Reproductive tissue was examined from 46 sexually mature female Crotalus atrox specimens from Arizona, and additional data were obtained from gravid females held in the laboratory and from palpation of live snakes in the field.
The western diamond-backed rattlesnake, Crotalus atrox, ranges from southeast California to Arkansas and eastern Texas, Arizona, New Mexico and Oklahoma, south to northern Sinaloa and San Luis Potosi, Mexico (Stebbins 1985).
Table 2 Litter sizes for 29 Crotalus atrox females from Arizona.
Similar testicular cycles may also occur in Crotalus scutulatus in which spermiogenesis takes place in July-August and Crotalus atrox in which spermiogenesis takes place in August-September (Jacob et al.
Biennial reproductive cycles have been reported for other North American rattlesnakes: Rahn (1942) for Crotalus viridis, Tinkle (1962) for Crotalus atrox and Goldberg (1999) for Crotalus tigris.