Reproduction in the Mojave rattlesnake, Crotalus scutulatus (Serpentes : Viperidae)

Reproductive tissue was examined from 145 museum specimens of Crotalus scut ulatus from Arizona, New Mexico, Texas and Mexico. Males follow a seasonal testicular cycle with sperm produced June-September; regressed testes were present March-May and October. Recrudescence occurred March-July. Timing of this cycle is similar to that of several other North American rattlesnakes . Sperm was present in the vasa deferentia March-October suggesting C. scut ulatus has potential for breeding throughout this period. Females appear to have a biennial reproductive cycle with yolk deposition completed over two activity seasons. Mean litter size for 35 C. scutulatus was 8.2 +/- 2.36 S D, range 5-13 young. Yearly percentages of gravid females appear to be rela ted to food abundance.