Critter Corner No. 8 – The Common Water Snake by George Sly

With the beginning of fall, and the anticipation of the frosty weather to come, this edition of Critter Corner is devoted to a common denizen of the Goose Pond wetlands who will soon enter its long winter nap. Normally by late October we will have seen the last of the Common Water Snake until its emergence from hibernation in late March or April. In Indiana, Nerodia sipedon is by far the most common water-dwelling snake. Practically any body of water may serve as habitat for this species but they seem to prefer aquatic habitats that are shallow, relatively warm, and with little or no current.

Common water snakes are frequently seen basking on logs, stumps, overhanging branches, or sometimes even on the banks of ponds and marshes. They seem to have some degree of curiosity as I have had them approach me while fishing from a shoreline. One of my childhood memories of first encountering this species was glancing down to check my stringer of bluegills and seeing a Nerodia lying there peering up at me. As an adult with a great fondness for snakes, I’m mortified to report that this first chance meeting saw me take to my heels in terrified flight. Left behind was the stringer of fish and my tackle. Of course, at my first movement, the water snake hightailed it in the opposite direction and was nowhere to be seen when I rather shamefully crept back to retrieve my possessions.

This brief story does illustrate the fact that a good many people, even as adults, possess a rather unreasonable fear of the common water snake. As a retired biologist, I can’t recall the number of times people would report seeing one of these snakes while fishing or otherwise being around the water. Invariably they would refer to this animal not as a common water snake but as a “water moccasin”. Despite my assurances that what they had seen was not an example of that highly venomous species, I had the feeling that my explanations were often falling on deaf ears. There are two points to be made here. First, this confusion is a really good example of why biologists generally prefer scientific names over common names. As most of you probably know, each species of organism has its own scientific name. Such names are generally derived from Latin or Greek. They are comprised of the Genus name (in this case Nerodia, referring to the snake’s habits) and the specific name (here it is sipedon, which refers to its bite). A common name on the other hand may refer to different organisms. These two snakes are an example. Sometimes a common name is used for totally different animals. The term gopher may bring to mind a turtle in Florida, a true pocket gopher in Illinois, or a ground squirrel in Indiana. Sometimes common names can mislead; a starfish or a jellyfish is not really a fish. So, to make a long story short, folks living within the range of Nerodia sipedon often simply use the common moniker of “water moccasin” for this species.

A second reason that the common water snake is often mistaken for a true water moccasin, or cottonmouth, is that they do indeed look quite a lot alike. Incidentally, the western cottonmouth (Agkistrodon piscivorus) does actually occur in Indiana. In 1983 a relic population of this snake was found in Dubois County. The cottonmouth is listed as an Endangered Species in Indiana. There are, of course, significant differences in the anatomy of common water snakes and the cottonmouth. The differences are such that they are placed into different families (Colubridae and Viperidae). Think of it as being like separating carnivores into the cat family and the dog family. Nevertheless, many of the water snake species bear a strong resemblance to the cottonmouth in terms of coloration, stocky build, and habitat preference.

Another story might illustrate how much alike they really can look at times. My wife and I had the opportunity a few years ago to canoe the Wekiva River in central Florida. She sat in the bow; I was at the stern. It was a beautiful stream which quietly flowed through forests of cypress and gum and we leisurely paddled our way along attentive to any animals we might spot. As we rounded a bend, I saw a fallen tree whose barren branches hung out over the stream. In the top of this tree, some ten feet above the water, basked a good sized snake. The large heavy build, broad head, and distinct dark cross-bands on a brownish body fairly shouted cottonmouth to me. Urging Anne to help me paddle closer, I continued looking upward at the somnolent snake. Now, the closer I got, the less sure I became of my identification. I asked Anne to help me move a little nearer. Now, in close proximity to the snake, I became convinced that it was after all simply a Nerodia species of some sort. If only I could get a little nearer I could be certain. Suddenly I became aware that in spite of my strong paddling I was making no headway in getting closer to my quarry. It was then that I looked to the bow of the canoe to see Anne furiously beating the water to froth. I had inadvertently put her into a position whereby the snake in question loomed ominously right over her head. The turbulent flow issuing from her paddle would have done the old stern-wheeler Mississippi Queen proud. Needless to say I got no nearer the serpent but by now it had indeed resolved itself into a brown water snake. No big deal.

As one would expect of such a highly aquatic snake, their diet consists of fish of assorted kinds including various minnows and catfish. Common water snakes have little impact on game fish populations. They will also eat frogs and toads, their tadpoles, and salamanders. Water snakes are ovoviviparous which essentially means that females retain their eggs internally until the yolk-fed young are born alive. The number of offspring in a litter may be several dozen but the average seems to be around eight. Water snakes of all kinds do of course have their own predators. Large fish, such as bass, as well as wetland birds such as herons will take them. Marshland mammals including raccoons and mink will also prey on snakes. Juvenile water snakes may even fall victim to bullfrogs.
It is best to enjoy a chance meeting with the common water snake from a distance. Although non-venomous and essentially harmless, they do have a nasty disposition. Given a chance they will flee but cornering or trying to handle them seems to bring out their dark side. In such cases, they will bite fiercely and often.

Common water snakes, by acting alternatively as predator and prey, serve as an important cog in the complex ecological machinery of the wetland. Oh, and one more thing. Let’s not call them water moccasins.

For those with further interest in Indiana snakes, I recommend:
Conant, Roger and Joseph T. Collins. 1998. Reptiles and Amphibians: Eastern/Central North America. Peterson Field Guides. Houghton Mifflin Co. New York.

MacGowan, Brian and Bruce Kingsbury. Snakes of Indiana. IUPUI Fort Wayne and IDNR, Division of Fish and Game. Indianapolis.

Minton, Sherman A. 2001. Amphibians & Reptiles of Indiana. Indiana Academy of Sciences. Indianapolis.