Snake Jaws

Top Photo: Northern water snake.

Northern water snake (nerodia sipedon) is the water snake of the North Carolina Piedmont. The banded and brown water snake look-a-likes are more closely tied to the coastal plain.

The water snake shown here was basking on a wax myrtle branch next to the floating walkway in our wetlands. Curiously, this snake kept opening and closing it’s mouth. This is probably the same snake I reported seeing on May 26 which also kept opening and closing its mouth. Other rangers have reporting seeing this snake and confirming the behavior.

Snake repeatedly opened its mouth.

A little research showed that this behavior is sometimes associated with a respiratory problem, an imminent molt, or the resetting or realignment of its jaw after eating large prey.

Apart from the opening and closing of the mouth, it’s behavior was noted as normal by myself and other observers. There’s no way, other than capturing the snake, to see if it was ill in some way, respiratorily or not.

Otherwise normal behavior.

Cloudy, opaque eyes are a good indication of a molt at hand. Though the body of the snake was rather dull, it’s eyes were clear. I don’t think it was about to molt.

Clear eyes.

The snake was rather wide-bodied, but even so it did seem to have a bulge as if prey was inside. The following picture shows that. Though, it may simply be that the body is contacting the branch at that point compressing it and pushing the sides out, making it look wider.

Note bulge at circle.

My best guess is the snake somehow suffered an injury to its jaw. While watching the snake, It not only opened wide but moved the jaw from side to side. The snake has been doing this for several days, according to observer reports.

Here, snake moves jaw from left to right, and back.

It does appear as if the snake is trying to realign something in its jaw. Could it have done permanent damage to itself by eating very large prey? Does it sometimes take days to recover from an especially large meal? Or did it have an encounter with a rival? I see no other marks on the snake, so that’s not likely.

The snake was seen again on June 1, lying in wait for the numerous freshly-morphed bullfrogs in the area. The behavior was the same as previous encounters, constant gaping and side-to-side movements to the jaw. There was, though, a red mark in the corner of the snake’s mouth. If the mark is blood, it could be from a prey item, one of the many frogs the snake was hunting.

Note red mark in corner of mouth (6.1.23).

I’ll keep an eye out for this snake and report back my observations.


Nerodia sipedon is the only water snake in our wetlands. It’s non-venomous. We don’t have cottonmouths here, and the copperhead, which IS venomous, prefers dryer habitats (we DO have copperheads on the campus).

For more on these snakes visit Water Snake vs Copperhead and More Snakes.

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