Copperbelly Water Snake

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Copperbelly Water Snake

Nerodia erythrogaster neglecta

StatusThreatened (northern population)
ListedJanuary 29, 1997
DescriptionSnake with a solid dark, usually black, back with a bright orange-red underside.
HabitatBottomland hibernation sites.
FoodAmphibians and fish.
ReproductionSmall litter size; young are born in the fall.
ThreatsHabitat loss and modification.
RangeIndiana, Michigan, Ohio


The key field identification feature of the copperbelly water snake, Nerodia erythrogaster neglecta, is its coloration. The snake has a solid dark, usually black, back with a bright orange-red underside that is visible from a side view. The head and eyes of the copperbelly water snake are proportionally larger than similar species. The copperbelly water snake is most often confused with the yellowbelly water snake, an adjacent subspecies to the south and west in Illinois and Kentucky. The most obvious single distinguishing characteristic is the belly color. The copperbelly water snake has a bright orange-red underside, whereas the yellowbelly water snake has a pale yellow belly. In addition, it has blotches of dark pigment extending onto the ventral scales that meet or nearly meet at the belly, whereas the yellowbelly water snake has dark pigment encroaching onto only the edge of the ventral scales.


Copperbelly water snakes migrate seasonally throughout their habitat, which consists of bottom-land forests and shrub swamps. Although the species is a "water" snake, much of its time is spent away from water in the terrestrial, forested part of its habitat. Copperbelly water snakes emerge from their hibernation sites in early spring and migrate through wooded or vegetated corridors to wetland areas. They can often be seen basking, breeding, and foraging near shallow wetland edges in woodlands. When the woodland swamps begin to dry in late spring or in early June, the snakes again disperse and move through wooded or vegetated corridors to their summer habitat areas. Summer activities usually center around forest and forest edges. For this reason, upland habitat is essential for the snake's summer foraging activities. By late fall, copperbelly water snakes seek out hibernation sites.

This species is known to form small groups in the spring and fall. Groups of snakes have been observed swimming, feeding, courting, and resting together. Courtship and mating occurs in April, May, and June. Copperbelly water snakes have a longer gestation period than other water snakes sharing their range, and their average litter size is also smaller. Young snakes are born in the fall near, or in, the hibernation and may not become active until the following spring. This species feeds on amphibians and fish.


It is believed that copperbelly water snakes use hibernation sites that are at elevations higher than the floodstage line and ponding areas. Copperbelly water snakes utilize bottomland hibernation sites. Bottomland hibernation sites have been identified as felled tree-root networks, crayfish burrows, dense brush piles, fieldstone piles, and perhaps beaver and muskrat lodges. These studies indicate that upland hibernation sites are essential to the long-term survival of viable populations of the snake. A mid-winter flood, coupled with freezing temperatures, could be lethal to snakes and could decimate the local copperbelly water snake population if floodplain and riverbank areas are the only hibernation sites available.


The distribution of the copperbelly water snake is clearly divided into a southern segment in southeastern Illinois, western Kentucky, and southern Indiana; and an isolated northern segment in northern Indiana, southern Michigan, and northwestern Ohio.

Currently, within the southern population segment there are five local clusters known in Illinois, 18 in Kentucky, and 13 in southern Indiana. The northern population segment consists of eight local clusters that are known to have had the species present in the 1990s; copperbelly water snakes were found at five of these northern sites during 1996 surveys. Local clusters consist of snakes within connected, or nearly connected, habitat units and which are able to interbreed because of this proximity.

It is believed, based on drainage patterns and post-1949 records of copperbelly water snakes, that its former range was nearly continuous over the three southern states. Only remnants of that original distribution are still evident, however; coal mining, drainage and damming of wetlands, channelization, damming and diversion of streams and rivers, and residential and commercial development of its habitat have disrupted and fragmented the distribution of the copperbelly water snake. Many once-connected local clusters are now isolated.

In Illinois, the copperbelly water snake distribution is believed to once have been continuous through southern Illinois; however, due to continued habitat loss and fragmentation, only five small, isolated local clusters remain.

Kentucky, historically and presently, is considered to have the largest number of copperbelly water snakes rangewide. It is believed the species was once abundant and continuous throughout the western Kentucky coal field. The once-continuous range of the copperbelly water snake is now restricted to 18 isolated local clusters.

Similarly, in southern Indiana, the distribution of the species has been fragmented into 13 discrete populations.

The northern population segment has experienced extensive habitat loss; and the impacts from habitat fragmentation and degradation on this smaller population are very pronounced. Consequently, the northern population segment has been relegated to a few small, scattered and isolated local clusters in southern Michigan, northeastern Indiana, and northwestern Ohio. Under current conditions and trends, extirpation of the northern population is expected to occur within the next few decades.


