. In­di­vid­u­als can tol­er­ate an av­er­age salin­ity that is less than 1.0 ppt, they will not sur­vive in any salt­wa­ter en­vi­ron­ment. (Bartlett and Bartlett, 2005; Dor­cas and Gib­bons, 2004; Ernst and Ernst, 2003)

• Habitat Regions
• temperate
• terrestrial
• freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Wetlands
• marsh
• swamp

Phys­i­cal De­scrip­tion

A dis­tin­guish­ing fea­ture of south­ern wa­ter­snakes is a dark stripe that ex­tends from the eye to the angle of the jaw, but other col­oration is vari­able. The base color can be gray, tan, dark olive, or black. The belly is typ­i­cally off-white or white. The dor­sal cross bands, which cover the en­tire body length, can also vary in color. Sub­species are dis­tin­guished based on band­ing pat­terns, color pat­terns, and ven­tral scale num­bers. Nero­dia f. fas­ci­ata has dark ven­tral mark­ings that are square-shaped and more than 128 ven­tral scales. Nero­dia f. con­flu­ens has dark body bands that are wider than N. f. fas­ci­ata, and only 11 to 17 bands are pre­sent along the length of the body as a re­sult. In­di­vid­u­als of N. f. con­flu­ens also have rec­tan­gu­lar, red­dish-brown spots on the sides of the ven­ter. Nero­dia f. pic­tiven­tris can have dark brown, black, or red­dish bands, dark lat­eral spots be­tween the bands, and wavy, red­dish trans­verse lines on the belly. Neonates are more vividly col­ored and pat­terned than adults.

Adult south­ern wa­ter­snakes range from 61 to 106.7 cm in length, whereas neonates tend to be about 24 cm long. These snakes ex­hibit sex­ual di­mor­phism in which fe­males are typ­i­cally longer and heav­ier than males. They have a stan­dard meta­bolic rate of 1.21cm3/h at 25°C. (Bartlett and Bartlett, 2005; Dor­cas and Gib­bons, 2004; Ernst and Ernst, 2003; Hop­kins, et al., 2004; Hop­kins, et al., 1999; Sem­listch and Gib­bons, 1982)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger

• Range mass

  113.5 to 246.9 g

  4.00 to 8.70 oz

• Range length

  61 to 106.7 cm

  24.02 to 42.01 in

• Average basal metabolic rate

  1.21 cm3.O2/g/hr

De­vel­op­ment

Young south­ern wa­ter­snakes are born alive. Fe­males carry their young dur­ing the spring and early sum­mer and give birth in the months of July, Au­gust, Sep­tem­ber, and Oc­to­ber. While the fe­males carry their young, the de­vel­op­ing em­bryos are nour­ished via a pla­centa. The ges­ta­tion pe­riod av­er­ages about 79 days, de­pend­ing on the tem­per­a­ture. It has been sug­gested that the ges­ta­tion pe­riod short­ens at higher el­e­va­tions but there is not enough re­search to sup­port such an as­ser­tion. Em­bryos can­not tol­er­ate tem­per­a­tures be­yond the 21 to 30°C range for the en­tire ges­ta­tion pe­riod; how­ever, the sex of the neonates is not de­pen­dent on tem­per­a­ture. After birth, young snakes can reach sex­u­ally ma­tu­rity in about two to three years. In­di­vid­u­als grow through­out their life­time but their growth rate de­creases with age. (Ernst and Ernst, 2003; Kofron, 1979; Viets, et al., 1994)

• Development - Life Cycle
• indeterminate growth

Re­pro­duc­tion

A fe­male will start ovu­lat­ing from early May to mid-June after awak­en­ing from a pe­riod of hi­ber­na­tion. Males pro­duce sperm in the fall that will be ready for sum­mer mat­ing. In­di­vid­u­als start mat­ing from early April to mid-June. Males have been seen con­gre­gat­ing in the water be­fore a pe­riod of mat­ing, but there is not enough field ev­i­dence to sug­gest that this species is in­deed polyan­drous. Males pur­sue fe­males. Once a fe­male is caught, the male will crawl an­te­ri­orly onto her back until the head of the fe­male is reached. When the head is reached, the male will pin it down and then he will po­si­tion his tail be­neath that of the fe­male, bring­ing their two vents to­gether. Cop­u­la­tion gen­er­ally lasts about 60 min­utes. (Dor­cas and Gib­bons, 2004; Ernst and Ernst, 2003)

