Eastern Diamondback Rattlesnake (Crotalus adamanteus): Facts

Appearance: how to recognize an eastern diamondback

The eastern diamondback has a brown, olive or grayish background color crossed by a row of 24–35 dark brown to black diamonds. Each diamond has a lighter center and is outlined by a single row of cream or yellow scales, which gives the snake its crisp, “lit-up” pattern. Toward the tail the diamonds fade into crossbands.

The tail carries 5–10 dark bands and ends in a rattle made of hollow, interlocking segments of keratin, the same material as human fingernails. On each side of the broad, triangular head, a dark stripe runs from the eye back to the corner of the mouth, bordered above and below by pale stripes. The belly is yellowish or cream with dark mottling at the edges.

Like all pit vipers, it has vertical, cat-like pupils and a heat-sensing pit on each side of the face between the eye and the nostril. These pits let it “see” the body heat of warm-blooded prey, even in total darkness. You can read more in how pit vipers sense heat.

Size: the heaviest rattlesnake

Most adult eastern diamondbacks are 0.9–1.8 m (3–6 ft) long and weigh about 2–5 kg (4.4–11 lb). Snakes over 2.1 m (7 ft) are rare but well documented. Unusually for snakes, males grow larger than females.

The record is less clear. A snake shot in 1946 was reported at 2.4 m (7.8 ft) and 15.4 kg (34 lb), and lengths of up to 2.5 m (8.25 ft) have been claimed, but no preserved specimens back up the biggest figures. The famous Florida herpetologist E. Ross Allen offered a cash reward for years for an 8-foot snake, and it was never claimed. For the full story of records and old claims, see how big an eastern diamondback gets.

Habitat and range

The eastern diamondback lives only in the southeastern United States. Its range follows the coastal plain from southeastern North Carolina through South Carolina and Georgia, covers the whole of Florida down to the Florida Keys, and runs west along the Gulf Coast through southern Alabama and Mississippi to southeastern Louisiana. It has not been seen in Louisiana since the 1990s and may be gone from North Carolina too.

Its classic home is the longleaf pine savanna: open, frequently burned pine woods with a grassy ground layer of wiregrass. It also uses pine and palmetto flatwoods, sandhills, coastal scrub, maritime hammocks on barrier islands, and the dry edges of marshes, cypress swamps and wet prairies.

Burrows are vital. Eastern diamondbacks often shelter in the deep burrows of gopher tortoises and in the tunnels of pocket gophers and armadillos, using them to escape summer heat, winter cold and the frequent fires that sweep through pine forests. Where gopher tortoises have vanished, diamondbacks usually decline as well.

Despite their bulk, they are strong swimmers. They are regularly seen crossing water between the Georgia mainland and the barrier islands, and in the Florida Keys. They sometimes climb into low bushes, but they spend nearly all of their time on the ground.

Diet and hunting

Eastern diamondbacks are carnivores that eat mainly mammals. In most of Florida, cottontail and marsh rabbits make up the bulk of the diet, along with rice rats, cotton rats, squirrels and mice. Birds such as northern bobwhites and towhees are also taken, and an adult can swallow a fully grown rabbit.

Most hunting is done by ambush. A diamondback picks a spot beside a rabbit trail or a fallen log, coils and waits, sometimes for days, using scent and its heat-sensing pits to detect prey. It strikes in a fraction of a second, releases the animal and then follows its scent trail until the venom has done its work.

Young snakes are already big enough at birth to swallow adult mice, so they rarely need to eat lizards or other small prey. Like many large snakes, an adult that has eaten a rabbit may not need another meal for weeks.

Behavior and the famous rattle

Eastern diamondbacks are solitary and secretive. They are mostly active by day in cool weather and around dawn, dusk and night in the heat of summer, and they spend the coldest weeks of winter sheltering in burrows or stump holes. In the warm south they may bask on any mild winter day.

Their defense depends first on camouflage. Many diamondbacks lie completely still and silent as a person walks past, relying on their pattern to blend into leaf litter and pine needles. Others start rattling from 6–9 m (20–30 ft) away. When cornered, a diamondback raises the front of its body into an S-shaped coil and can strike up to about a third of its body length.

Contrary to a popular belief, it does not have to rattle before it strikes. You can read why in do rattlesnakes always rattle before striking?. Given the chance, most diamondbacks back slowly away toward cover while facing the threat.

