Northern Water Snake

Overview:

Scientific Name: Nerodia sipedon sipedon
Size: 24 – 55.3” (total adult length)
Status: Can be common to abundant, but many local populations have suffered declines or extirpation due to pollution or direct attack by fearful humans.

Habitat:

Occupies permanent bodies of water such as rivers, streams, sloughs, lakes, ponds, bogs, marshes, swamps, and impoundments. Open, sunny areas with available cover and basking sites are preferred habitat.

Adult Coloration:

Tan, brown, or gray background color with a varied pattern of black, dark brown, or reddish brown crossbands and blotches on back and sides. Crossbands are generally complete on the front third of body, while toward the tail there are often alternating dark saddles and side blotches. Dark pigment may obscure the pattern in older Northern Water Snakes, which may appear solid brown or black. Belly is white, yellowish, or orangish, with a pattern of reddish brown half-moon marks, sometimes with grayish or brownish speckling between.

Adult Characteristics:

Moderately large snake with keeled scales (each scale has a small central ridge) and a divided anal plate. Males are smaller than females on average and have longer tail

Juvenile Characteristics:

Newborns may be 7.5 – 10.6” in length and are more distinctly patterned than adults with black or reddish brown bands and blotches on a gray or tan background.

Scale Count:

21 to 25 scale rows at midbody

Species Confused With:

The Copper-bellied Water Snake is similar but has a plain red or orange belly, sometimes with dark brown or black along the edges. Kirtland’s Snake has a pink or red belly with black spots in rows down each side. Garter and ribbon snakes have lengthwise stripes down the back and an undivided anal plate. The Eastern Milk Snake has a black and white checkerboard pattern on the belly, smooth (unkeeled) scales, and a single anal plate.

References:

• Amphibians and Reptiles of the Great Lakes Region by Jim Harding
• Harding, J.H. and J.A. Holman. 2006. Michigan Snakes. MSU Extension Ext. Bulletin E-2000,74 pp. [revised].
• Ruthven, A. G., H. B. T. Gaige, et al. 1912. The herpetology of Michigan, by Alexander B. Ruthven. Crystal Thompson and Helen Thompson; Memoranda towards a bibliography of the archaeology of Michigan, by Harlan I. Smith; prepared under the direction of Alexander G. Ruthven. Lansing, Mich., Wynkoop Hallenbeck Crawford, State Printers.
• Holman, J. A. 2012. The Amphibians and Reptiles of Michigan: A Quaternary and Recent Faunal Adventure. Detroit, Mich., Wayne State University Press.
• Conant, R., and Collins, J. T. 1998. Reptiles and Amphibians: Eastern, Central North America. Houghton Mifflin Harcourt Press.