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Invasive Reptiles and Amphibians

Northern Watersnakes

  • Scientific Name

    Nerodia sipedon - Visit ITIS for full scientific classification. 

  • Description


    • Dark-colored, heavy-bodied snakes.
    • Four subspecies: Lake Erie, Midland, Carolina, and Common.
    • Usually a tan, brown, or gray color with black, dark brown, or reddish colored crossbands.
    • White or yellowish colored bellies with dark half-moon shaped markings.
    • Possible for individuals to get up to 4.5 feet long.
    • Males are usually smaller than females.
    • Not a venomous snake, but they do bite and can discharge a musky, foul-smelling substance when threatened. 
  • Habitat
    • Found in a wide variety of freshwater habitats including: ponds, lakes, ditches, streams, rivers, etc.
    • Prefers sunny locations, and shallow waters for basking.
    • When not basking, they are found hiding under rocks, driftwood, debris, or other natural or man-made structures. 
  • 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 Eastern U.S.
    • Now found in some areas of California.
    • See USGS for a map of current U.S. distribution.
  • Life History
    • Mating can take place on land or in the water, and usually occurs in the spring.
    • Mothers retain eggs internally and give birth to live young in the summer.
    • Sexual maturity occurs at around 2 or 3 years of age.
    • Average lifespan in the wild is unknown, but an individual in captivity was reported to live almost 10 years. 
  • Impacts
    • Predators that feed on fish, amphibians, and invertebrates.
    • Established populations of Northern Watersnakes could decrease the number of native species due to predation.
    • Also, increased numbers could threaten California's native garter snakes through direct competition. 
  • References and Useful Links

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