Development of follicles and eggs and hormone levels in Caiman latirostris (Crocodylia, Alligatoridae) in Argentina.

PORTELINHA, T.C.G.; JAHN, G.A.; HAPON, M.B.; VERDADE, L.M.; PIÑA, C.I.

Lake Charles

Congreso; 23rd Working Meeting of IUCN-SSC Crocodile Specialist Group; 2014

CSG/IUCN

Despite that there is much information available about Caiman latirostris reproduction, the percentage of adult females actively reproductive over a year is lacking, and this information can help in estimating some population parameters such as population size based on nest counting. In this study we monitored and determined the development of follicles and eggs, and correlated these results with plasma steroid hormone levels in 32 adult females captured in Santa Fe, Argentina. Field work was carried out during two reproductive seasons (October-January) between 2010 and 2012. Using an ultrasound device to take images of the reproductive structures of adult females, we found: vitellogenic follicles (n=5), eggs (n=4), atretic follicles (n=11) and no reproductive structures (n=12). High levels for estradiol were found during ovulation (November). During nesting (December and January) no difference was found in estradiol between reproductive and non-reproductive females. During end of nesting (January) no differences in estradiol were found between reproductive, non-reproductive and females with atretic follicles. There was no difference between progesterone levels for reproductive females during the studied period (October-January), but they showed higher levels during nesting (December) than non-reproductive females. We found no differences in progesterone levels between reproductive females and females with atretic follicles during end of nesting (January). Ultrasound evidenced to be an efficient non-invasive technique to study reproductive structures at the beginning of reproductive cycle of the broad-snouted caiman.