An efficient predator of small mammals, birds and lizards, the western diamond-backed rattlesnake hunts by ambush (4), laying in wait around burrows or runs (6). In addition to locating prey by sight and smell, this species also detects body-heat by means of heat-sensitive pits between the eyes and nostrils. When in range, prey is dispatched with a rapid strike, delivering a large quantity of highly toxic venom, which kills the animal within seconds (4). In addition to its toxic effects, the venom also has a role in digestion, and within 24 hours of the prey being ingested, the venom will have broken down the skin and begun to digest the internal organs (7). While the western diamond rattlesnake will usually attempt to escape from potential threats, when cornered, this species will give the characteristic warning rattle, raise its head and the anterior of its body, and may strike if further provoked (4). This species is active during the night in the summer, but extends its activity into the cooler times of day during the spring and autumn (7). During the winter the western diamond-backed rattlesnake undergoes a process analogous to hibernation in mammals, called brumation, in which the low environmental temperatures reduce the snake’s metabolic rate and limit its activity. During this time, the western diamond-backed rattlesnake may form large aggregations in upland areas, which shelter in dens located in abandoned mines, caves, or rock crevices (1) (7).
The western diamond-backed rattlesnake has two breeding periods, the first occurring in the spring, and the second in late summer/autumn. Sperm from the latter period may be stored in the female’s body throughout the winter before being used to fertilise the eggs (8). The western diamond-backed rattlesnake bears live young, and litters may number from 4 to 61 offspring (3). The newborn snakes are well-developed, and already equipped with fangs and toxic venom, but do not reach sexual maturity until three to four years old (4).