Western diamondback rattlesnake
A big desert rattlesnake with diamond shapes down its back and a black-and-white "coon tail," most likely to be sunning near a trail at Big Bend or Saguaro.
Western diamondback rattlesnake at a glance
Crotalus atrox RAT-ul-snayk; Crotalus atrox is KROT-uh-lus AY-troks
- Type
- Reptile · snake
- Diet
- Carnivore
- Size
- A grown western diamondback is usually about 3 to 4 feet long, close to the length of a baseball bat, and the biggest ones pass 5 feet. It is the largest rattlesnake in the western United States.
- Lifespan
- Around 20 years in the wild.
- Conservation
- Least concern
Eats mice, rats, ground squirrels, rabbits, birds, lizards
It hunts by ambush, waiting still along a rodent trail and sensing a warm animal with pits on its face, then striking fast. Venom flows through hollow fangs, and the snake follows the scent to its meal.
Should you worry?
This snake is venomous, so treat it with respect, not fear. It does not chase people. Almost every bite happens when someone tries to touch, catch, or kill one. Stay on the trail, watch where you put your hands and feet on warm rocks, and if you hear a buzzing rattle, stop, find the snake, and back away slowly. Give it plenty of room and it will let you pass.
The first thing most people meet is the sound: a dry, buzzing rattle from somewhere in the rocks, and then the work of finding the snake it belongs to. A western diamondback is usually about three to four feet long, close to a baseball bat, with diamond shapes down its back and a tail banded black and white like a raccoon’s. That banded tail is why people call it the “coon-tail rattler.” It is the largest rattlesnake in the western United States, and at Big Bend it is the park’s most common one.
The rattle itself is made of loose, dry rings of the same material as your fingernails, and the snake adds a ring every time it sheds its skin. A longer rattle does not mean an older snake, only one that has shed more often. The snake hunts by waiting rather than chasing: it lies still along a trail where mice and rats pass, senses a warm body with the heat-sensing pits on its face, and strikes about half its own length in the time it takes to blink. Venom runs through two hollow fangs, and the snake follows the scent to where its meal has gone.
The snake is venomous, which is a reason for respect, not panic. It does not come after people, and almost every bite happens when someone tries to touch, catch, or kill one. The rules are short. Stay on the trail, watch where you put your hands and feet on warm rocks, and if you hear that buzz, stop, find the snake, and step back the way you came. Give it room and it lets you pass.
Did you know?
- The rattle is made of loose, dry rings of the same stuff as your fingernails. The snake adds a new ring each time it sheds its skin, so a longer rattle does not mean the snake is older by years, just that it has shed more often.
- A rattlesnake can strike about half its own body length in a blink, but it can also stay coiled and silent, so the buzzing rattle is really a warning that means "you are too close."
- The black-and-white bands right above the rattle give this snake its nickname, the "coon-tail rattler," because the tail looks a little like a raccoon's.
Common questions
Are western diamondback rattlesnakes dangerous to kids?
They are venomous, so yes, but they do not hunt or chase people. Stay on the trail, never touch one, and back away if you hear a rattle. Almost all bites happen when someone bothers the snake.
What do I do if I hear a rattle?
Stop walking, look around to find the snake, then slowly step back the way you came. Give it at least a few big steps of room and walk around it.
What do rattlesnakes eat?
Mostly mice, rats, ground squirrels, and rabbits. By eating so many rodents, they help keep the desert in balance.
Can you tell a rattlesnake's age from its rattle?
No. The snake adds a rattle ring every time it sheds, and it can shed a few times a year, so the rattle counts sheds, not birthdays.