Walter E. Rhodes

The relation between natural nest temperatures and hatchling sex ratios of American alligator (Alligator mississippiensis) has not been determined adequately. The few studies to date have been limited by study design, low sample size, and inadequate equipment. We investigated this relationship in 20 nests in impoundment habitat in South Carolina during 1995. Actual sex ratios were highly correlated (r = 0.971, P < 0.001) with sex ratios predicted from laboratory results, on the basis of mean nest temperatures between days 30-45 of incubation (temperature-sensitive period (TSP)). Mean...

In American alligators (Alligator mississippiensis), sex determination is dependent upon incubation temperature of the egg prior to hatching. Information about hatchling alligator sex ratios is equivocal, however. Moreover, numerous surveys of juveniles and adults show a male-biased ratio, although a female-biased ratio has been reported for hatchlings from Louisiana. We outline a technique for estimating sex ratios in naturally-incubated alligator nests, and present the initial results from impoundment habitats in South Carolina. In 1994, we located 33 nests and sexed and released 778...