The Red-Bellied Snake (Storeria occipitomaculata) occupies an extensive range across eastern North America, from the Maritime Provinces of Canada through the Great Lakes region and southward along the Appalachian Mountains into the upper Gulf Coast states. Understanding the geographic extent and ecological character of this range is the essential first step in planning a field trip to observe the species, as the probability of encounter and the specific habitats to target vary significantly across the distribution.
In the northeastern United States and southeastern Canada, the Red-Bellied Snake is associated primarily with deciduous and mixed forests at low to moderate elevations. The species is widespread in the hardwood forests of New England, New York, and Pennsylvania, where it inhabits the moist leaf litter and decomposing woody debris that characterize mature forest floors. Populations extend northward into the forested regions of Ontario, Quebec, New Brunswick, and Nova Scotia, where the species approaches the northern limits of its climatic tolerance and tends to be restricted to relatively sheltered, south-facing sites that provide adequate thermal conditions for activity and reproduction.
The Great Lakes states, including Michigan, Wisconsin, and Minnesota, support robust Red-Bellied Snake populations in the mixed forests and woodland edges that cover much of the region. These midwestern populations benefit from the extensive tracts of contiguous forest habitat that remain in the region, and Red-Bellied Snakes can be found at relatively high densities in suitable habitat throughout the northern portions of these states. The species' distribution becomes patchier toward the western and southern margins of the Great Lakes region, where forest habitat gives way to the prairies and agricultural landscapes of the central United States.
The Appalachian Mountains provide a corridor of suitable habitat extending the Red-Bellied Snake's range deep into the southeastern United States, where the species occurs at moderate to high elevations in the moist, forested habitats of the Blue Ridge, the Great Smokies, and adjacent mountain systems. These southern montane populations are of particular interest to field observers because they tend to exhibit the full range of the species' dorsal color variation, from dark gray and brown morphs to the striking bright orange and black forms that are among the most visually impressive expressions of the species' phenotypic diversity. The disjunct population in the Black Hills of South Dakota represents the westernmost extension of the species' range and provides a unique field observation opportunity for travelers in the northern Great Plains.