Reptiles
Eastern Diamondback Rattlesnake
Crotalus adamanteus · also called diamondback, eastern diamondback
The eastern diamondback rattlesnake is the giant of North American vipers — the longest and by far the heaviest venomous snake on the continent, and the source of its most serious snakebite. It is also a shy ambush hunter that would much rather rattle a warning and be left alone.
Overview
Eastern diamondbacks live in the coastal plain of the southeastern United States, historically throughout the vast longleaf pine forests and associated sandhills, palmetto scrub, and barrier islands. They are ground-dwelling and largely sedentary, spending much of their time coiled and motionless in the palmetto or at the mouth of a burrow, and they depend on underground shelters — above all the deep burrows dug by the gopher tortoise — to survive fire, cold snaps, and summer heat.
Physical characteristics
The snake is heavy-bodied and boldly marked, with a row of dark, pale-edged diamonds down a background of brown, grey, or olive, and a black-and-white banded tail ending in the rattle. The broad, triangular head carries the folding fangs and, between each eye and nostril, a heat-sensing pit that lets the snake detect and aim at warm-blooded prey in complete darkness.
Hunting and the rattle
Eastern diamondbacks are ambush predators. A snake selects a spot along a mammal trail — often using scent to find a good one — coils, and waits, sometimes for days, for a rabbit or rat to pass within range. The strike is a fast stab that injects venom and releases; the snake then tracks the dying animal by scent and swallows it whole.
The rattle is a warning system, not a weapon. Made of loosely interlocking dry keratin segments, it buzzes when the tail vibrates, telling a large animal — a deer, a person — that it has come too close. A diamondback that rattles is asking to be avoided; it strikes defensively only if the threat continues.
Reproduction
Eastern diamondbacks mate in late summer and early autumn, and males wrestle in upright “combat dances” for access to females. Females are live-bearing, giving birth to around 7 to 20 fully venomous young after a gestation of six to seven months, and they reproduce only every two to three years. The newborns disperse quickly and receive no care.
Threats and conservation
Although still listed as Least Concern globally, the eastern diamondback is declining steeply and has been petitioned for protection under the US Endangered Species Act. The dominant cause is the destruction of the longleaf pine ecosystem, of which only a few percent remains. Road mortality, deliberate killing, over-collection for skins and roundups, and the decline of the gopher tortoise compound the loss. Fire suppression also degrades the open habitat both the snake and the tortoise need.
Eastern Diamondback Rattlesnake: common questions
Does a rattlesnake add one rattle segment per year?
No — that is a common myth. A new segment is added every time the snake sheds its skin, which happens two to four times a year in a young, fast-growing snake and once or twice a year in an adult. Segments also break off, so the number of rattles never reliably tells you the snake's age.
How dangerous is an eastern diamondback bite?
It is the most dangerous snakebite in North America. The venom is a potent mix that destroys tissue, disrupts blood clotting, and causes severe pain, swelling, and internal bleeding, and a large diamondback can inject a big dose through long fangs. Without antivenom the fatality rate is estimated around 10–20%; with prompt hospital treatment deaths are rare but the bite can still cause permanent damage to the limb. The snake almost always rattles a clear warning first and strikes only in defence.
Where do eastern diamondbacks live and shelter?
In the fire-maintained longleaf pine ecosystem of the Deep South — open pine woods with a grassy, palmetto understorey — plus sandhills and coastal scrub. They rely heavily on the burrows of the gopher tortoise for shelter from cold, heat, drought, and fire, along with stump holes and mammal burrows. The decline of the tortoise and its habitat is a major reason the rattlesnake is declining too.
Why are eastern diamondback numbers falling?
Habitat loss is the main cause — over 95% of the original longleaf pine forest is gone, converted to farmland, plantations, and development. On top of that, the snakes are killed on roads, deliberately killed on sight, collected for skins and for "rattlesnake roundup" events (though most roundups have now reformed or ended), and lose shelter as gopher tortoises decline. The species has disappeared from Louisiana and is rare at the edges of its range.