Michigan Society of Herpetologists
NORTHERN COPPERBELLY SNAKE
Nerodia erythrogaster neglecta
Description: This large water snake is typically a uniform black, gray, or dark brown when mature, though some individuals may retain a hint of the blotched juvenile pattern. The labial scales are orangish or reddish with dark edges, and the throat and chin may be whitish to orange. The plain, unmarked belly ranges in color from pale orange to red or coppery red, though the ventral scales are often tinged by the dark dorsal color along the edges; this effect tends to be more pronounced toward the rear of the snake. There are 1 9 to 23 scale rows at midbody; the scales are keeled, and the anal plate is usually divided (single in about 10 percent of specimens). Total adult length: 67 to 141.5 cm (26.4 to 56 in).
Males are generally smaller than females and have proportionally longer tails. In males the number of subcaudal scutes ranges from 71 to 81, and the tail comprises 23 percent to 30 percent of the total length. Females have 62 to 71 subcaudals, with tails making up 19 percent to 22 percent of their total length.
At birth Copper-bellied Water Snakes range in length from 21 to 27 cm (8.3 to 10.6 in). Newborn and juvenile specimens have a pattern of dark blotches on a reddish brown or grayish brown background color; the larger blotches on the back tend to alternate with smaller ones along the sides, though these markings may fuse into crossbands near the head. Juvenile belly color is often paler than that of the adult, varying from light yellow or orange to pinkish red.Back to Top
Confusing Species:Northern Water Snakes have rows of dark spots (often half-moon shaped) on the belly, and usually retain at least a hint of a blotched pattern on the back and sides. Kirtland¡¯s Snakes and Queen Snakes also have conspicuous belly markings (rows of spots or stripes, respectively). The little Northern Red-bellied Snake rarely exceeds a length of 30cm (12 in), and has only 15 midbody scale rows.
Distribution and Status: The range of the Copper-bellied Water Snake is presently centered near the confluence of the Ohio and Wabash Rivers in western Kentucky and adjacent southeastern Illinois and southwestern Indiana. Isolated (relict) populations occur, or recently occurred, in west-central Ohio, southern and eastern Indiana, northern Kentucky, north-western Tennessee, and (within the Great Lakes basin) in south-central Michigan, northern Indiana, and northwestern Ohio. The northernmost confirmed records are in Eaton and Oakland Counties, in Michigan, where they are apparently extirpated; old unverified reports placed them as far north as Roscommon County, Michigan.
Three additional subspecies of Nerodia erythrogaster range from the Atlantic coast (Delaware and southern Virginia to Georgia) across the Deep South to Texas and northern Mexico, north to Kansas, Missouri, and the Mississippi valley as far as western Illinois and southern Iowa. Thus this is essentially a southern species that reaches its northern limit in the lower Great Lakes basin.
The Copper-bellied Water Snake is in decline throughout much of its limited range. Within the Great Lakes region, where it is presently recognized as endangered (Michigan and Ohio) or threatened (Indiana), it is very rare and restricted to a few isolated colonies. Many populations have been recently extirpated, and those that remain face continued threats from human activities. This snake¡¯s future existence in the region is precarious.Back to Top
Habitat and Ecology: Copper-bellied Water Snakes typically occur in or near shrub swamps, ponds, lakes, oxbow sloughs, fens, and slow-moving streams, usually associated with either mature or second-growth woodlands, but occasionally in more open situations. In spring these snakes often inhabit the open edges of shallow ponds and buttonbush (CephaIanthus occidentalis) swamps and frequently bask on shoreline vegetation, muskrat lodges, or woody debris. When temperatures rise and these seasonal waters begin to dry up in early summer, the snakes migrate to permanent waters (lake and stream edges), often using fairly dry wooded or grassy upland corridors. They may become largely nocturnal during hot weather. Unlike the Northern Water Snake, this species may spend considerable periods of time in relatively dry habitats away from water, apparently by choice as well as necessity. They sometimes aestivate underground or beneath logs or debris piles during hot weather or drought. An individual Copper-bellied Water Snake may occupy a home range of 20 hectares (50 acres) or more, but the vast majority of its time will likely be spent in a few small areas within this range.
Declining temperatures in fall, especially several consecutive days with low temperatures below freezing, appear to trigger migration to hibernation sites. These snakes are typically dormant from late October or November until sometime in April, usually seeking shelter in burrows or debris piles that are higher than the nearby wetlands. Occasional individuals will overwinter in crayfish burrows or other lowland sites but risk death by flooding if water levels rise during dormancy.
Most reports on the diet of Copper-bellied Water Snakes in the Great Lakes area indicate a preference for amphibians (frogs, salamanders and their larvae) and crayfish, which may reflect this snake¡¯s habit of frequenting shallow ponds and swamps where fish are scarce or absent. Fish are readily eaten when available.
Natural predators of Copper-bellied Water Snakes (particularly juveniles) include the larger fish, Snapping Turtles, herons, hawks, opossums, raccoons, foxes, otters, mink, and skunks. They are also killed by humans and domestic animals (cats, dogs, pigs). This species may be especially vulnerable to attack by hawks and terrestrial mammals when moving through upland habitats; many individuals are found with injured tails, indicating unsuccessful predatory attempts. These are alert and agile snakes-they move quickly on land, and when frightened near water they can dive to the bottom and hide amid aquatic debris and vegetation. They can remain submerged for an hour or more. If cornered or seized, a "copperbelly" may flatten its head and body and strike repeatedly, while discharging copious amounts of feces and an odorous musk from its vent.Back to Top
Reproduction and Growth: Most mating takes place between postwinter emergence in April and early June, with a peak of activity in May. At this time the adult snakes are still concentrated at basking sites along the edges of ponds and swamps. Courtship behavior has not been described in detail but appears to be similar to that of the Northern Water Snake.
Copper-bellied Water Snakes have a relatively long gestation period compared to most other viviparous snake species in the region. Females give birth to litters of 5 to 37 young (most often 8 to 20) from mid-September through mid-October. Growth and longevity data on this subspecies are lacking, but captive specimens of other subspecies have survived to known ages of 8 to nearly 15 years.Back to Top
Conservation: The Copper-bellied Water Snake is at the northern periphery of its range in the Great Lakes region, which it may have entered during the postglacial "climatic optimum," when the climate was warmer and probably wetter than at present. It possibly was fairly common and widespread in swampy forested bottomlands during presettlement times, but the cutting of these forests and conversion of wetlands to agricultural uses over the last century have left the few remaining populations of this snake isolated in pockets of ever-shrinking habitat. Human persecution and road mortality are additional threats to already diminished populations.
Any attempt to create refuges for the Copper-bellied Water Snake must take into account its tendency to make seasonal migrations between shallow wetlands and permanent waters along upland corridors. Thus, preserving a fairly large and diverse block of habitat is desirable. These snakes may tolerate certain human activities in parts of their habitat, such as fishing, hiking, selective logging, livestock grazing (other than hogs), and harvest of forage crops, as long as use of vehicles and heavy equipment is restricted to times of the year when the snakes are inactive, and the snakes themselves are left alone. Where road mortality is a problem, the seasonal closing or even rerouting of roads should be considered. Public education, along with legal protection, can minimize the persecution of these snakes by people.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: