Types: None designated.

Type-locality: Not specifically stated in original description. Proposed by Schmidt, Check List N. Am. Amph. Rept., 6th ed., 280pp.[230] (McDiarmid et al., 1999).

Eastern diamondback rattlesnake

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The 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 meters (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to the easternmost three of the seven Florida parishes, and never was reported from Louisiana barrier islands (Means, unpublished manuscript).

The Eastern Diamondback lives in the coastal lowlands, ranging from southeast North Carolina to eastern Louisiana, and throughout Florida, including the Florida Keys. (Conant and Collins 1998)

Biogeographic Regions: nearctic (Native )

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Southeastern USA: along the Gulf Coast from southeastern Louisiana and southern Mississippi eastward through peninsular Florida, including the Florida Keys, northward along the coastal plain to southeastern North Carolina (McDiarmid, et al. 1999)

The Eastern diamondback is one of the largest North American snakes, with a record length of 8 feet. However, they are usually 33 to 72 inches in length. The snake has a large head and a bulky body. It has a row of large dark diamonds with brown centers and cream borders down its back. The ground color of the body ranges from olive, to brown, to almost black. The tail is usually a different shade, brownish or gray, and banded with dark rings. At the end of the tail is a well-developed rattle. The head has a light bordered dark stripe running diagonally through the eye. The pupil is vertical (catlike). There is a large pit between the nostril and eye. The young are similar to the adults in color pattern. The tip of the tail of a newborn diamondback ends in a button, which is the first segment of the future rattle. Male and female rattlesnakes look alike. (Conant and Collins 1998, Ashton and Ashton 1985)

Length: 244 cm

This species differs from other rattlesnakes by the following characteristics: crisp dorsal thin yellow diamonds enclosing black pigment centered with brown; densely black face with two thin oblique yellow lines on either side of the black eye (the iris and sclera are not set off from the pupil); olive-brown tail never with bold black and white "coon tail" bands.

• Terrestrial

The Eastern Diamondback resides in the palmetto flatwoods and dry pinelands of the South. It generally avoids marshes and swamps, but on occasion will live near the borders of wetlands. Occasionally it may venture into salt water, swimming to the outlying Keys off the Florida coast. (Conant and Collins 1998, Ashton and Ashton 1985)

Terrestrial Biomes: chaparral ; forest

Comments: 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). 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, unpublished manuscript). Eastern diamondbacks can tolerate temporary inundation of their overwintering burrows (Means 1982, unpublished manuscript). According to Ernst (1992), most young are born in retreats such as gopher tortoise burrows or hollow logs.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Apparently does not defend a territory. In longleaf pine sandhills habitat, Timmerman (1989) found that females occupied smaller areas (mean=46.5 ha, N=2) than did males (mean=84.3 ha, N=4). Means (unpublished manuscript) measured home range in clayhills habitat in shortleaf/loblobby pine oldfield successional forest that was annually control burned and found males to occupy home ranges of approximately 240 ha (600 acres) and females about 120 ha (300 acres).

In November, makes short movements to one or more holes in the ground used for overwintering (Means, unpublished manuscript); the same holes are utilized in subsequent years. After spring emergence, moves various distances (100-500 m) to find sites with food. Individuals may move as much as a mile (1.6 km) between hunting locations in just one day, but most movements are much shorter (Timmerman and Martin 2003).

The Eastern diamondback feeds primarily on small mammals, from mice to rabbits. It will also eat birds. Young diamondbacks feed primarily on rats and mice, while adults prefer larger prey like rabbits and squirrels. The snakes lie waiting for prey beside logs or near the roots of fallen trees. Diamondbacks locate their prey by odor, as well as by sensing the infrared waves (heat) given off by their warm-blooded prey. Once found, the prey is bitten. The prey is released after the strike, and is then allowed to crawl away and die. The snake will pursue the prey, eating it once it is dead. (Ashton and Ashton 1985, King 1996)

Comments: Prey is principally rodents and lagomorphs, including the eastern cottontail (Sylvilagus floridanus), marsh rabbit (Sylvilagus palustris), cotton rat (Sigmodon hispidus), cotton mouse (PEROMYSCUS FLORIDANUS), grey squirrel (Sciurus carolinensis), fox squirrel (Sciurus niger), and other rodents. Very few birds (bobwhite quail, rufous-sided towhee, king rail, brown thrasher) and no ectothermic vertebrates have been recorded as prey (Means, unpublished manuscript). Employs sit-and-wait ambush behavior; trails envenomated prey very accurately after a refractory period of 2.5 to 39 minutes (Brock 1980); ingests the prey whole, usually head first.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: 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.