Reproduction, life cycle and lifespan

Eastern diamondbacks mate mainly in late summer and fall. Females can store sperm for long periods, and they give birth to live young rather than laying eggs: the eggs develop inside the mother for about four to six months.

Births take place from July to October, often in or near a gopher tortoise burrow or a hollow stump. A litter usually contains about 7–15 young, but it can range from 4 to more than 25. Newborns are 30–36 cm (12–14 in) long, fully venomous and patterned like the adults, with a single “button” at the tail tip instead of a rattle. They stay near their mother for about 10–20 days, until their first shed, and then disperse.

Each time the snake sheds its skin, a new rattle segment is added. Young snakes may shed several times a year, which is why the number of segments is not a reliable guide to age. Females reach maturity at about 2–4 years old and usually breed only every two to four years, so populations grow slowly and recover slowly from losses.

In the wild, eastern diamondbacks can live about 10–20 years, although many are killed by people or cars long before that. In captivity, the average lifespan is about 19 years, and the oldest recorded individual lived to almost 23 years.

Venom and danger to people

The eastern diamondback is often called the most dangerous venomous snake in North America. This is not because it is aggressive, but because of its size: it has, for its length, the longest fangs of any rattlesnake and a very high venom yield, averaging about 400–450 mg of dried venom per milking.

The venom is mainly hemotoxic, which means it damages blood and tissue. Bites cause severe pain and swelling and need urgent hospital treatment with antivenom. Before antivenom was widely available, a significant share of serious bites were fatal; with modern care, deaths are rare.

Most bites happen when people try to catch, kill or move a snake. The safest response is simple: watch where you step in pine woods, give any rattlesnake plenty of room and let it leave. If someone is bitten, call 911 and seek emergency medical help immediately. For the wider picture, see venomous snakes in the US.

Predators and threats

Adult diamondbacks have few natural predators, though eastern indigo snakes and kingsnakes eat rattlesnakes, and hawks, owls and some mammals take the young. The main threats come from people.

• Habitat loss. The longleaf pine ecosystem now covers only a small fraction, often estimated at under 5 percent, of its original area, after centuries of logging, farming, plantation forestry and suburban growth.
• Fire suppression. Without regular burning, open pine savanna turns into dense hardwood thicket that diamondbacks and gopher tortoises cannot use.
• Roads. Large, slow-moving snakes are often killed by traffic, and roads cut populations into small, isolated pieces.
• Deliberate killing. Many diamondbacks are killed on sight, and large snakes have long been collected for skins.
• Rattlesnake roundups. At these events, snakes are captured from the wild, displayed and often killed. Collectors have traditionally driven snakes out by pouring gasoline into tortoise burrows, which also harms the many other animals that shelter there. Some communities, including Claxton in Georgia, have replaced their roundups with wildlife festivals that do not kill snakes.

Conservation status

The IUCN Red List classifies the eastern diamondback as Least Concern because of its fairly large range, but its population trend is decreasing. Within its range the picture is worse: it is protected as endangered in North Carolina, has probably disappeared from Louisiana, and has been petitioned for listing under the US Endangered Species Act.

Conservation focuses on protecting and restoring longleaf pine habitat with prescribed fire, safeguarding gopher tortoise populations, and reducing persecution. Studies in South Carolina have tested moving snakes away from development sites, with some success.

Myths and facts

• Myth: diamondbacks always rattle before striking. Fact: many stay silent, and a snake can strike without any warning if it is stepped on or grabbed.
• Myth: you can tell its age by counting rattle segments. Fact: a segment is added at each shed, several times a year, and old segments break off. See whether rattles show a rattlesnake’s age.
• Myth: diamondbacks chase people. Fact: they are ambush hunters that usually freeze or retreat. A snake moving toward a person is almost always heading for its own shelter.

Relationship with people

The eastern diamondback has a long place in American history. A coiled rattlesnake appeared on the “Don’t Tread on Me” Gadsden flag of the American Revolution and on other early American symbols as an emblem of a creature that does not attack unless provoked.

Today the species is a flagship for the longleaf pine forest, one of the most species-rich habitats in North America. Where diamondbacks still thrive, it usually means that the gopher tortoises, fire-dependent plants and many other animals of that ecosystem are doing well too. It also shares its region with many harmless snakes; see snakes in Florida for help telling them apart.