Habitat loss and fragmentation were the primary causes of the decline of the copperbelly water snake and continue to be the major factors threatening the continued existence of the species. From 1790 to the mid-1980s, much of the copperbelly water snake's wetland habitat was modified or destroyed. By 1990, Indiana has lost 87% of its original wetlands, Illinois 85%, Michigan 50%, Ohio 90%, and Kentucky 81%. The principal cause of these losses was land conversion to agricultural use. This was especially true from 1950 through the 1970s, when agriculture was cited as the cause for 87% of the wet-land loss nationwide. However, since that time, other land uses and modifications such as dredging, coal mining, stream channelization, road construction, and commercial and residential development have played a more significant role in the loss of wetland habitat.

The loss of snake habitat is especially evident in areas occupied by the northern population segment of the snake, where the species has been relegated to only a few small, isolated habitat areas. The northern population segment has, since 1986, occupied only eight very limited sites in four southern Michigan counties, one northwestern Ohio county, and one northeastern Indiana county. Six of these local clusters, including the Indiana and Ohio local clusters, are encompassed within an area of about 100 sq mi (260 sq km). The other two local clusters are 35-60 mi (55-95 km) to the northwest.

Two of the eight sites have a portion of their area protected by state ownership, and one is partially owned by a private conservation organization. The remaining sites are all private property with uncertain fates. A key characteristic of these sites is separation by unsuitable habitat from each other and from important habitat components. The unsuitable habitat is primarily agricultural land, rural residential sites, and roads.

Landscape fragmentation and isolation of local clusters from each other increases the likelihood of extinction by causing each local cluster to function as an independent, but much smaller population. Very small populations are far more susceptible to local extirpation from factors such as drought and from genetic irregularities caused by inbreeding.

Other factors that may be adversely affecting northern population habitat include increased residential development, sedimentation, and contamination caused by fertilizer runoff. A large residential complex has been developed around a deep water lake that is utilized by the snake during droughts. New residences have been built near the Cass/St. Joseph counties local cluster. Residences add to roadway traffic, increase habitat fragmentation, and increase the likelihood of direct harm to snakes by people, pets, and vehicles. Sedimentation, usually resulting from agricultural activities, but also caused by construction, may change hydrological characteristics and plant succession, as well as reduce the numbers of amphibian and fish used by the snake as food.

The presence of copperbellies at two of the eight northern local clusters has not been confirmed since 1987, and since 1989 at a third site. Two of these three sites were surveyed in 1996, one of them for 46 hours, and no copperbellies were found. The third site has not been surveyed since 1987. Suitable habitat at these three sites still seems to be available. While it may be reasonable to conclude that snake numbers at the two recently surveyed sites have declined, surveys have not been frequent enough to conclude with certainty that these two local clusters no longer support copperbellies. Northern population survey data since 1986 are not complete for all local clusters, and do not support any conclusion as to an overall trend of increase or decrease. However, total numbers of snakes seen have remained very low since 1986. The low numbers and possible disappearance of snakes from various sites in the last ten years indicates that progress toward extirpation which became apparent in the 1950s and 1960s probably is continuing, and underscores the perilous state of the northern population segment. The northern population probably will be extirpated within the next few decades without immediate additional protection.

Specific habitat-related threats that have cumulatively led to the extirpation of northern population segment copperbelly water snake local clusters include woodlot, brush, and other land clearing; habitat constriction and fragmentation from surrounding development; road construction; and coal mining.

Although coal mining has been a major recent factor in the decline of the species in the southern portion of its range, U.S. Fish and Wildlife Service (FWS) believes mining practices can be compatible with the existence of the snake. Coal mining can be compatible with the copperbelly water snake if the extent, the timing of the mining, and the reclamation design are modified to incorporate snake conservation measures. The Conservation Agreements for the southern population segment make such changes to coal mining and reclamation practices, thus greatly reducing mining threats to the species, and providing compatibility between mining and snake conservation. Because habitat loss and degradation from surface coal mining constituted the main threats facing the southern population, the FWS believes that the reduction of the coal mining impacts by the Conservation Agreements precludes the need to list the southern population segment.

While the northern population segment is not impacted by coal mining, it is significantly affected by all of the other threats of destruction, modification, or curtailment of its habitat listed above. Scientific overutilization, without careful regulation, can pose a threat. During the first 30 years after its discovery and formal publication of its description, many copperbelly water snakes were collected as specimens for museums. Although museums have abandoned this practice, amateur collectors continue to take wild snakes. The species is believed to be collected fairly regularly because of its rarity, large size, unique coloration, and value in the pet trade. For example, an international commercial dealer reportedly offered US$260 to an amateur collector for a breeding pair of copperbelly water snakes.