100,000 - 1,000,000 individuals

Comments: 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).

Reported density ranges from about 18 individuals/ha in muhlenbergia grass on a barrier spit to one individual per 6 ha in shortleaf/loblolly pine oldfield successional habitat on clayhills (Means, unpublished manuscript). The acreage required to maintain a minimum viable population is not yet known.

The principal predators and enemies are other snakes, including the indigo snake (Drymarchon corais COUPERI), which feeds upon diamondbacks, and the eastern kingsnake (Lampropeltis getulus), which takes young rattlesnakes occasionally. The red-tailed hawk is a known predator and several other birds of prey are suspected of feeding on medium- and small-sized rattlesnakes. Feral hogs have been reported to kill and feed on small rattlesnakes and white-tailed deer have been reported to stamp rattlesnakes to death (Timmerman 1989; Means, unpublished manuscript). Fire is a known source of mortality, albeit probably not very important (Means, unpublished manuscript). No doubt humans are presently the most serious source of direct mortality (roadkilling, clubbing, shooting, and collecting for sale of skins or for rattlesnake roundup competitions) (Means, unpublished manuscript).

Comments: Most activity occurs from April to October, but these snake commonly make visits to the ground surface on warm days in the winter and sometimes may feed then. Active occurs mainly in early morning, evening, and at night.

Average lifespan

Status: captivity: 22.8 years.

Eastern Diamondbacks mate in the late summer and fall. The size of the brood ranges from 6 to 21 young. The gestation period is six to seven months. Young are born live, in retreats such as gopher tortoise burrows or hollow logs. At the time of birth, the baby snakes are 15 inches long. The snakes can live 20 years or more. (Georgia Wildlife Federation 1999)

Mating takes place in August and September. Females store sperm until the following April when ovulation and fertilization take place. Gestation requires about 120 days. Vitellogenesis begins in the ovaries of females in the fall preceeding gravidity and birth (Means, unpublished manuscript). Females give live birth in August and September to an average of about 14 young. Females may remain in the vicinity of the newborn for several days. Males may reach sexual maturity by the time of their second birthday; females at year three (Means, unpublished manuscript). Males and females both probably participate in courtship and mating every August and September after reaching sexual maturity, but females usually reproduce every two or possibly three years after giving birth to their first clutch (Means, unpublished manuscript). In captivity, individuals have lived for more than 22 years (Bowler 1977).

Though not endangered, the Eastern Diamondback is clearly in trouble. The snake is rapidly disappearing from many areas in which it formerly occupied. Suburban housing and agricultural development destroys vast areas of habitat for the rattlesnake. Most snakes are killed on sight when found by humans. 'Rattlesnake roundups' held annually in several states of the U.S. further decrease their numbers. Crotalus adamanteus is regulated in North Carolina, a permit is required to

collect it, and in Florida a permit is needed to possess all vcenomous snakes. (King 1996, Georgia Wildlife Federation 1999, Levell 1997)

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Global Short Term Trend: Decline of 10-30%

Comments: Area of occupancy, number of subpopulations, and population size probably are declining throughout the 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 percent over three generations (probably at least 15-20 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, unpublished manuscript).

Global Long Term Trend: Decline of 30-70%

Comments: Area of occupancy, number of subpopulations, and population size clearly have decllined 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).

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: 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, unpublished manuscript). Berish (1998) provided further information on the harvest in Florida.

