Western Diamond-backed Rattlesnake

Crotalus atrox


Venomous-medically significant venom.

Adults are large snakes, commonly ranging from 90-180cm in length with a record length of 223cm, weighing more than 500+ grams. C. atrox is sexually dimorphic in size, with males averaging some 10% longer than females in any given population1. Scales are keeled. Average scale count at midbody is 25. Anal plate is undivided. Color is highly variable in this species; specimens may be gray, tan, red, pink or brown. Pattern consist of a variable number of diamond shape blotches (24-45) along the dorsal surface, with a plain white or cream ventral surface; the pattern may fade towards the posterior of the snake in some cases. The tail is banded in black and white bands of nearly equal length. This combined with a postocular lateral stripe ending prior to the corner of the mouth may be used to distinguish the Western Diamond-backed Rattlesnake from other rattlesnakes in it's range.

Other Common Names

The term coontail rattler is sometimes applied to this snake; confusion can arise as the same common name may be used to refer to the Mojave Rattlesnake.


The is most common in dry to semi-arid lowlands but may occur over 5000 feet. This snake is associated with rock outcrops, desert foothills, shrub covered plains. Does not typically occur in densely wooded habitat.

Natural History

Activity periods are tied to temperature and vary with location; C. atrox in the southern part of their range are active longer than those in the more northerly part of their range, but C. atrox everywhere may be active on any given day provided temperatures are warm enough, with records of activity from March to December in the New Mexico portion of the range. Peak activity varies; Price and LaPointe reported peak acitivty during July and August, but collection records from New Mexico show peak activity seasons in May and August. Crotalus atrox seems to be most active during temperatures in the mid-80s Fahrenheit2 regardless of time. Lifespan is estimated at 10-15 years in the wild.


Crotalus atrox is viviparious. Mating may occur during spring or summer, with young typically being born in July through August. Given that matings have been observed in late August, this raises the possibility of sperm retention. Fitch (1985) reported an average clutch size of 9. Young may be between 22-33cm at birth. Reproductive maturity may be reached at as little as 320 grams and 60cm, typically within three years. Reproduction occurs annually or biennially.


's diet consist mostly of mammals (both by weight and occurrence) as adults, but they may also consume birds and lizards.


' occurs from central Arkansas, south/central Oklahoma, most of Texas, New Mexico and Arizona and into Southern Californa, as well as into northern Mexico.

Meaning of Scientific Name


Krotalon, Greek, rattle


Latin, grim, savage


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