Population dynamics of the saxicolous lizard Tropidurus itambere (Tropiduridae) in a seasonal habitat of southeastern Brazil

I studied the population dynamics of Tropidurus itambere in an outcrop form ation in Valinhos, Sao Paulo State, southeastern Brazil. I carried out a ma rk-recapture study on a 1.72 ha grid from February 1993 to January 1995. I estimated density (number of individuals/ha), biomass (g/ha), sex ratio, ag e structure, and the observed population growth rate (r) monthly. Survival (persistence) rates of males and females were estimated between successive reproductive seasons. Density varied seasonally, increasing during the recr uitment period. The observed population growth rates varied monthly and the ir mean value ((r) over bar = 0.015) was positive, though small, suggesting that this population was marginally increasing. The sex ratio of juveniles was 1:1, suggesting there is no between-sex differences in birth rate. Wit hin adults, female-biased sex ratios occurred during the reproductive seaso ns (December-March), and these biases may result from the spacing pattern o f adults in the habitat in these seasons. Survival rates between successive reproductive seasons did not differ statistically between sexes, although survival rates for females (0.35) were higher than for males (0.25).