Breed­ing sea­son varies with lo­cal­ity and sub­species. In gen­eral, the breed­ing pe­riod ex­tends from early April to mid-June. Fe­males ovu­late from May to June after awak­en­ing from a pe­riod of hi­ber­na­tion. They un­dergo vitel­lo­ge­n­e­sis, which in­cludes rapid yolk de­po­si­tion and fol­li­cle growth. Males pro­duce sperm in the fall, but they mate after emerg­ing from the hi­ber­na­tion pe­riod. Cop­u­la­tion takes at least 60 min­utes. As far as ges­ta­tion pe­riod is con­cerned, it is as­sumed to be­come short­ened at higher el­e­va­tions; how­ever, there is not enough re­search to sup­port such an as­ser­tion. The av­er­age ges­ta­tion pe­riod is about 79 days. Larger fe­males tend to have larger lit­ter sizes. Fe­males give birth as early as July and as late as Oc­to­ber. The av­er­age lit­ter size is about twenty, but there is no ev­i­dence sug­gest­ing that fe­males can have two lit­ters in one sea­son. (Dor­cas and Gib­bons, 2004; Ernst and Ernst, 2003; King, et al., 2009; Kofron, 1979; Krysko and King, 2010; Lorenz, et al., 2011)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• ovoviviparous

• Breeding interval

  Southern watersnakes breed once per year.

• Breeding season

  Southern watersnakes breed from early July to late October.

• Average number of offspring

  20

• Average gestation period

  79 days

• Range age at sexual or reproductive maturity (female)

  2 to 3 years

• Range age at sexual or reproductive maturity (male)

  2 to 3 years

There is no in­for­ma­tion about parental in­vest­ment in south­ern wa­ter­snakes in the lit­er­a­ture. How­ever, fe­males in­vest sub­stan­tially in pro­tect­ing the young in their cloaca dur­ing de­vel­op­ment and pro­vid­ing re­sources to the em­bryo. After birth, the young be­come in­de­pen­dent. (Ernst and Ernst, 2003)

• Parental Investment
• precocial
• female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • female

Lifes­pan/Longevity

In gen­eral, south­ern wa­ter­snakes ma­ture by the age of 3 and can live up to 7 or 8 years. The lifes­pan of south­ern wa­ter­snakes is de­pen­dent on the qual­ity and the quan­tity of their food. A male and fe­male mem­ber both sur­vived cap­tiv­ity for 3 years and 3 months. In gen­eral, in­di­vid­ual south­ern wa­ter­snakes do not live long in cap­tiv­ity. (Ernst and Ernst, 2003; Nielsen, 2011)

• Range lifespan
  Status: wild

  8 (high) years

• Average lifespan
  Status: captivity

  3 years

Be­hav­ior

The lit­er­a­ture sug­gests that south­ern wa­ter­snakes are sim­i­lar in be­hav­ior to other water snakes. Their move­ment pat­terns are sug­gested to be very sim­i­lar to north­ern wa­ter­snakes, Nero­dia sipedon. They use lat­eral un­du­la­tory move­ment and sidewind­ing for crawl­ing on the ground. Most wa­ter­snakes swim with their bod­ies fully sub­merged in water. In­di­vid­u­als also flick their tongues in order to gather chem­i­cal stim­uli from the en­vi­ron­ment. They are ac­tive both dur­ing the day and at night. In win­ter, they can be found hi­ber­nat­ing be­neath logs or rocks or in bur­rows. Dur­ing pe­ri­ods of ex­treme drought, south­ern wa­ter­snakes will leave the area, pos­si­bly to find a more suit­able aquatic habi­tat. It has been sug­gested that they are dri­ven away from an area af­fected by drought pri­mar­ily be­cause of the re­duced water lev­els as well as re­duced lev­els of aquatic prey. Al­though their num­bers may ini­tially drop dur­ing a drought pe­riod, these snakes re­cover sub­stan­tially af­ter­wards be­cause these snakes have a high fe­cun­dity rate. (Dagh­fous, et al., 2012; Dor­cas and Gib­bons, 2004; Ernst and Ernst, 2003; Seigel, et al., 1995; Will­son, et al., 2006)

• Key Behaviors
• natatorial
• diurnal
• nocturnal
• motile
• sedentary
• hibernation
• solitary

Home Range

Home range size is not re­ported in the lit­er­a­ture.

Com­mu­ni­ca­tion and Per­cep­tion

Snakes use their sense of sight, smell, and touch to nav­i­gate. They use vi­sual and ol­fac­tory cues to rec­og­nize preda­tors, prey, and their en­vi­ron­ment. South­ern wa­ter­snakes flick their tongue in order to col­lect smells from the en­vi­ron­ment, such as the scent of a nearby food item. There have not been many stud­ies, though, that focus solely on com­mu­ni­ca­tion and per­cep­tion in this species, but snakes gen­er­ally use pheromones in order to at­tract mates. (Dagh­fous, et al., 2012; Ernst and Ernst, 2003; Mason, et al., 1989)

