The Western diamondback rattlesnake is a medium-sized venomous snake found in Northern America. The color pattern od these snakes generally consists of the dusty-looking gray-brown ground color, but it may also be pinkish-brown, brick red, yellowish, pinkish, or chalky white. This ground color is overlaid dorsally with a series of dorsal body blotches that are dark gray-brown to brown in color. Some of the first few blotches may be somewhat rectangular, but then become more hexagonal and eventually take on a distinctive diamond shape, hence the name "diamondback rattlesnake". The tail has two to eight black bands separated by ash white or pale gray interspaces; this led to the nickname of "coon tail".
Western diamondback rattlesnakes are found in the United States from central Arkansas to southeastern and Central California, south into Mexico as far as northern Sinaloa, Hidalgo and northern Veracruz. In the United States, they occur in central and western Arkansas, Oklahoma, Texas, southern and central New Mexico and Arizona, extreme southern Nevada, southwestern Utah, and in southeastern California on either side of the Chocolate Mountains. In Mexico, they occur in Nuevo León, Coahuila, Chihuahua, Sonora, extreme northeastern Baja California, northern Sinaloa, northeastern Durango, Zacatecas, most of San Luis Potosí, northern Veracruz, Hidalgo, and Querétaro. These snakes have also been reported on a number of islands in the Gulf of California, including San Pedro Mártir, Santa María (Sinaloa), Tíburon and the Turner Islands. Western diamondback rattlesnakes live in different habitats that range from flat coastal plains to steep rocky canyons and hillsides; they are associated with many different vegetation types, including desert, sandy creosote areas, mesquite grassland, desert scrub, and pine-oak forests.
Western diamondback rattlesnakes are generally solitary creatures. Usually inactive between late October and early March, these snakes occasionally may be seen basking in the sun on warm winter days. They can be active at any time of the day or night when conditions are favorable. They are primarily diurnal and crepuscular in spring and fall and become nocturnal and crepuscular during the hot summer months. These snakes hunt mainly at night or in the early morning. In the winter, they hibernate or brumate in caves or burrows, sometimes with many other species of snakes. Western diamondbacks are poor climbers. When threatened, they usually coil and rattle to warn aggressors. They are one of the more aggressive rattlesnake species in the US in the way that they stand their ground when confronted by a foe. If rattling does not work, then the snake will strike in defense.
Western diamondback rattlesnakes are carnivores. They feed on small mammals such as chipmunks, prairie dogs, voles, woodrats, rabbits, ground squirrels and also birds, lizards, and even fish.
Western diamondback rattlesnakes usually mate during the fall. They are viviparous meaning that females give birth to live young. Gestation lasts 6 or 7 months and broods average 10 to 25 young. The snakelets are fully-developed and capable of delivering a venomous bite from the moment they are born. They stay with the mother for only a few hours before they set off on their own to hunt and find cover. Western diamondbacks become reproductively mature when they are 3 years old.
There are no major threats to Western diamondback rattlesnakes. However, they do suffer locally from habitat destruction and roadkill. They are also heavily collected from the wild, frequently being drawn out of their hiding places with gasoline and used in rattlesnake roundups (rattlesnake rodeos), where they are killed for food, skins, and entertainment.
According to IUCN, the Western diamondback rattlesnake is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers are stable.
Key participants in the food chain, Western diamondbacks are important predators of many small rodents, rabbits, and birds. In turn, they are preyed upon by a variety of larger mammals and birds, such as coyotes, foxes, hawks, and owls.