Common Watersnake
Nerodia sipedon • Colubridae (Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Nerodia, Species: N. sipedon)
Widespread across central and eastern North America, including eastern United States (from Maine south to Florida and west to Colorado) and southeastern Canada (Ontario and Quebec).
Look up Common Watersnake in the Snake Encyclopedia →Family
Colubridae (Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Nerodia, Species: N. sipedon)
Conservation
IUCN Red List status: Least Concern (LC). Stable populations across its range, though often killed by humans due to mistaken identity as the venomous Cottonmouth.
Physical Description
Dark brown, grey, or reddish-brown ground color with dark crossbands near the neck that break into alternating dorsal and lateral blotches further down the body. Strongly keeled scales give a dull texture. Head is flat and somewhat triangular when flattened defensively, with round pupils and pale labial scales with dark vertical sutures.
Size & Dimensions
Specimen appears to be a small adult or subadult around 2 to 2.5 feet (60-75 cm) in length. Typical species size ranges from 24 to 42 inches (60-107 cm), with large females occasionally reaching up to 55 inches (140 cm).
Habitat
Semi-aquatic habitats including ponds, lakes, rivers, streams, marshes, bogs, and nearby terrestrial areas. Often found under rocks, logs, or basking along water edges, retaining walls, and gravel borders.
Diet & Feeding
Active foraging and opportunistic ambush predator feeding predominantly on fish (minnows, sunfish, catfish), amphibians (frogs, toads, tadpoles, salamanders), and occasionally invertebrates or small mammals.
Reproduction
Viviparous (gives birth to live young). Mating occurs in spring (April-June), and females give birth in late summer or early fall (August-October) to litters averaging 15 to 30 live young.
Look-alikes
Frequently confused with the Northern Cottonmouth (Agkistrodon piscivorus), which is venomous. Distinguishes from Cottonmouth by having round pupils (vs. vertical slits), labial bars, lack of facial heat-sensing pits, keeled scales throughout, and alternating body blotches rather than pixelated hourglass bands.
Conservation Status
IUCN Red List status: Least Concern (LC). Stable populations across its range, though often killed by humans due to mistaken identity as the venomous Cottonmouth.
Cultural Significance
Crucial aquatic ecosystem predator that regulates fish and amphibian populations. Frequently encountered near human residences near water bodies, playing a beneficial role in local biological control.
Notable Features
Heavy-bodied aquatic colubrid with heavily keeled dorsal scales, distinctive crossbands/blotches pattern, and characteristic defensive head-flattening strategy.