Reproduction, Growth, Survivorship and Activity Patterns in the Southwestern Earless Lizard (Cophosaurus Texanus Scitulus) (Phrynosomatidae) from the Big Bend Region of Texas‪.‬

Abstract. -- This study reports on various aspects of reproduction, growth and survivorship in a population of the southwestern earless lizard, Cophosaurus texanus scitulus, from Big Bend Ranch State Park in west Texas (U.S.A.) over a two year period. Testis enlargement began in mid-April. For females, the earliest presence of oviductal eggs was the first week of June. No females with oviductal eggs were found after 27 August. Yolked follicles were first observed in females collected on 10 April 1998 and 4 April 1999. Egg weight ranged from 13-35% of the total weight of a female with oviductal eggs. Mean clutch sizes ranged from 2.77-4.67 over the two year period. Females collected earlier in the season had larger fat bodies and higher levels of storage lipids. Males had higher growth rates than females in the juvenile-to-yearling age class and in the growth period between yearling and adult. Adult males were significantly larger than females. No bias in the sex ratio was found for any age class in 1998. In 1999, the sex ratio was skewed in favor of yearling males. Survivorship was low for males (juveniles, 12%; yearlings, 29%; adults, 24%) and females (14, 37 and 16%, respectively). Peak periods of activity were between 1000-1159 hr CST. **********