Restoration Potential: The eastern diamondback rattlesnake fares well in adequate habitat. Viable populations are maintained on islands of a few tens to hundreds of acres. Individuals have been observed swimming in the ocean and in estuaries along the coast. Barrier islands and the Florida Keys are populated with the eastern diamondback rattlesnake, so dispersal and founding of populations has been accomplished under natural circumstances. Restoring Crotalus adamanteus to any suitable site should not be a problem.

Preserve Selection and Design Considerations: The most important consideration in the management of the eastern diamondback rattlesnake is that the area managed should be restored and maintained as close to natural to its presettlement condition. For this species this is a mosaic of wetland and upland habitats associated with longleaf pine forest that is control burned on a 1-5 year frequency in the season May-July. Such a landscape should have its native complement of other animals present in viable populations (food species and the gopher tortoise). Other than control burning, no special management actions are required as presently known.

Management Requirements: The presettlement landscape is the best landscape in which to maintain the eastern diamondback rattlesnake. Under natural conditions the uplands of the Coastal Plain landscape burned over from lightning ignitions as frequently as 1-5 years. Since lightning strikes are not sufficient to ignite areas of only several square kilometers, and since weeks-long fires that burned over several counties in area are not presently possible, controlled burning that mimics the natural fire frequency and season of burning is the principal management requirement necessary to maintain the landscape in the condition most suitable for this species. In the absence of fire, hardwoods eventually invade the open longleaf pine upland habitats and cause them to be grossly altered by plant succession. A landscape dominated by southern temperate hardwood forest (Platt and Schwartz 199X ) or Southern Mixed Hardwood Forest (Ware et al. 1993) is not suitable for the eastern diamondback rattlesnake.

See also Timmerman and Martin (2003).

Management Research Needs: More research on minimum viable population and size of the area required to maintain a minimum viable population is needed. Research is needed to determine what role food supply plays in the reproductive health of females, and whether females could reproduce annually or shorten their ages to maturity by access to unlimited food supply. Very little is known about the first two years of life, when individuals are less than 1.0 meters long. This critical stage in the life history has not been examined. It is believed that rattlesnakes are more vulnerable to predation at young sizes (=ages) and that they are more fossorial during these years (Means, unpublished manuscript).

Biological Research Needs: It is necessary that we learn more about the effects of collecting for the skin trade and gassing of gopher tortoise burrows regionally because of possible unregulated impacts on the eastern diamondback.

Needs: 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.

none

This snake is extremely beneficial to man. It preys on rats, mice, rabbits, and other small mammals, many of which are pests to humans. (Ashton and Ashton 1985)

Comments: Venomous, and highly dangerous to humans; defensive if disturbed, but unaggressive if left alone; see Ernst (1992) for information and references pertaining to envenomation of humans.

Stewardship Overview: Basic life history and ecology information is in the process of being worked up for publication by D. B. Means based on an intensive study of the species over an 8-year period, so more explicit information eventually will be available. This species has been declining over its geographic range in several ways. First, the northern perimeter of the range has been shrinking southward. Second, the western and northeastern ends of the distribution are shrinking toward the middle of the range. Third, throughout the range, the habitat and thus the opportunity for a globally panmictic population has been severely fragmented by humans. The best way to arrest this trend is to manage occupied habitat in ways that promote the preservation and/or maintenance of the full complement of native ecosystems originally thought to have occurred naturally on each site. Usually this is longleaf pine forest on the uplands and wetland habitats naturally adjacent to them, all of which were kept in good condition for the eastern diamondback when fires burned through longleaf pine on a natural May-July season on a 1- 5 year interval, and were allowed to burn into adjacent habitats as far as conditions in those habitats would permit. Killing of eastern diamondbacks should not be permitted nor harvest for commercial purposes from managed lands. Until biologists know differently through further research, it appears that the eastern diamondback rattlesnake will hold its own on large tracts (>2,000 acres) with no specific managment targeted strictly for the species. In other words, if the gradient of natural habitats is intact the species should fare well.

Species Impact: The most significant impacts of the eastern diamondback rattlesnake on other animals is as a predator on rodents and rabbits. A very small number of eastern diamondback snakebites impact human beings every year (less than about 10), and many of these are delivered to people deliberately handling the animals (snake fanciers, roundup yahoos, researchers).