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Southern Water Snake

Nerodia fasciata

What do they look like?

Southern watersnakes have a dark stripe that extends from the eye to the angle of the jaw, but their colors otherwise vary a lot. The base color can be gray, tan, dark olive, or black. The belly is usually off-white or white. The bands on the back can vary in color as well. Young southern watersnakes are more vividly colored and patterned than adults. Adult southern watersnakes range from 61 to 106.7 cm in length, young are about 24 cm long. Females are generally longer and heavier than males. (Bartlett and Bartlett, 2005; Dorcas and Gibbons, 2004; Ernst and Ernst, 2003; Hopkins, et al., 2004; Hopkins, et al., 1999; Semlistch and Gibbons, 1982)

  • 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

Where do they live?

Southern watersnakes are nonvenomous water snakes found in the southeastern United States. The range 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)

What kind of habitat do they need?

Southern watersnakes are found in many kinds of freshwater habitats, such as rivers, streams, lakes, reservoirs, swamps, or small wetlands. They do not tolerate saltwater habitats. (Bartlett and Bartlett, 2005; Dorcas and Gibbons, 2004; Ernst and Ernst, 2003)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

How do they grow?

Young southern watersnakes are born alive. Females carry their young for about 79 days, depending on the air temperature, inside their body and give birth from July through October. While the females carry the young, the developing embryos are nourished via a placenta. After birth, young snakes can reproduce at two to three years old. Individuals grow throughout their lives, but their growth rate decreases with age. (Ernst and Ernst, 2003; Kofron, 1979; Viets, et al., 1994)

How do they reproduce?

Females are ready to breed after they awaken from hibernation, from early May to mid-June. Males are also ready to breed at this time. Males congregate in the water before a period of mating. (Dorcas and Gibbons, 2004; Ernst and Ernst, 2003)

Breeding season varies, depending on location. Breeding is generally from early April to mid-June. Females are usually pregnant for about 79 days. Females give birth as early as July and as late as October. Larger females tend to have larger numbers of young, the average litter size is about twenty. (Dorcas and Gibbons, 2004; Ernst and Ernst, 2003; King, et al., 2009; Kofron, 1979; Krysko and King, 2010; Lorenz, et al., 2011)

  • How often does reproduction occur?
    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

Southern watersnake females invest in their young through supplying the embryo with nutrients and gestating them until they are born live. After birth, the young are independent. (Ernst and Ernst, 2003)

How long do they live?

In general, southern watersnakes mature by the age of 3 and can live up to 7 or 8 years. Their lifespan depends on the quality and quantity of the food they eat. (Ernst and Ernst, 2003; Nielsen, 2011)

  • Range lifespan
    Status: wild
    8 (high) years
  • Average lifespan
    Status: captivity
    3 years

How do they behave?

Southern watersnakes are similar to other water snakes. They use lateral undulatory movement and sidewinding for crawling on the ground and swim with their bodies fully submerged in the water. Individuals flick their tongues to gather chemical cues 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 leave the area, possibly to find an aquatic area. (Daghfous, et al., 2012; Dorcas and Gibbons, 2004; Ernst and Ernst, 2003; Seigel, et al., 1995; Willson, et al., 2006)

Home Range

Home range size is not reported in the literature.

How do they communicate with each other?

Snakes use their sense of sight, smell, and touch to navigate and recognize predators and prey. Southern watersnakes flick their tongue in order to collect smells from the environment, such as the scent of a nearby food item. (Daghfous, et al., 2012; Ernst and Ernst, 2003; Mason, et al., 1989)

What do they eat?

Southern watersnakes eat many kinds of aquatic prey. Young eat mainly small fish and adults eat mainly frogs or larger fish. Prey species depend on what is locally abundant, but includes American eels, pirate perch, banded pygmy sunfish, American pickerel, topminnows, western mosquitofish, least killifish, white catfish, bluegill sunfish, spotted sunfish, rainwater killifish, bass, golden shiners, southern toads, spring peepers, gopher frogs, and red-spotted newts. On occasion, they prey on small turtles, small snakes, birds, earthworms, and crayfish. (Dorcas and Gibbons, 2004; Ernst and Ernst, 2003; Vincent, et al., 2006)

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

What eats them and how do they avoid being eaten?

Southern watersnakes are preyed on by other snakes, great blue herons, and alligators. To avoid predation, individuals escape into the water, enlarge their head, bite repeatedly, and 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)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Southern watersnakes control populations of fish and amphibians. Florida watersnakes (N. f. pictiventris) are carriers of a common blood parasite of other snakes. (Vincent, et al., 2006; Wozniak, et al., 1998)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • hemogregarines (Hepatozoon species)

Do they cause problems?

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

How do they interact with us?

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

Are they endangered?

Southern watersnakes are not threatened. They are abundant in appropriate habitat and eat a variety of prey. Southern watersnakes may be good indicators of aquatic habitat quality. (Dorcas and Gibbons, 2004; Hopkins, et al., 1999)

Some more information...

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.

 
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Califano, A. 2014. "Nerodia fasciata" (On-line), Animal Diversity Web. Accessed November 17, 2018 at http://www.biokids.umich.edu/accounts/Nerodia_fasciata/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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