Sexual identification of Caiman latirostris hatchlings by cloacal inspection

CIOCAN, H; LEIVA, P.; SIMONCINI, M.; PIÑA, C. I.

Santa Fe

Congreso; XXV Working Meeting Crocodiles Specialist Group - UICN.; 2018

Crocodile Specialist Group/IUCN

Sexual identification of crocodilians is important in population studies. This informationis also useful when preparing or proposing conservation and management plans, as wellas monitoring these populations over time. In nature, it is possible to differentiate malesand females of Caiman latirostris, by cloacal palpation or eversion of the penis inindividuals larger than 75cm in total length; but smaller animals show a hardlydifferentiable cliteropene. In neonates, sex determination methods involve surgical examinations, necropsies or analysis of cranial dimorphism, which are not applicable tofield sampling conditions. In this work, we classified hatchlings of C. latirostris,observing the color and shape of their genitals. We were able to characterize penis as amilky white organ with a rounded shape at the tip and a purple hue at the end; whileclitoris is shorter, whitish and with a pointed end. The procedure was tested onhatchlings from 3 nests, half of the eggs of each nest were incubated at a constanttemperature of 31°C (producer of females) and the other half at 33°C (producer ofmales). After the observation and classification into males or females, the sex of theanimals was verified by direct gonads observation and histology. According to ourobservations, in the first days of life we correctly assigned the sex of 80% of theindividuals of C. latirostris, but it was observed that misclassification decreased asanimal size increased. It should be mentioned that the number of correct identificationswas slightly lower for males than for females. We correctly classified the sex in 100%of the cases when the caiman reached a total length of 36cm. This technique would be auseful tool for field studies, for making it possible to estimate the sex of small offspringin situ.