Water Snakes (Nerodia spp.) belong to a family of non-venomous colubrid snakes found in North America. In the south-eastern USA, Water Snakes are among the most abundant and most often encountered reptiles. Although they are not venomous they will defend themselves and bite if threatened. Water snakes are known to display aggressive behavior.
Water Snakes can climb and they are often found resting on branches above the water. When disturbed they will drop into the water - sometimes into boats passing by.
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Water Snakes commonly forage in the water's edge looking for small fish - preferably the slow moving fish (Linzey & Clifford, 2002)1 - and other animals in the shallow water. They eat small fish, reptiles, frogs, worms and small birds and mammals. All Water Snakes eat their prey alive. Until Water Snakes reach a certain size their main prey are small fish and other small animals found in the water. Water Snakes that belong to other groups than Nerodia are not described here. Frogs and birds are captured by larger individuals. According to a study2 (Mushinsky et al. 1982) there is a shift in prey choice towards frogs and other larger animals when the snakes reach a length of about 1.5 feet. However, a water snake less than 1.5 feet will probably not eat many frogs or other larger animals (ibid). |
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Diet
The diet of Water Snakes is primarily composed of fish, but frogs, salamanders and frog tadpoles are also commonly found in stomachs of water snakes upon dissection. A study by King (1939)3 showed that 35% of a population of water snakes had tadpoles and salamanders in their stomachs, besides all other types of prey.
Sexual dimorphism
Females are significantly heavier and larger than males. They also grow considerably faster than males.
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A full table of this type can be found as a pdf here. |
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Hunting in water
Water Snakes dwell in shallow waters with its mouth open waiting for any prey to come close by - within a few inches - so it can close its jaws around the prey. It also moves around on the underwater surface looking for prey in rock crevices and other hiding places (Drummond, 1983)4. Water Snakes hunt both day and night.
They have a compound in their saliva inhibiting coagulation of blood. The advantage from having an anti-clotting compound in its saliva is that when prey escapes it will leave a trail of blood that the water snake can follow.
Life-cycle of water snakes
Water snakes mature when they are 3 to 4 years old5. Mating takes place in the spring and snakes are born between August and October. Often many male snakes are courting one female snake. Water snakes give birth to live snakes. The eggs hatch within the female body before the birth. Litters of about 20 snakes are common and the newborn snakes have a length of 8-12 inches on average.
Northern Water Snake
The Northern Water Snake (Nerodia sipedon) is found in many different types of freshwater habitats. It can be found near large rivers and small ponds as well. When conditions are good these snakes can be found in very high numbers. This type of snake is a relatively large snake with adult females reaching a length of almost 5 feet.
They can reach an age of approx. 7-8 years. Their litters have a size of anywhere from 10 to 40 snakes and new snakes are born during late summer and early fall. The snakes mainly feed on fish, which constitute approximately 50% of the snakes's varied diet. Larger individuals also eat a lot of frogs while smaller individuals eat anything from invertebrates to small mammals.
Because of its vicious temperament, the Northern water snake, as well as other water snakes, are not suitable for keeping as pets. As the Northern Water Snake is fairly common and share some similarities with the venomous cottonmouth snake, many are killed on the suspicion on being cottonmouths.
Water snakes also have scent glands near the base of their tails (in their cloaca) from which they can excrete an ill smelling musk in the case they feel threatened.
References
1 Linzey, D.W., Clifford, M.J., Snakes of Virginia (2002)
2 Mushinsky, H.R., Hebrard, J.J., Vodopic, D.S. Ontogeny of Water Snake Foraging Ecology.
Ecology, 63(6) pp. 1624-1629 (1982)
3 King, W., A survey of the herpetology of the Great Smoky Mountains National Park, Amer. Midi. Nat. 21, pp. 531-582 (1939)
4 Drummond, H., Aquatic Foraging in Garter Snakes: A Comparison of Specialists and Generalists, Behaviour, Vol. 86 (1/2) pp. 1-30 (1983).
5 Brown, G.P. and Weatherhead, P.J., Thermal Ecology and Sexual Size Dimorphism in Northern Water Snakes, Nerodia sipedon Ecological Monographs, 70(2), pp. 311-330 (2000).
Web links ↓
Confronting Water Snakes
A nature bulletin
Connecticut River W.S.
Concho W.S.
Southwestern Herp
European Snake Society
Virginia Herpetological Society
Contact information”
Acknowledgements
Thanks to Benny, Patrick, Charles, Jacob, Maria, Lisa and Alan for giving me the permission to use their photos.