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Invasive Reptiles and Amphibians

Southern Watersnake

  • Scientific Name

    Nerodia fasciata - Visit ITIS for full scientific classification. 

  • Description


    • Dark-colored, heavy-bodied snakes.
    • Can be black, brown, tan, reddish, yellowish, or gray in color, with crossbands.
    • Coloration varies between the three subspecies: Florida, Banded, and Broad-banded.
    • Bellies are marked with square or triangular shaped markings.
    • Possible for individuals to get up to 5 feet long.
    • Not a venomous snake, but they can aggressively bite and discharge a musky, foul-smelling substance when threatened.
  • Habitat
    • Found in a wide variety of freshwater habitats including: ponds, lakes, ditches, streams, rivers, etc.
    • Also found in some brackish water habitats including swamps and marshes.
    • Usually found basking in the sun, or hiding in burrows or under vegetation. 
  • Invasion Pathways and Distribution
    • Watersnakes make poor pets, but are still found in the pet trade.
    • Therefore, the most likely pathway of introduction to non-native areas is release from pet owners.
    • Native to Florida and the eastern U.S.
    • Now found in some areas of California.
    • See USGS for a map of current U.S. distribution. 
  • Life History
    • Mothers retain eggs internally and give birth to live young in the summer and fall.
    • Juveniles are paler and have stronger patterns than the adults.
    • Other details including life span, litter size, and mating behaviors may differ between subspecies.
  • Impacts
    • Predators that feed on a variety of different animals including fish, amphibians, worms, turtles, birds, etc.
    • Individuals can travel across land for over a mile to find more food and new habitats.
    • Their ability to disperse, in combination with their tolerance for brackish water, as well as their varied diet, gives them the potential to threaten native species including California's garter snakes. 
  • References and Useful Links

    For references by category and links to other useful AIS sites see our Learn More page.