Temperature variation in nests of Paleosuchus palpebrosus (Crocodylia: Alligatoridae) near the southern edge of the species range, Brazil

Temperature variation in nests of Paleosuchus palpebrosus (Crocodylia: Alligatoridae) near the southern edge of the species range, Brazil. Incubation temperature determines the sex of all crocodilians that have been studied; the maximum proportion of males is usually produced between 31oC and 33 oC, but the temperature that produces the maximum proportion of males varies among and within species. We monitored the temperature of seven Paleosuchus palpebrosus nests found on the banks of streams surrounding the Pantanal, near the southern limit of the species´ distribution, between 2008 and 2013. The mean temperature of the nests between 45 and 68 days incubation, the presumed period of sex determination, varied between 26.1 and 31.5o C. One nest with mean temperature of 30.3oC (SD=0.70) apparently produced at least three males (75% of hatchlings captured), indicating that the female-to-male sex transition may occur at relatively low temperatures in this species at this location.