Northern Water Snake

Nerodia sipedon

The Northern Water Snake (Nerodia sipedon sipedon) is a medium-sized, non-venomous, Colubrid snake of Eastern North America. It is found in a variety of aquatic habitats, such as lakes, rivers, and wetlands, as well as man-made ditches and retention ponds.

How do I Identify a Northern Watersnake?

Northern Water Snakes typically have dark dorsal (back) bands that are present on the anterior (towards the head) portion of the body that change to alternating dorsal (back) and lateral (side) blotches. Their ventral (belly) scales usually have dark half-moon shaped markings on them. Be aware that there can be a lot of variation within this general description! (Many water snakes can look very different from this!)

Unfortunately, water snakes are often confused and misidentified as venomous Cottonmouths or Copperheads. Some simple characters are present that can help the non-herpetologist distinguish between watersnakes and their venomous counterparts. First is the general shape of their head, although this is not the most reliable. Venomous snakes such as the Cottonmouth and Copperheads have a triangular shaped head that is very wide at the base due to the presence of the venom glands. However, to the untrained eye, defensive posturing (flattening and widening of the head and body) of many species of water snakes can be misleading. Fortunately, two other characters are present on the head of the animal to help the confused observer. Non-venomous water snakes have round pupils, not elliptical shaped (cat eyes), like those of venomous species. Finally, on a Northern Water Snakes, there will be no heat sensing PIT organ on the either side of the head between the eye and nostril. In addition to the head characteristics, Northern Water Snakes typically swim with their body below the water (just the head above the surface), while venomous snakes like the Cottonmouth swim on top of the water.

What do Northern Water Snakes eat?

Water snakes eat primarily aquatic prey items such as small fishes and amphibians (frogs and salamanders), but on rare occasions, they have been found to eat invertebrates (worms, leeches, crayfish) and small mammals (shrews and voles). Recently, some populations have started feeding upon the introduced Round goby, an invasive species. Snake diets can also differ based on age or sex.

What eats Northern Watersnakes ?

Predators of the Northern Water Snakes include birds, raccoons, opossums, foxes, snapping turtles, and other snakes.

How do Northern Watersnake reproduce?

Northern Water Snakes are live-bearing snakes! They mate in the early Spring and give birth in late summer to several pencil-sized young. The number of babies an individual female water snake can produce in a litter (or clutch) is highly dependent on a number of factors (like how much food is available), but it is most strongly associated with her own body size. In other words, the bigger the female, the more babies she can have!

Speaking of bigger, female Northern Water Snakes are quite a bit bigger than males in this species. The maximum body size reported in Conant and Collins for a Northern Water Snakes was 1500 mm (almost 5 feet).

What should I do if I find a Northern Water Snake?

Look, but don’t touch! Even though they are not venomous, water snakes are considered an aggressive species and will bite if handled. If you do pick one up and get bitten, don’t panic! Just treat the small wound like any other scrape or scratch (wash with soap, bandage if needed).


  • Conant, R. and J. T. Collins. 1998. Reptiles and Amphibians: Eastern and Central North America. Peterson Field Guides (series), 3rd ed. expanded, Houghton Mifflin Co., New York, New York, 616 pp.
  • Gibbons, J.W. and M.E. Dorcas. 2004. North American Water Snakes: A Natural History. University of Oklahoma Press, Norman. 438pp.

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Written by Rob Nelson

Rob is an ecologist from the University of Hawaii. He is the co-creator and director of Untamed Science. His goal is to create videos and content that are entertaining, accurate, and educational. When he's not making science content, he races whitewater kayaks and works on Stone Age Man.

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