The Carlisle Mosquito Online

Friday, November 17, 2006


(Photo by Tom Brownrigg)

Biodiversity Corner - Northern Brown Snake (Storeria dekayi)

On September 30, my wife D'Ann and I walked the Greenough Land trail that starts just north of the Maple Street bridge and continues to Greenough Pond. On the way back, D'Ann noticed a small snake, dead along the side of the road near the trail entrance. The snake was about 14 inches long, and about 3/8 inch wide at its maximum width. It was brown above with a darker dorsal stripe, and slightly salmon pink underneath. We had never seen a snake like this in Carlisle, where we have lived for nearly 35 years. Although the snake was dead but not badly mangled, I took several photos hoping that we could identify it later.

The quest for identification

After consulting various books, I decided that it was probably either a Northern Brown Snake or the Northern Redbelly Snake, although it did not exactly match the description of either species. Subsequently, I met Misty-Anne Marold of the state's Natural Heritage and Endangered Species Program (NHESP) at a meeting in Concord, and she agreed to look at the photos. I had previously also sent the photos to Dr. Scott Jackson of the UMass (Amherst) Extension; Dr. Jackson is a co-author of the extension's snake guide (1). Both independently identified the snake as the Northern Brown Snake. The Redbelly Snake, also found in our area, has a distinctively reddish belly and several large white patches behind the head.

The Brown Snake was formerly called "DeKay's snake," named after early New York naturalist James DeKay. Conant (2) writes, "This could almost be called the 'city snake' because of the frequency with which it turns up in parks, cemeteries, and beneath trash in empty lots, even in our largest urban areas. Despite its abundance, it is so adept at hiding that few persons know it, and those that encounter it for the first time mistake it for a baby Garter Snake." Outside of urban areas, the reclusive Brown Snake inhabits freshwater marshes, moist woods and hillsides, habitats similar to the Greenough Woods where we found it.

Brown Snake's coloring

The Brown Snake is dark brown to grayish brown above, and light yellow, brown, or pinkish underneath. On the back, there are two rows of dark spots bordering a lighter central area. It also has a dark inverted V-shaped patch under the eye and near the mouth, a field mark better seen in photographs of Vermont's snakes (3).

Brown Snakes go into hibernation for the winter by November in Massachusetts, and mate in the spring. Typically, 8 to 20 young are born alive from mid-July through August. The preferred foods are earthworms and slugs (gardeners take note!), although they will also eat sow bugs, insects, spiders, and small fish, frogs and toads. They are active during the daytime in the spring and fall, but are largely nocturnal during summer (1).

The writer thanks Misty-Anne Marold and Dr. Scott Jackson for their help with identification.


1. S. Jackson & P. Mirick, Massachusetts Snakes: A Guide, U. Mass. Extension & Mass. Div. Fisheries & Wildlife; available at

2. R.Conant, A Field Guide to Reptiles and Amphibians, Houghton Mifflin Co., 1958.

3. Sandgate, Vermont's 11 snake species at

Submissions and ideas for the Biodiversity Corner are encouraged on any wildlife in town. Send a note to Kay Fairweather at 392 School Street, Carlisle, MA 01741 or to

2006 The Carlisle Mosquito