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Northern Watersnake

Northern watersnake © Joe Crowley


Northern watersnakes (Nerodia sipedon sipedon) are brown or dark brown with faint alternating dark (sometimes reddish) horizontal banding on the back and sides. Young snakes are greyish with pronounced brown banding, and they become darker as they age until the patterning can barely be seen. The belly is lighter in colour, often white or tan with dark red, tan or brown crescent-shaped spots. The scales of this species are keeled (ridged down the centre), which gives the snake a rough, rather than a shiny, appearance. Adults generally reach a length of between 60 and 110 centimetres, but some individuals may be even larger. The northern watersnake is a subspecies of the common watersnake (N. sipedon). The Lake Erie watersnake (N. s. insularum) is also a subspecies of the common watersnake but is found only on islands in western Lake Erie and on its southern shore in Ohio.

Northern watersnake © Dax

Similar Species

The northern watersnake may be confused with the gray ratsnake, eastern foxsnake, milksnake, eastern hog-nosed snake, eastern Massasauga and Lake Erie watersnake. The gray ratsnake is black with faint blotches, whereas the northern watersnake is dark brown with faint banding. The eastern foxsnake has a yellow to light brown body with brown blotches down its back and two alternating rows of smaller blotches along the sides. The milksnake has red or reddish brown blotches along its back and sides with a distinct black outline around each blotch. The eastern hog-nosed snake has a distinct upturned snout. The eastern Massasauga has a rattle on a blunt tail, a vertical pupil and a triangular head. Distinguishing northern watersnakes from many Lake Erie watersnakes is almost impossible, but their ranges do not overlap. Lake Erie watersnakes are found only on islands in western Lake Erie, including Pelee Island, whereas northern watersnakes are not present on those islands.

Northern watersnake © Joe Crowley


The northern watersnake can be found in and around almost any permanent body of fresh water within its range, including lakes, rivers and wetlands. Rarely far from shoreline habitats, these snakes can be found in shoreline vegetation, basking on rocks and logs, or in other open habitats along the edges of the water or under rocks along the shoreline. Northern watersnakes hibernate underground in dens or crevices, or in beaver lodges.

View an interactive map of the known ranges of northern watersnakes in Ontario.


Northern watersnakes breed in the spring after emerging from hibernation. Females develop the eggs within their bodies and give birth to live young in late summer or early autumn. In Ontario, females give birth to five to 37 young. Often a clutch of hatchlings has more than one father. The size of the hatchlings is related to the mother’s size but averages about 16 centimetres. In Canada, these snakes reach maturity in three to four years.

The northern watersnake eats fish and amphibians, hunting for its prey along the water’s edge or underwater. It is an excellent swimmer and can be found up to three metres below the surface of the water and several kilometres from shore. Although this snake usually swallows small prey head first upon capture, it may carry large fish to shore before consuming them. The northern watersnake frequently basks in the open, often in large groups.

This species is active in the day and at night. Like the Lake Erie watersnake, the northern watersnake is curious and not as wary of humans as many other snakes are. It may even approach swimmers as it investigates the source of ripples in the water (which could be from a fish or other prey) or if it mistakes them for a floating log or other debris it can hide in or bask on. Northern watersnakes are harmless but will bite in self-defence if they are captured. Although often their bite is not even felt, it can cause mild bleeding because the snake’s saliva contains an anticoagulant.

Other names: watersnake, Natrix sipedon sipedon 

Juvenile northern watersnake © Joe Crowley

Threats and Trends

The northern watersnake is widespread and abundant within its range in Canada and is one of the most commonly seen snakes around lakes. There are few threats to this species, but waterfront construction and development, as well as water pollution, affect both its habitat and food sources. Habitat loss, road mortality and persecution by humans also negatively affect the northern watersnake.

Northern watersnake © Peter Ferguson

Current Status and Protection

The northern watersnake was assessed as Not at Risk by the Committee on the Status of Endangered Wildlife in Canada in 2002, but has not been assessed by the Committee on the Status of Species at Risk in Ontario. This species has no status under the Endangered Species Act, 2007, or the federal Species at Risk Act. The species has been designated as a Specially Protected Reptile under the Ontario Fish and Wildlife Conservation Act, which offers some protection to individuals and their habitat. The International Union for Conservation of Nature has not yet assessed the global status of the northern watersnake, but lists the common watersnake (of which the northern watersnake is a subspecies) as Least Concern. The common watersnake’s status was last confirmed March 2007.

Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Amphibian Stewardship page.

Northern watersnake © Sterling Sztricsko

What You Can Do

Northern watersnake © Ken Morrison