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BROWN SNAKE

Storeria dekayi


BROWN SNAKEDescription: This is a very small brown, grayish brown, or tan snake with two parallel rows of dark spots down the back. The spots may be connected across the back by dark crossbars, forming a ladderlike pattern; occasionally the spots are faint or entirely lacking (see the following note on subspecies differences). The area between the dorsal spots is usually lighter in color than the sides, giving the impression of a single wide dorsal stripe. Some individuals have scattered dark spots along the sides. The head is small and dark above; there is often a vertical dark bar at the back of the jawline, a dark spot (sometimes two) beneath the eye, and a dark blotch on each side of the neck. The belly varies in color from cream to buff or light pink, and there may be small dark dots at the edges of the ventral scutes. There are usually 17 scale rows at midbody; the scales are keeled and the anal plate is divided. Total adult length: 23 to 52.7 cm (9 to 20.7 in); very few Brown Snakes exceed a length of 38 cm (15 in).

Males are slightly smaller, on average, than females and have relatively longer tails; the male's tail is usually 23 percent to 26 percenT of total length (subcaudal scutes number 46 to.73), and the female's tail is 17 percent to 23 percent of total length (with 36 to 66 subcaudals). The newborn young measure 7 to 11.7 cm (2.7 tq 4.6 in) in length and are darker than their parents, but with a light band or "collar" around the neck.

Note: Two subspecies of the Brown Snake meet in the Great Lakes region. The Northern Brown Snake (Storeria dekayi dekayi) enters our area from the east. This form typically has few or no dark crossbars linking the dorsal spots across the back. The Midland Brown Snake (Storeria d. wrightorum), the dominant form from the Lake Michigan basin southward along the Mississippi drainage, has numerous crossbars linking the dorsal spots. A third subspecies, the Texas Brown Snake (S. d. texana) approaches the Great Lakes area in central and western Wisconsin. It has thin dorsal crossbars and a conspicuous dark blotch on each side of the neck. The first two subspecies intergrade broadly over the region from southern Ontario through Ohio and Michigan's Lower Peninsula; in this area the assignment of a particular Brown Snake to one subspecies or the other will be often be difficult or impossible, and (except for taxonomic studies) unnecessary.

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Confusing Species: Northern Red-bellied Snakes usually have red or pink bellies and 15 scale rows at midbody. Garter snakes have light stripes along the sides and a single anal plate. Northern Ring-necked Snakes lack spots or stripes on the back and have yellow or orange bellies and smooth scales.


Map of Brown Snake's distribution in Michigan.Distribution and Status: This species ranges from southern Maine, Quebec, and Ontario to Florida and the Gulf Coast and west to Minnesota, eastern Nebraska, Kansas, Oklahoma, and eastern Texas southward into Mexico and Honduras. It occurs throughout the Great Lakes region except for the area north of Georgian Bay and Lake Superior; it is sparsely distributed in northern Wisconsin and Michigan's Upper Peninsula. Brown Snakes are locally common but become considerably less common toward the northern periphery of their range.

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Habitat and Ecology: Brown Snakes occur in a great variety of habitats, from dense woods and shrublands to open prairies, meadows, and marshes. Moist soils are preferred, but they are sometimes found on dry hillsides, railroad embankments, and in pine woods. This species is tolerant of human-modified habitats and can be common in agricultural, urban, and suburban areas, particularly in weedy fields and dump sites strewn with sheltering debris such as boards, bricks, tar paper, sheet metal, or cardboard.

BROWN SNAKEThese secretive little snakes spend much of their active season below ground or under leaf litter or surface debris, although a heavy rain will sometimes induce them to move about in the open. Brown Snakes are largely nocturnal, especially in summer. Most surface activity occurs in fall (October and November) and in early spring (late March and April), when they are moving to or away from hibernation sites. They overwinter in animal burrows and abandoned anthills, beneath stumps and logs, and in crevices in rock ledges and house and barn foundations. Individual Brown Snakes typically return to the same hibernacula used the previous winter, sites often shared with other small snake species such as various garter, Red-bellied; and Smooth Green Snakes.

Earthworms and slugs form the greatest part of the diet, although snails, pill bugs, soft-bodied insects, and small amphibians are also eaten on occasion. Brown Snakes have specializations of the jaws and teeth that assist them in pulling snails from their shells. Since most prey is taken underground and/or at night, it is likely that food is located largely by use of the tongue and vomeronasal organ.

Brown Snakes are readily eaten by a host of predators, including large frogs and toads, larger snakes, crows, hawks, shrews, weasels, and domestic cats and dogs. Ground-feeding birds that sift through leaf litter, such as jays, thrushes, and thrashers, probably take many of these snakes. This is a docile species that rarely attempts to bite; in any case the tiny teeth would be an ineffective defense against most enemies. When cornered or seized a Brown Snake may flatten its body and assume a threatening posture and often releases a musky fluid from the cloaca.

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Reproduction and Growth: Courtship and mating occur in early spring, with the males undoubtedly taking advantage of the presence of females prior to dispersal away from group hibernacula. The male locates a potential mate by following a pheromone (odor) trail left by the female. The female is approached and identified with numerous tongue-flicks; the male then moves over or alongside the female, aligning his body with hers. The male attempts to keep his chin on the female's neck and align his cloacal region with that of the female; at this point a succession of ripplelike movements may travel up the male's body, from tail to head. Eventually the male inserts a hemipenis into the female's cloaca to effect fertilization. Sometimes two or more males may court the same female; they may engage in mild shoving to gain the best position, but there is no actual fighting among the rivals.

Most females give birth to their litters in late July or August (range, late june through September). Litter size ranges from 3 to 41, but 10 to 14 young is most typical. There is no parental care, but newborn Brown Snakes often remain in close association for some time after birth. Growth can be rapid, and some young Brown Snakes will nearLy double in length by the end of their second summer, when they are probably sexually mature. A captive Brown Snake lived over seven years in captivity.

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Conservation: Despite their local abundance in.the less intensively developed city parks and residential areas, these secretive snakes often remain undetected (and unappreciated) by their human neighbors. Brown Snake colonies in urban and agricultural settings are in constant danger of rapid extirpation by development activities or exposure to toxic chemicals. They are harmless to human interests and may help control slug damage in gardens. These interesting little snakes are worthy of consideration in urban and suburban park and open-space conservation planning efforts.

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The above information has been reproduced or complied from the field guides with permission to use such material from the author, James Harding, for the sole use of educating the public on native Reptiles and Amphibians. The field guides used were:

  • Michigan Snakes: A Field Guide and Pocket Reference (1989; rev. 1998) by J.A. Holman, J.H. Harding, M.M. Hensley, and G.R. Dudderar, Michigan State University Cooperative Extension Service, East Lansing, E-2000.
  • Amphibians and Reptiles of the Great Lakes Region by J.H. Harding, (2000) University of Michigan Press, Ann Arbor.

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