The snakes are vulnerable to predation during migration, especially when their migration routes are interrupted by cleared areas such as roads, mowed areas, and farmlands. Dispersing through such areas increases the likelihood of the snakes being preyed upon by natural predators such as skunks, raccoons, and raptors. Due to habitat fragmentation, the ability to use suitable cover to migrate safely throughout its home range is a limiting factor in the life cycle of the copperbelly water snake. In addition to predation, vehicle-caused mortality and injury also has increased as suitable habitat becomes more fragmented by transportation corridors. Such habitat fragmentation is especially significant to the northern population segment where seasonal movements among its smaller habitat patches force snakes to cross roadways or other open habitat.

Weather extremes such as drought, flooding, and unusually mild, as well as severe, winters may influence the population of the copperbelly water snake. These factors affect the snake's ability to estivate for prolonged periods, as well as impeding access to, and use of, essential upland hibernation and foraging sites and wetland breeding areas. While these factors are not as likely to affect larger and healthier populations, small, isolated copper-belly water snake local clusters, like those that make up the northern population segment, are especially vulnerable to these naturally occurring events.

The widely held general dislike for snakes by humans further threatens copperbelly water snakes. Two incidents were reported in which the species was intentionally killed, with a gravid (pregnant) female being one of the victims. Such intentional killing likely has been more common in the southern population segment, due to geographic proximity to poisonous wetland-inhabiting snakes.

Conservation and Recovery

The copperbelly water snake receives varying degrees of protection through state listings as an endangered, threatened, or nongame species throughout its range. Michigan, Indiana, and Ohio confer full legal protection to the copperbelly water snake; it is illegal to collect, kill, or injure the snake in these three states. Illinois and Kentucky offer no legal protection to the snake at this time.

Whereas three states have laws and regulations which protect the species from take, the lack of uniform protection throughout the United States hampers enforcement and imperils the species by creating loopholes for illegal take and trade. More importantly, legal provisions for protection and management of copperbelly water snake habitat at the state level are non-existent. Because destruction and alteration of habitat are the major reasons for the species' decline, the inability to protect non-federally listed species' habitat will exacerbate the continued decline of the copperbelly water snake without additional federal protection.

Since the 1993 proposal for the threatened listing of the copperbelly water snake there have been several parallel efforts to develop formal methods to reduce threats to the species and its habitat. These efforts have coalesced into two Conservation Agreements. One Agreement deals specifically with the effects of coal mining in Indiana. The second Agreement covers the impacts of coal mining in Kentucky and Illinois and also institutes other conservation measures in all three states.

The Conservation Agreements will promote the conservation of the copperbelly water snake and its habitat during surface coal mining in Indiana by delineating approximately 10,400 acres (4,210 hectares) of high quality copperbelly water snake habitat as core habitat areas that will not be affected by surface coal mining. Furthermore, the Agreements require the maintenance of habitat corridors connecting all other copperbelly water snake habitats, restrict the mining of large habitat fragments that are outside of the core areas to practices that will ensure the survival of existing copperbelly water snake local clusters, and ensure that all snake habitat that is mined will be reclaimed in such a way as to increase both the quantity and quality of snake habitat.

In Kentucky the Conservation Agreements provide that a maximum of four percent of the approximately 112,400 acres (45,500 hectares) of known copperbelly water snake habitat can be disturbed by surface coal mining activities. All copperbelly water snake habitat has been divided into management units of which no one unit may have more than 10% of its area disturbed by mining activities, and all copperbelly water snake habitat that is mined will be reclaimed in such a way as to increase both the quantity and quality of snake habitat.

Similarly, in Illinois, the Agreements require that all copperbelly water snake habitat that is mined will be reclaimed in such a way as to increase both the quantity and quality of snake habitat.

The Conservation Agreements also ensure that in all three states within the southern population segment the state natural resource departments will emphasize land acquisition, management, and law enforcement to manage and conserve the copper-belly water snake as if it were a federally listed species. In Illinois and Kentucky, where the snake is not listed as threatened or endangered by the states, there will be special regulations written to provide the species with protection from take. In addition, the Office of Surface Mining Reclamation and Enforcement will prioritize their Clean Stream initiative program to aid protection and enhancement of copperbelly water snake habitats. The Farm Bureau's role will be to publicize the conservation needs of the snake to its members.

These provisions of the Conservation Agreements significantly reduce the threats from surface coal mining at all known copperbelly water snake local clusters in the southern population segment. Because habitat destruction and degradation resulting from surface coal mining was the predominant recent threat to the southern population segment, this population is no longer threatened at this time.


U. S. Fish and Wildlife Service
Bloomington Ecological Services Field Office
620 South Walker St.
Bloomington, Indiana 47403-2102
Telephone: (812) 334-4261
Fax: (812) 334-4273

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1 Federal Drive
BHW Federal Building
Fort Snelling, Minnesota 55111
Telephone: (612) 713-5360


U.S. Fish and Wildlife Service. January 29, 1997. "Determination of Threatened Status for the Northern Population of the Copperbelly Water Snake." Federal Register 62(19): 4183-4192.