Like all rattlesnakes, diamondbacks are not born with a rattle. Instead they begin with just a single button, which soon dries into a tough husk. Each time the snake moults its skin, a new button is left behind by the old skin. The rattle grows in this way until it contains around ten buttons that give the characteristic noise when shaken.
Western diamondbacks have very potent venom. They kill more people each year than any other North American snake, although this number rarely reaches double figures. The venom is extremely effective at tackling prey. It can kill even large prey, such as hares, in seconds. Like other rattlesnakes, diamondbacks can sense body heat using pits on their faces.