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Northern Watersnake, Nerodia sipedon

This is the most common watersnake in Tennessee and it occurs statewide. Two subspecies are found in the state: Midland Watersnake (N. s. pleuralis), which occurs in the western two-thirds of Tennessee, and Common Watersnake (N. s. sipedon), which occurs in northeastern Tennessee.   The two subspecies interbreed where their ranges intersect.

Description: A large, heavy-bodied watersnake (24.0 to 42.0 inches in length) which has keeled scales and is highly variable in color.   Body may be grayish to brown (almost black in older specimens) with dark brown to reddish-brown crossbands on the front third of the body becoming broken into 3 rows of alternating blotches.   

Midland Watersnake has less than 30 crossbands and blotches, and the light spaces between the dark lateral markings are more than 2 ½ scale rows wide.  Common Watersnake has more than 30 crossbands and light spaces are less than 2 ½ scale rows wide. 

 Midland subspecies has a yellow belly distinctly marked with 2 rows of half moons, while the half moon markings in the Common subspecies are broken up or not clear.   Young are similar, but more boldly patterned.

Similar Species: Broad-banded Watersnake has crossbands running entire length of body and a light, black line running from the corner of the eye diagonally to the corner of the mouth. Cottonmouths are darker and more heavy-bodied with a facial pit between eye and nostril.

Habitat: This habitat generalist is found in every type of water body, but prefers quiet waters. Northern Watersnakes occur in ponds, lakes, rivers, streams, sloughs, wetlands, and temporary water pools. Frequently found around edges of ponds or lakes, basking on rocks, or on vegetation overhanging water.

Diet: Primarily feed on non-game fish; also amphibians and other small aquatic animals.

Breeding information: Males begin locating, through chemical attraction, and mating with females during the spring. Northern Watersnakes give live birth (ovoviviparous) to 5-60 young in late summer or early fall. Larger females produce more young.

Status in Tennessee: Populations are widespread and abundant. Northern Watersnakes are frequently killed by people who mistakenly think they are Cottonmouths or Copperheads. Also, they are vulnerable to polluted waters.

Fun Facts:

  • When threatened Northern Watersnakes will make a silent retreat, but are aggressive when captured. They will flatten their head and neck, try to strike and bite, and discharge a foul-smelling musk from glands at the base of their tail.

Best places to see in Tennessee: Edges of ponds, lakes, or streams anywhere in Tennessee.

Sources:

Conant, R. and Collins, J. 1998. Peterson Field Guides: Reptiles and Amphibians (Eastern/Central North America). Houghton Mifflin Company, New York. 616pp.

Jensen, J. B., Camp C. D., Gibbons, W., and Elliot, M. J. 2008. Amphibians and Reptiles of Georgia, University of Georgia Press, Athens, GA. 575pp.

Johnson, T.R. 2006. The Amphibians and Reptiles of Missouri. The Missouri Department of Conservation, Jefferson City, MO.

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Northern Watersnake Range Map