Justification
Listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.
Geographic Range Information
This species is endemic to the southeast of the United States. Its range encompasses the Coastal Plain of the southeastern United States from North Carolina to south Florida, and west to Mississippi and the Florida parishes of Louisiana, at elevations extending from near sea level to around 500 m (Mount 1975, Dundee and Rossman 1989, Palmer and Braswell 1995, Ernst and Ernst 2003, Campbell and Lamar 2004). The major stronghold today is the northern Florida peninsula, eastern and southern Florida panhandle, and southwestern Georgia (Timmerman and Martin 2003). North Carolina: restricted to the Lower Coastal Plain south of the Neuse River; formerly occurred in the middle Coastal Plain but apparently never in the North Carolina Fall Line sandhills; not known on North Carolina barrier islands. South Carolina: patchily distributed in the lower and middle Coastal Plain; common in the coastal marsh-sea island area, occurring on Edisto and three smaller barrier islands. Georgia: restricted to the Coastal Plain, occurring on the Fall Line sandhills below Columbus (Fort Benning) and thriving on Georgia's sea islands. Florida: throughout the state, including many of the Florida Keys and most of Florida's east and west coast barrier islands. Alabama: does not range to the Fall Line but occurs in the lower Coastal Plain where longleaf pine and wiregrass dominated the uplands originally; has been recorded from Dauphin Island. Mississippi: occurs today principally in the counties of the southeastern portion of the state, east and northeast of the eastern tip of Louisiana; historically may have ranged to the limits of the longleaf pine forest, but today the range has contracted and is confined mainly to the longleaf pine hills and pine flats regions; there are no records from Mississippi barrier islands. Louisiana: nearly extirpated; was confined to the easternmost three of the seven Florida parishes, and never was reported from Louisiana barrier islands (Means unpublished manuscript).
Population Information
This species is represented by a large number of occurrences (subpopulations). On a range-wide scale, Campbell and Lamar (2004) mapped roughly 175 collection sites; however, relatively few of these represent extant populations with good viability. The adult population size is unknown but presumably exceeds 100,000 (several thousand are killed annually for the skin trade). This snake is rare in North Carolina (Palmer and Braswell 1995) and Louisiana (Dundee and Rossman 1989). However, it is still locally common in suitable habitat in some areas of Georgia, South Carolina, and Florida (Ernst and Ernst 2003). Its area of occupancy, number of subpopulations, and population size clearly have declined significantly compared to the historical situation. This species probably ranged throughout the original extent of the longleaf pine forest in the Coastal Plain, but the longleaf pine forest now occupies only a small percentage of its former extent (Ware et al. 1993). longleaf pine upland habitat has shrunk from 60.6% to less than 1.4% of the landscape since presettlement times (Ware et al. 1993), so that the principal natural habitat of the species has diminished greatly. Many animals endemic in the longleaf pine forest such as the Gopher Tortoise and this rattlesnake are suffering range contractions because of the loss of the longleaf pine forest upland habitat in which they evolved and to which they are best adapted. Range contractions are known from Louisiana, Mississippi, and South and North Carolina. This snake is now very rare or virtually extirpated at the northern and western extremes of the range in North Carolina (Palmer and Braswell 1995) and Louisiana (Dundee and Rossman 1989). Its area of occupancy, number of subpopulations, and population size are probably declining throughout its range. The habitat continues to be drastically reduced at the northern extent of the range in North Carolina (Palmer and Braswell 1995). Substantial habitat loss is continuing in Florida (Tennant 1997). The rate of decline is unknown, but it may exceed 10% over three generations (probably at least 15 to 20 years). Eastern diamondbacks have been able to occupy many of the ruderal habitats that have sprung up in place of the native longleaf forest habitats, but these are also declining in percentage of the landscape (Ware et al. 1993, Means 1995).
Habitat and Ecology Information
Habitats include pine and wiregrass flatwoods, pine-palmetto flatwoods, longleaf pine-turkey oak hills, rosemary scrub, mesophytic and coastal maritime hammocks, xeric hammocks, barrier islands and coastal scrub habitats, vicinity of wet savannas, wet prairies (during dry periods), mixed pine-hardwood successional woodland, and abandoned farms and fields (especially near pine-dominated habitats), particularly areas with abundant cover (Mount 1975, Dundee and Rossman 1989, Palmer and Braswell 1995, Tennant 1997, Ernst and Ernst 2003, Campbell and Lamar 2004). This snake usually does not occupy marshes or swamps but may pass through these habitats or occupy their edges. Large tracts of habitat are most suitable. Eastern diamondbacks are basically terrestrial and rarely climb into vegetation. Shelters include stump holes, burrows of other animals, brush piles, or similar sites. Stumpholes in shortleaf-loblolly pine oldfield successional forest are utilized more frequently than burrows of the gopher tortoise (Means 1995). Eastern diamondbacks can tolerate temporary inundation of their overwintering burrows (Means 1982, 1995). According to Ernst (1992), most young are born in retreats such as gopher tortoise burrows or hollow logs.
Threats Information
The original range has been reduced and fragmented by agriculture, forestry practices, urbanization, and plant succession resulting from fire suppression (Martin and Means 2000). Current threats to local populations include conversion of native habitat to planted slash or loblolly pine silvicultural plantations, agricultural fields, and urban and suburban uses. More than anything else, human alteration of native longleaf pine upland ecosystems (including fire suppression) is shrinking and fragmenting the suitable habitat base for this species. Another direct threat is the collecting of rattlesnakes for the skin trade and for competition for prizes in rattlesnake roundups held annually in Alabama (1) and Georgia (3). While probably not a serious threat in itself, when coupled with habitat loss, this sort of collecting is additive. It utilizes the practice of gassing the burrows of the Gopher Tortoise in winter (illegal in Florida and Georgia), sometimes killing rattlesnakes outright, and usually impacting the other fauna inhabiting burrows (Speake and Mount 1973). Rattlesnake roundups, themselves, account for only about 2,000 snakes per year. The skin trade is more insidious. Skin dealers have a huge network of pick-up stations where they advertise for people to bring in killed snakes to be frozen until the dealers can make the rounds and pick up the carcasses. Rangewide, this sort of activity probably accounts for at least ten times (20,000) the number of rattlesnake deaths caused by roundups (Means 1995). Berish (1998) provided further information on the harvest in Florida.
Use and Trade Information
Conservation Actions Information
Several occurrences are in protected areas. As of early 1995 there were no state or federal statutes specifically prohibiting the taking of the Eastern Diamondback Rattlesnake. Some states (Georgia, Florida) prohibit the gassing of Gopher Tortoise burrows, but do not place limits on the taking of this species. Improved state regulations pertaining to this species are needed. This snake should at least be given the status of a game animal, and the taking of specimens should be regulated by bag limits. Licenses should be required of people taking rattlesnakes. Out-of-state licenses should be much more expensive than in-state licenses. The sale of Eastern Diamondback Rattlesnakes should be regulated in the same manner as any game animal; interstate commerce should be prohibited.