General Description: The Northern Watersnake is a moderately-long, robust snake, with adults ranging from 27–32 inches (68.6–81.3 cm) in length. The background coloration is dark brown or gray and individuals often have a series of reddish-brown to copper colored markings bordered in black down the length of the entire body. Towards the head, these markings form bands, but as at midbody and towards the tail, these markings separate and form separate dorsal and lateral blotches. As juveniles, this patterning is present, though the background coloration and blotches may be lighter in appearance. Patterning often fades in older individuals. Scales on this species are heavily keeled, giving individuals a rough texture. The belly is often heavily patterned with copper or rust colored crescent-shaped markings that are outlined in black.
Behavior: Northern Watersnakes are a nocturnal species, but can spend large parts of the day basking along shorelines or in vegetation overhanging the water. This species is a generalist predator, though primarily consumes fish and amphibians. Upon capture, this species is likely to bite and release a foul-smelling musk.
Reproduction: Mating often takes place in late April when individuals have emerged from hibernation. Similar to gartersnakes, multiple males may attempt to court a single female. Females have an average of 26 young which are born live, typically in August or September.
Habitat: The Northern Watersnake can primarily be found in close associated with permanent ponds, lakes, streams though they can be found in temporary aquatic habitats (i.e., flooded fields) as well.
Species Range: This species can be found across much of the eastern United States and into southern Canada, the Great Lakes Region, and along the Mississippi River to its confluence with the Gulf of Mexico.
South Dakota Range: Northern Watersnakes are likely South Dakota’s second rarest snake and have only been found in a small area near Springfield, South Dakota and the Missouri River Delta (upper Lewis and Clark Lake).
South Dakota Status: This species is monitored by the South Dakota Natural Heritage Program. Any sightings of this species should be reported to South Dakota Game, Fish and Parks (report observation).
Account written by Drew R. Davis