Reprodudive charaderistics of the black-tailed brush lizard, <i>Urosaurus nigricaudus</i> (Phrynosomatidae)

Abstract

The reproductive characteristics of Urosaurus nigricaudus al El Comitán, Baja California Sur, México, were deterrnined through the necropsy of 33 males and 60 females during 1992. The average size of clutch per female was 4.06 ± 1.86 eggs; 3.58 eggs for the first c\utch and 4.75 eggs for the second c\utch. Testicular size exhibíts two peaks, one each in May and August. Female and male reproductive cycles are synchronized. In comparison with other Urosaurus species, U. Nigricaudus is atypical because males have two peaks of testicular mass.