• Communication Channels
• tactile
• chemical

• Other Communication Modes
• pheromones

• Perception Channels
• visual
• tactile
• vibrations
• chemical

Food Habits

South­ern wa­ter­snakes are di­etary gen­er­al­ists that un­dergo on­to­ge­netic changes from eat­ing pri­mar­ily fish as ju­ve­niles to eat­ing mainly frogs or large fish as adults. Young stay on a fish diet until they are about 6 months old. The type of fish and am­phib­ians that they con­sume will largely de­pend on the par­tic­u­lar area they in­habit, but some prey in­clude Amer­i­can eels (An­guilla ros­trata), pi­rate perch (Aphre­do­derus sayanus), banded pygmy sun­fish (Elas­soma zona­tum), Amer­i­can pick­erel (Esox amer­i­canus), top­min­nows (Fun­du­lus species), west­ern mos­qui­tofish (Gam­bu­sia affi­nis), least kil­li­fish (Heteran­dria for­mosa), white cat­fish (Ameiu­rus catus), bluegill sun­fish (Lep­omis macrochirus), spot­ted sun­fish (Lep­omis punc­ta­tus), rain­wa­ter kil­li­fish (Lu­ca­nia parva), bass (Mi­cropterus species), golden shin­ers (Notemigonus crysoleu­cas), south­ern toads (Anaxyrus ter­restris), spring peep­ers (Pseudacris cru­cifer), go­pher frogs (Litho­bates capito), and red-spot­ted newts (No­toph­thal­mus viri­descens). On oc­ca­sion, they prey on small tur­tles, small snakes, birds, earth­worms, and cray­fish. The en­larged gape of snakes al­lows them to con­sume large prey, but south­ern wa­ter­snakes have a dif­fi­cult time in­gest­ing prey items that are rel­a­tively heavy, short, and wide. (Dor­cas and Gib­bons, 2004; Ernst and Ernst, 2003; Vin­cent, et al., 2006)

• Primary Diet
• carnivore
  • piscivore

• Animal Foods
• birds
• amphibians
• reptiles
• fish
• terrestrial worms
• aquatic crustaceans

Pre­da­tion

South­ern wa­ter­snakes are pri­mar­ily preyed on by other snakes, great blue herons (Ardea hero­dias), and al­li­ga­tors (Al­li­ga­tor mis­sis­sip­pi­en­sis). In order to avoid pre­da­tion, in­di­vid­u­als es­cape into the water, en­large their pos­te­rior head re­gion, bite re­peat­edly, or se­crete a foul musk. They are also cryp­ti­cally col­ored, which makes them harder to find for preda­tors. (Dor­cas and Gib­bons, 2004; Vin­cent, et al., 2006)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • great blue herons (Ardea herodias)
  • alligators (Alligator mississippiensis)
  • other snakes (Serpentes)

Ecosys­tem Roles

South­ern wa­ter­snakes con­trol pop­u­la­tions of fish and am­phib­ians. Florida wa­ter­snakes (N. f. pic­tiven­tris) are car­ri­ers of the par­a­site he­mogre­garines (He­pa­to­zoon species), which is one of the most com­mon blood par­a­sites among snakes. (Vin­cent, et al., 2006; Woz­niak, et al., 1998)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

South­ern wa­ter­snakes are im­por­tant preda­tors of am­phib­ians and fish in aquatic habi­tats. (Vin­cent, et al., 2006)

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of these snakes on hu­mans.

Con­ser­va­tion Sta­tus

South­ern wa­ter­snakes are not threat­ened. They are abun­dant in ap­pro­pri­ate habi­tat and di­etary gen­er­al­ists. South­ern wa­ter­snakes are an ideal species to study in order to as­sess en­vi­ron­men­tal con­di­tions, such as water qual­ity. For in­stance, they have been used as focal stud­ies in re­search study­ing the ef­fects of ex­po­sure to coal com­bus­tion wastes on meta­bolic rates. (Dor­cas and Gib­bons, 2004; Hop­kins, et al., 1999)

• IUCN Red List

  Lower Risk - Least Concern

• US Federal List

  No special status

• CITES

  No special status

Other Com­ments

Nero­dia fas­ci­ata is often mis­taken for ven­omous cot­ton­mouths (Agk­istrodon pis­civ­o­rous) de­spite the dif­fer­ences in their phys­i­cal ap­pear­ance. As a re­sult, many south­ern water snake­sare mis­tak­enly killed by hu­mans. (Krysko and King, 2010)

Con­trib­u­tors

An­nette Cal­i­fano (au­thor), The Col­lege of New Jer­sey, Keith Pecor (ed­i­tor), The Col­lege of New Jer­sey, Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Bartlett, R., P. Bartlett. 2005. Guide and Ref­er­ence to the Snakes of East­ern and Cen­tral North Amer­ica. Gainesville, FL: Uni­ver­sity Press of Florida.

