Common watersnake

Northern water snake
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Colubridae
Subfamily:	Natricinae
Genus:	Nerodia
Species:	N. sipedon
Binomial name
Nerodia sipedon (Linnaeus, 1758)
Subspecies
4, see text
Synonyms
Coluber sipedon Linnaeus, 1758 Tropidonotus sipedon Holbrook, 1842 Natrix sipedon Stejneger & Barbour, 1917

The Northern water snake (Nerodia sipedon) is a large, nonvenomous, well-known snake in the Colubridae family that is native to North America.

Behavior

Northern water snake west of Ottawa, Ontario

They are active during the day and at night. They are most often seen basking on rocks, stumps, or brush. During the day, they hunt among plants at the water's edge, looking for small fish, frogs, worms, leeches, crayfish, salamanders, small birds and mammals. At night, they concentrate on minnows and other small fish sleeping in shallow water. The Lake Erie water snake subspecies, Nerodia sipedon insularum, was once endangered, but now benefits from the introduction of the round goby, an invasive species, which now comprises up to 90 per cent of its diet.

Subspecies

Ordered alphabetically.

• N. s. insularum – Lake Erie water snake
• N. s. pleuralis – Midland water snake
• N. s. sipedon – Northern water snake
• N. s. williamengelsi – Carolina water snake

Description

The Northern water snake can grow up to 135 cm (4.4 ft) long. They can be brown, gray, reddish, or brownish-black. They have dark crossbands on their necks and dark stripes and blotches on the rest of their bodies, often leading to misidentification as cottonmouths or copperheads by novices. They darken as they age. Some will become almost completely black. The belly of this snake also varies in color. It can be white, yellow, or gray. Usually it also has reddish or black crescents.

Reproduction

Northern water snakes mate from April through June. They are ovoviviparous (live-bearers), which means they do not lay eggs like many other snakes. Instead, the mother carries the eggs inside her body and gives birth to free living young, each one 19–23 cm (7.5–9.1 in) long. A female may have as many as thirty young at a time. They are born between August and October. Mothers do not care for their young; as soon as they are born, they are on their own.

Defense against predators

Northern water snakes have many predators, including birds, raccoons, opossums, foxes, snapping turtles, and other snakes. They defend themselves vigorously when they are threatened. If they are picked up by an animal, or person, they will bite repeatedly, as well as release excrement and musk. Their saliva contains a mild anticoagulant, which can cause the bite to bleed more but poses little risk to humans.

Hibernation

Northern water snakes often share winter dens with copperheads and black rat snakes.

Habitats

Muskrat houses and beaver lodges are good places to find water snakes, which like to hide among the sticks and plant stems. They live near lakes, ponds, marshes, rivers, and canals; just about anywhere there is freshwater.

The Lake Erie water snake subspecies (Nerodia sipedon insularum), which occurs mainly on the lake's western islands offshore from Ohio and Ontario, recovered to the point where on August 16, 2011 the U.S. Fish and Wildlife Service removed it from the Federal List of Endangered and Threatened Wildlife. The subspecies was first listed as threatened in 1999 after a decline due to eradication by humans, as well as habitat loss and degradation. When initially listed, the subspecies’ population had dropped to only 1,500 adults. Endangered Species Act (ESA) protections for the snake included designation of 300 acres of inland habitat and 11 miles of shoreline for breeding grounds. Ironically, the introduction of an invasive species, the Eurasian Round goby (Neogobius melanostomus) into Lake Erie in the mid-1990s became a new food source for the Lake Erie water snake. By 2009, the population recovered to 11,980 snakes, safely exceeding the population minimum goal of 5,555 adult snakes required by the 2003 recovery plan. Monitoring will occur for 5 years following this delisting. The Lake Erie water snake is just the 23rd species to be removed from the list due to recovery.

Gallery

• 
  Nerodia sipedon swimming in the Chesapeake Bay in the United States
• 
  Nerodia sipedon swimming in the Potomac at Harpers Ferry in the United States
• 
  Mature Northern water snake sunning itself near Battersea, Ontario in Canada
• 
  Preparing to moult, Prince Edward County, Ontario
• 
  Hunting on beach near Georgian Bay, Ontario

External links

• Snakes, Davidson College
• Northern Water Snake, Species account on eNature
• Northern Water Snake, Species account from the Iowa Reptile and Amphibian Field Guide
• Northern Water Snake, Natural Resources Canada
• for information on northern water snake control