Eastern diamond-backed rattlesnake, Eastern diamondback, Diamond rattlesnake, Diamond-back rattlesnake, Common rattlesnake, Diamond-back
The Eastern diamondback rattlesnake (Crotalus adamanteus) is a species of venomous pit viper that is found only in the southeastern United States. It has the reputation of being the most dangerous venomous snake in North America.
Eastern diamondback rattlesnakes have brownish, brownish-yellow, brownish-gray, or olive ground color, overlaid with a series of 24-35 dark brown to black diamonds with slightly lighter centers. Each of these diamond-shaped blotches is outlined with a row of cream or yellowish scales. Posteriorly, the diamond shapes become more like crossbands and are followed by 5-10 bands around the tail. The belly is yellowish or cream-colored, with diffused, dark mottling along the sides. The head has a dark postocular stripe that extends from behind the eye backward and downwards to the lip.
Eastern diamondback rattlesnakes are found in the southeastern United States from southeastern North Carolina, south along the coastal plain through peninsular Florida to the Florida Keys, and west along the Gulf Coast through southern Alabama and Mississippi to southeastern Louisiana. They inhabit upland dry pine forests, pine and palmetto flatwoods, sandhills and coastal maritime hammocks, longleaf pine/turkey oak habitats, grass-sedge marshes, swamp forests, cypress swamps, mesic hammocks, sandy mixed woodlands, xeric hammocks, and salt marshes, as well as wet prairies during dry periods.
Eastern diamondback rattlesnakes are solitary and frequently shelter by tunneling in gopher and tortoise burrows, emerging in the early morning or afternoon to bask. These rattlesnakes are terrestrial and not adept at climbing. However, they may on occasion be seen in bushes and trees, apparently in search of prey. Even large specimens have been spotted as high as 10 m (33 ft) above the ground. Eastern diamondbacks are also excellent swimmers and have often been spotted crossing stretches of water, sometimes miles from land. During cold winter months in some areas of their range, Eastern diamondbacks hibernate usually in mammal burrows, hollow logs, or among tree roots. When threatened, these snakes will raise the anterior half of the body off the ground in an S-shaped coil and can strike as far as two-thirds of their body length. Many will stand their ground and may strike repeatedly, but if given the opportunity, they will usually retreat while facing the intruder and moving backward towards shelter, after which they disappear.
The Eastern diamondback rattlesnake has the reputation of being the most dangerous venomous snake in North America. While not usually aggressive, it is large and powerful. The estimated human lethal dose is 100-150 mg. The venom contains a thrombin-like enzyme, "crotalase", capable of clotting fibrinogen, leading to the secondary activation of plasminogen from endothelial cells. Although the venom does not activate platelets, the production of fibrin strands can result in a reduced platelet count, as well as the hemolysis of red blood cells (see article on MAHA). Even with this defibrination, however, clinically significant bleeding is uncommon. Nevertheless, the venom does exhibit high hemorrhagic activity. It also contains a low-molecular-weight basic peptide that impedes neuromuscular transmission and can in theory lead to cardiac failure. This peptide is similar to crotamine from C. durrisus terrificus. In general, the venom can be described as highly necrotizing, mildly proteolytic, and containing a large phosphodiesterase fraction. It can result in severe pain, as well as profound, transient hypotension. CroFab, ANAVIP, and Wyeth's ACP are effective antivenins against bites from this species, although massive doses may be needed to manage severe cases of envenomation. Generally, ACP is very effective at countering the defibrination syndrome that is often seen but may do little for low platelet counts. Wyeth's ACP is no longer being manufactured.
Eastern diamondback rattlesnakes are carnivores. They feed on small mammals, especially rabbits and rice rats, birds, and large insects.
Eastern diamondback rattlesnakes are polygynandrous (promiscuous) which means that both males and females mate with multiple partners. They breed in the late summer and fall. Females give birth to between 7 and 21 young, usually between July and early October. The gestation period lasts around 6-7 months. Neonates are 12-14 in (30-36 cm) in length and are similar in appearance to the adults, except for having only a small button instead of a rattle on the tip of their tails. The female usually stays with her young and protects them until their first shed cycle which occurs 10-20 days after birth. After that snakelets will disperse on their own to hunt and find cover. Young females become reproductively mature at 2 and 4 years of age while males attain maturity when they are 2.5 and 3.5 years old.
The main threat to Eastern diamondback rattlesnakes is habitat loss through the development of plantations, agriculture, and expansion of urban and suburban centers. Other serious threats to this species include collecting for the skin trade and for competition in rattlesnake roundups, held annually in Alabama and Georgia.
According to IUCN, the Eastern diamondback rattlesnake is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.