The Carlisle Mosquito Online

Friday, June 4, 2004


Northern Water Snake

The snake (left), partially covered by leaves, grasps a catfish in the belly with hopes of a hearty meal in the offing.
Name: Northern Water Snake or Nerodia sipedon. The genus name is made from the Greek words 'neros' for flowing and 'dia' for through. It is a member of the largest family of snakes, the Colubrids.

When and where seen: On May 29, Tom and D'Ann Brownrigg were showing me a bee tree at Great Brook Farm State Park. While there, we decided to go and look at the other hive in the old red building beside the pond. While there, we noticed across the pond what looked like a fish trying to climb the bank. Closer investigation showed a relatively large catfish firmly in the jaws of a water snake which seemed to be trying to push it out of the water. Water snakes are quite common around bodies of water in Massachusetts. You are most likely to see one basking near beaver dams and lodges, bridge abutments, or anywhere in the vegetation close to the water's edge. I have seen them at the Maple Street bridge and at other places in Great Brook Farm State Park.

Distinguishing characteristics: Markings on the northern water snake vary a lot. Younger ones typically have repeating bands, saddles, or splotches of red or reddish-brown. These patterns are much less obvious as the snake gets older and it becomes almost uniformly dark or a dull black. The scales are strongly keeled and you can see the texture from several feet away. It is a thick-bodied snake. The one we saw (with the catfish) was about three feet long and two or three times the stoutness of a garter snake of the same length.

Food: Water snakes eat mainly fish, frogs, tadpoles, and salamanders but will also take small mammals, birds, insects and other invertebrates. The water snake is not venomous. It is not a constrictor. It swallows its prey whole and usually alive. The catfish was going to present a challenge because it was very large. The snake had its fangs in the belly of the fish, and for the 15 to 20 minutes that we watched it showed no signs of trying to maneuver the fish into a position for swallowing.

Reputation: I found numerous warnings that the water snake is very likely to bite if it feels cornered or you try to pick it up. One writer felt that the snake was getting a bad rap and that other creatures like chipmunks or bluejays were equally likely to bite if captured. If the water snake is threatened but not cornered, it will retreat to the water. If you come upon a water snake that flattens itself out into a ribbon-like form, it would be a good idea to retreat yourself. This flattening behavior is usually associated with striking and biting.

References: Leo P. Kenney and Matthew R. Burne, Field Guide to the Animals of Vernal Pools; UMass Guide to Massachusetts Snakes at

Submissions for the Biodiversity Corner are encouraged from everyone. Send in your ideas, your photos, your sightings, or write the whole column and send to Kay Fairweather at 392 School St, Carlisle MA 01741 or to

2004 The Carlisle Mosquito