Co­nant, R., J. Collins. 1998. Rep­tiles and Am­phib­ians: Pe­ter­son Field Guides. New York: Houghton Mif­flin Com­pany.

Dagh­fous, G., M. Smar­giassi, P. Li­bourel, R. Wat­tiez, V. Bels. 2012. The func­tion of os­cil­la­tory tongue-flicks in snakes: in­sights from kine­mat­ics of tongue-flick­ing in the banded water snake (Nero­dia fas­ci­ata). Chem­i­cal Senses, 37/9: 883-896.

Dor­cas, M., J. Gib­bons. 2004. North Amer­i­can Wa­ter­snakes. Uni­ver­sity of Ok­la­homa Press.

Ernst, C., E. Ernst. 2003. Snakes of the United States and Canada. Wash­ing­ton: Smith­son­ian In­sti­tu­tion.

Hop­kins, W., J. Roe, T. Philippi, J. Con­g­don. 2004. Stan­dard and di­ges­tive me­tab­o­lism in the banded water snake, Nero­dia fas­ci­ata fas­ci­ata. Com­par­a­tive Bio­chem­istry and Phys­i­ol­ogy, 137: 141-149.

Hop­kins, W., C. Rowe, J. Con­g­don. 1999. El­e­vated trace el­e­ment con­cen­tra­tions and stan­dard meta­bolic rate in banded water snakes (Nero­dia fas­ci­ata) ex­posed to coal com­bus­tion wastes. En­vi­ron­men­tal Tox­i­col­ogy and Chem­istry, 18: 1258-1263.

King, R., R. Jadin, M. Grue, H. Wal­ley. 2009. Be­hav­ioural cor­re­lates with hemipe­nis mor­phol­ogy in New World na­tricine snakes. Bi­o­log­i­cal Jour­nal of the Lin­nean So­ci­ety, 98: 110-120.

Kofron, C. 1979. Re­pro­duc­tion of aquatic snakes in south cen­tral Louisiana. Her­peto­log­ica, 35: 44-50.

Krysko, K., F. King. 2010. "On­line Guide to Snakes of Florida" (On-line). Florida Mu­seum of Nat­ural His­tory. Ac­cessed Oc­to­ber 01, 2013 at http://​www.​flmnh.​ufl.​edu/​herpetology.

Lorenz, O., B. Horne, N. An­der­son, A. Cheek. 2011. Re­pro­duc­tive phys­i­ol­ogy of the broad banded water snake, Nero­dia fas­ci­ata con­flu­ens, in south­east­ern Louisiana. Her­peto­log­i­cal Con­ser­va­tion and Bi­ol­ogy, 6/3: 410-421. Ac­cessed Oc­to­ber 01, 2013 at http://​www.​herpconbio.​org/​Volume_​6/​Issue_​3/​Lorenz_​etal_​2011.​pdf.

Mason, R., H. Fales, T. Jones, L. Pan­nell, J. Chinn, D. Crews. 1989. Sex pheromones in snakes. Sci­ence, 245: 290-293.

Nielsen, A. 2011. "Water Snake" (On-line). Ac­cessed Oc­to­ber 30, 2013 at http://​www.​watersnake.​net/​.

Seigel, R., J. Gib­bons, T. Lynch. 1995. Tem­po­ral changes in rep­tile pop­u­la­tions: ef­fects of se­vere drought on aquatic snakes. Her­peto­log­ica, 51(4): 424-434.

Sem­listch, R., J. Gib­bons. 1982. Body size di­mor­phism and sex­ual se­lec­tion in two species of water snakes. Copeia, 4: 974-976.

Viets, B., M. Ewert, L. Tal­ent, C. Nel­son. 1994. Sex-de­ter­min­ing mech­a­nisms in squa­mate rep­tiles. The Jour­nal of Ex­per­i­men­tal Zo­ol­ogy, 270: 45-56.

Vin­cent, S., B. Moon, R. Shine, A. Her­rel. 2006. The func­tional mean­ing of “prey size” in water snakes (Nero­dia fas­ci­ata, Col­u­bri­dae). Oe­colo­gia, 147: 204-211.

Will­son, J., C. Winne, M. Dor­cas, J. Gib­bons. 2006. Post-drought re­sponses of semi-aquatic snakes in­hab­it­ing an iso­lated wet­land: in­sights of dif­fer­ent strate­gies for per­sis­tence in a dy­namic habi­tat. Wet­lands, 26/4: 1071-1078.

Woz­niak, E., S. Telford, D. DeNardo, G. McLaugh­lin, J. But­ler. 1998. Gran­u­lo­ma­tous he­pati­tis as­so­ci­ated with He­pa­to­zoon sp. meronts in a south­ern water snake (Nero­dia fas­ci­ata pic­tiven­tris). Jour­nal of Zoo and Wildlife Med­i­cine, 29/1: 68-71.