Reptiles
Western Diamondback Rattlesnake
Crotalus atrox · also called western diamondback, Texas diamond-back, coontail rattler
The western diamondback is the snake most Americans picture when they hear a rattle: a heavy, grey-brown pit viper coiled in the dust, tail buzzing, ready to hold its position. It causes more serious snakebites than any other species in the United States — a fact of geography and temperament more than of venom.
Overview
Crotalus atrox ranges across the southwestern United States and northern Mexico, in desert, thornscrub, and dry grassland. It is usually 1–1.2 m long, patterned with dark diamonds down the back and a tail ringed in black and white — the “coontail.” Heat-sensing facial pits let it aim at warm prey in the dark.
Why it leads the bite statistics
Its venom is not the strongest of the US rattlesnakes. But the diamondback is large, abundant, lives near people, and stands its ground, rattling and facing a threat rather than fleeing. More encounters mean more bites. With prompt antivenom treatment, bites are rarely fatal.
The rattle
The rattle is interlocking keratin segments, one added per skin shed — not per year — and often broken off in rocky ground. Tail muscles buzz it around 50 times a second.
Life cycle
Females bear 10–20 live young in late summer, each with a “button” and working venom. In cooler areas, snakes overwinter communally in rock dens.
Status
The western diamondback is Least Concern and stable, though roads, habitat loss, and “rattlesnake roundups” apply local pressure.
Western Diamondback Rattlesnake: common questions
How dangerous is a western diamondback bite?
It is a serious medical emergency that needs hospital treatment, but it is very survivable with prompt care. The venom is a mostly tissue-destroying and blood-affecting mix that causes severe pain, rapid swelling, bruising, blistering, and sometimes lasting local damage, along with effects on blood clotting and, in bad cases, on blood pressure. Modern antivenoms neutralise it well. With treatment, deaths are rare; without it, or after a large dose or a bite to a child, the risk is real. The reason this species leads United States bite statistics is not exceptional venom potency but the number of encounters and the snake's readiness to defend itself.
Does a rattlesnake add a rattle segment every year?
No, that is a common misconception. A new segment is added each time the snake sheds its skin, and a healthy young rattlesnake in a good season may shed three or four times a year, while an older or slow-growing one sheds less often. Segments also break off regularly, especially in rocky terrain, so the number on the rattle tells you little about age. What the rattle does reliably is make noise; the hollow interlocking segments knock together when the tail muscles buzz, producing the dry warning hiss-buzz that carries for many metres.
What should you do if you meet one on a trail?
Stop, locate the snake, and back away slowly to give it at least a couple of body lengths of space; a diamondback usually rattles precisely so that you will do this. Do not try to move it, kill it, or photograph it up close, as most bites happen when people deliberately interact with the snake. Keep dogs leashed. If someone is bitten, keep them calm and still, remove rings and watches before swelling starts, keep the bitten limb roughly level with the heart, and get to a hospital as fast as possible. Do not cut, suck, apply ice, or use a tourniquet.
Why do people hold rattlesnake roundups?
Roundups are organised events, mainly in Texas and a few other states, where hunters collect large numbers of wild rattlesnakes that are then weighed, milked, butchered, and sold. They began as pest-control and community fundraising events and continue as festivals. Conservationists criticise them for the scale of removal, for the practice of gassing snakes out of dens, which harms many other species that share those refuges, and for spreading fear of an animal that plays an important role controlling rodents. Some former roundups have shifted to catch-and-release wildlife festivals.