Michigan Society of Herpetologists
NORTHERN RED-BELLIED SNAKE
Storeria occipitomaculata occipitomaculata
Description: This is a very small, brown, reddish brown, or gray snake with a narrow neck and small head. (In a given population the brown and gray phases may be equally common, or one phase may predominate.) The upper surface may be unmarked or have two or four thin dark stripes running down the back and/or sides; there is sometimes a suggestion of a light middorsal stripe. The top of the head is usually dark brown or red- dish brown, while the chin and throat are white. There often is a light spot behind and below the eye (on the fifth upper labial scale), and three light tan or yellow spots on the neck-one at the nape and an!:>ther on each side of the neck; these spots may fuse to form a light collar, or, alterna- tively, may be absent. As the common name implies, the belly is usually bright red, though it can also be pink, orange, light yellow, or (rarely) gray or black. There are 15 scale rows at midbody; the scales are keeled and the anal plate is divided. Total adult length: 20.3 to 40.6 cm (8 to 16 in).
The sexes are similar and often difficult to distinguish based on external characteristics, except when females are gravid and thus heavier-bodied than males. Males have proportionally slightly longer tails (21 percent to 25 percent of total length) than females (17 percent to 22 percent of total length). Newborn Red-bellied Snakes are 7 to 11 cm(2.8 to 4.3 in) in total length at birth. They tend tb be darker above and paler below than their parents and have a prominent light spot or collar on the neck.Back to Top
Confusing Species: Brown Snakes have paler (cream or buff colored) bellies and 17 scale rows at midbody, Kirtland's Snakes have two rows of black spots down each side of the belly, Garter and ribbon snakes have, paler bellies and undivided (single) anal plates. Northern Ring-necked Snakes have smooth, unkeeled scales.
Distribution and Status: Northern Red-bellied Snakes range from Nova Scotia south to northern Georgia and Tennessee, west to eastern oklahoma and Kansas, and north to southeastern Saskatchewan, Minnesota, and southern Ontario; they are rare or absent in large portions of the former "prairie peninsula." They occur throughout most of the Great Lakes region but are absent from the northeastern Lake Superior basin and are known from only a few scattered localities between the western end of Lake Erie and the southeastern end of Lake Michigan (northwestern Ohio, northern Indiana, and extreme southern Michigan). A southern sub-species, the Florida Red-bellied Snake (Storeria occipitomaculata obscura), extends the range into the Gulf coastal region, from north Florida to eastern Texas. A relict population in the Black Hills of South Dakota and adjacent Wyoming has been designated as a third sub-species, Storeria o. pahasapae. Red-bellied Snakes in Iowa, Minnesota, the Dakotas, and adjacent Canada may show genetic influence from this race, in which the light spots on the neck and fifth upper labial scale are faint or lacking. The Northern Red-bellied Snake is locally common in the Great Lakes region.Back to Top
Habitat and Ecology: This snake inhabits deciduous or mixed woodlands as well as adjacent fields, pastures, road embankments, marshes, and sphagnum bogs. A moist substrate is preferred, but they do turn up in drier sites. This species is sometimes found hiding under boards and other trash in urban or suburban parks, and vacant lots, along with Brown Snakes and garter snakes. Even in more natural situations much of their time is spent hiding under bark, logs, rocks, or in leaf litter. They occasionally bask in the open, particularly in spring, sometimes climbing into low shrubs, vines, and grass clumps. They may become nocturnal during hot weather. Surface activity in summer and fall is often associated with heavy rainfall. Their abundance in northern parts, of the Great Lakes basin suggests that they are quite cold-tolerant.
The yearly activity period extends from April or May into October or November, depending on local conditions. Mass migrations toward and away from hibernation sites may occur in fall and spring, respectively. These snakes often hibernate in groups of their own and other small snake species, taking refuge in anthills, abandoned animal burrows, old building foundations, and other shelters.
Northern Red-bellied Snakes feed mostly on slugs and earthworms, with snails, pill bugs, soft-bodied insect larvae, and perhaps small salamanders rounding out the diet. Like the Brown Snake, this species has jaw and tooth adaptations that assist the extraction of snails from their shells.
These little snakes are eaten by a variety of predators, including other snakes (Milk Snakes, Racers), hawks, crows, shrews, ground squirrels, raccoons, and domestic animals (dogs, cats, chickens). They rarely, if ever, bite in self-defense, and their tiny jaws and teeth would be ineffective against all but the tiniest predator. When threatened they sometimes flatten their bodies and curl their upper "lips" outward in a gesture that might be interpreted as a warning, however futile it might be. As with most area snakes, they can excrete a musky-smelling substance from the cloaca. A few "red-bellies" will, when handled, suddenly stiffen their bodies and roll onto their backs-a behavior that could be interpreted as "playing dead" (but may as well be a type of seizure brought on by stress); this does serve to expose the red belly, possibly startling the potential predator.Back to Top
Reproduction and Growth: Mating occurs most often in spring, sometimes in late summer and fall. In our region most females give birth between late July and early September. From 1 to 21 (usually about 7 or 8) young are produced per litter.
The young snakes may double their length in the first year of growth, and most become sexually mature in their second year. A captive Red-bellied Snake survived over four years, but the average and potential life span in the wild are unknow.Back to Top
Conservation: Northern Red-bellied Snakes are often most easily found by turning boards, tar paper, sheet metal, and other debris at the edges of trash dumps or abandoned buildings in or near wooded areas; they can sometimes be quite abundant in these situations. It is unclear whether the availability of such artificial cover leads to higher populations, or whether it simply makes them easier to find. Human activities that create open edges in and around woodlands probably benefit this species. However, when roads separate wintering sites and summer feeding areas, large numbers may be killed during spring and fall migrations. This harmless and inoffensive little snake should be welcomed around yards and vegetable gardens, due to its slug-eating habits.Back to Top
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: