Sunday, May 29, 2016

Northern water snake

Not a water moccasin. The northern water snake (Nerodia sipedon), while it can be an aggressive biter if provoked, is a non-venomous snake, and I was delighted to see several on a recent outing. Jess was somewhat less thrilled, especially since the first one took her quite by surprise as we were watching bluegills and green sunfish maintain and defend their nests at the edge of a pond. Nevertheless, she recovered nicely and took many of the photographs here.

Northern water snakes are, obviously, strong swimmers. When hunting, they tend to cruise the water immediately adjacent to the bank—hence Jessica's sudden alarm. They are apt to head for open water when themselves startled, or when traveling rather than actively looking for prey.

They also hunt ambush-fashion, generally facing the bank and keeping uncannily still, either completely submerged or with head held above the surface. In this attitude, they resemble nothing so much as a stick in the water, and doubtless this is the last thing many a frog or vole doesn't see. (Camouflage was probably enhanced on this particular day by the abundance of cottonwood down floating on the water.)

We also saw the snakes immobilised on the bottom amidst the sunfish nests; whether this represented ambush hunting or merely resting, we couldn't be certain, but it was impressive how long they stayed under. Even more surprising was how little alarm this seemed to occasion among the fish, though these were probably large enough not to be in any danger.

A few more portraits of these gorgeous serpents to round things out:

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