Western Diamondback Rattlesnake
These venomous snakes - so-called because of the rattling sound they give as a warning before striking - remain numerous despite widespread persecution. Western diamondbacks are the largest and most venomous rattlesnakes in North America. This particular species is one of the boldest and most aggressive of all rattlesnakes. The snake's rattle comprises dried segments, or buttons, of skin attached to the tail. The rattle is used to warn predators that the snake gives a poisonous bite. Although it will readily defend itself when cornered, the diamondback would prefer to conserve venom, and enemies, including humans, soon learn to associate the rattle with danger.
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.
Diamondbacks are so named because of the brown diamonds, bordered with cream scales, seen along their backs.
Western diamondbacks have a very potent venom. They kill more people each year than any other North American snake, although this number rarely reaches double figures. The venom can kill even large prey, such as hares, in seconds. Like other rattlesnakes, diamondbacks can sense body heat using sensory pits on their faces.
They hunt at night during the summer and hibernate throughout the winter, although they sometimes emerge on warmer winter days. These snakes retreat into caves or share the burrows of other creatures at this time of year. Although adaptable in terms of their prey, western diamondback rattlesnakes are able to survive for up to two years without eating if necessary, thanks to their stores of body fat.
Distribution: Extends from California, offshore islands and central Arkansas in the USA, southwards into Mexico, to northern parts of Sinaloa and Veracruz, as well as Hidalgo.
Habitat: Grassland and rocky country.
Weight: Average 6.8 kg (15 lb), but can be up to 10.4 kg (23 lb); males larger.
Length: Average 1.2 m (4 ft), but has reached 2.13 m (7 ft).
Maturity: 2 - 3 years Gestation Period 6-7 months.
Breeding: About 12; they disperse shortly after birth, already venomous.
Food: Mainly small mammals, especially rodents and rabbits, plus some birds and lizards.
Lifespan: Up to 22 years.
Status: Lower risk.
This extends diagonally across the cheeks from below each eye.
The pattern on the back explains their alternate name of western diamondback.
Formed by modified scales at the tip of the tail, the rattle gets larger as the snake ages.
These are very evident in these snakes, irrespective of their underlying colouration.
A rattlesnake may rest curled up in the open, but, if disturbed, it adopts a much more menacing posture, with its head raised to strike.
Mating occurs in spring, and as with other snakes, the male's copulatory organ is divided into two parts, called hemipenes.