It is also the second largest of North American venomous snakes (the bushmasters, which attain similar weights and greater total length, occur up as far as Nicaragua).

Its postocular stripe is gray or umber and extends diagonally from the lower edge of the eye across the side of the head.

The Mexican west coast rattlesnake (C. basiliscus), also has a mostly dark tail with obscure or absent rings.

The tiger rattlesnake, (C. tigris), has a relatively small head and large rattle along with a dorsal pattern consisting more of crossbands.

The Middle American rattlesnake (C. simus), has a generally uniform gray tail without any rings, as well as a pair of distinctive paravertebral stripes running down the neck.

[2] In the United States, it occurs in central and western Arkansas, Oklahoma excluding the northeast, north-central region and the panhandle, Texas excluding the northern panhandle and the east, southern and central New Mexico and Arizona, extreme southern Nevada, southwestern Utah, and in southeastern California on either side of the Chocolate Mountains.

Frequently roaming during the day, it is common to see the western diamondback when ambient temperatures drop because of the heat retention of blacktop roads.

[14] C. atrox is solitary except during the mating season, when males of the species are single-minded and aggressive in pursuing females.

Usually inactive between late October and early March, these ectotherms occasionally may be seen basking in the sun on warm winter days.

[5] According to Pisani and Stephenson (1991), who conducted a study of the stomach contents of C. atrox in the fall and spring of Oklahoma, mammalian prey included prairie dogs (Cynomys ludovicianus), kangaroo rats (Dipodomys ordii), pocket gophers (Geomys bursarius and Cratogeomys castanops), voles (Microtus ochrogaster), woodrats (Neotoma floridana), pocket mice (Perognathus hispidus and P. flavescens), white-footed mice (Peromyscus leucopus and P. maniculatus), Old World rats and mice (Rattus norvegicus and Mus ssp.

), harvest mice (Reithrodontomys megalotis), fox squirrels (Sciurus niger), cotton rats (Sigmodon hispidus), ground squirrels (Spermophilus spilosoma), rabbits (Sylvilagus floridanus), jackrabbits (Lepus californicus), and an unidentified mole species.

Avian prey include mockingbirds (Mimidae), quail, a nearly full-grown Gambel's quail, a burrowing owl (Athene cunicularia),[6] a fledgling horned lark (Eremophila alpestris) a black-throated sparrow (Amphispiza bilineata), and an eastern meadowlark (Sturnella magna).

Klauber (1972) once found a single specimen in which the stomach contents included grasshoppers, beetles, and ants.

In turn, it is preyed upon by a variety of larger mammals and birds, such as coyotes, foxes, hawks, and owls.

Proteolytic venoms are concentrated secretions that destroy structural tissues and proteins via catabolism, which help in disabling prey.

Microvascular disruption by metalloproteinases also impairs skeletal muscle regeneration, being thereby responsible for fibrosis and permanent tissue loss.

[25] General local effects include pain, heavy internal bleeding, severe swelling, severe muscle damage, bruising, blistering, and necrosis; systemic effects are variable and not specific, but may include headache, nausea, vomiting, abdominal pain, diarrhea, dizziness, and convulsions.

However, the young stay with the mother for only a few hours before they set off on their own to hunt and find cover, so that the mortality rate is very high.

[30] They are also heavily collected from the wild, frequently being drawn out of their hiding places with gasoline and used in rattlesnake roundups, where they are killed for food, skins and entertainment.