Reproduction in the Collared Lizard, Crotaphytus collaris, in West Central Texas

The reproductive cycle of Crotaphytus collaris was studied near San Angelo, Texas. Based on 202 female and 53 male specimens, reproductive activity was observed from April into July with mating likely occurring from April-June during the period of maximum testis size. Females mature in their first reproductive season at about 70 mm snout-vent length. Females, two years old and older, produce two clutches, nine eggs in late April or early May and seven eggs in late May orJune. A third clutch may occasionally be produced in July. Yearling females produce at least one clutch of about five eggs and may occasionally produce a second clutch of similar size. Except for extreme northern populations, there appears to be little geographic variation in reproduction in C. collaris.