Intraspecific feeding habitats variation in broad-snouted caiman (Caiman latirostris) in Argentina.

PORTELINHA, T.C.G.; MARQUES, T.S.; LARA, N.R.F.; VERDADE, L.M.; CAMARGO, P.B.; PIÑA, C.I.

Lake Charles

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

CSG/IUCN

Wild animals minimize intraspecific competition through maximizing the exploitation of available resources. Crocodilians show a dramatic increase in body mass from hatchling to adult, which results in changes in the exploitation of food resources. Stable isotopes analyses are useful to verify intraspecific variations in feeding habitats because the chemical composition of animals tends to reflect the food consumed. This study aimed to verify the existence of sexual and ontogenetic feeding habitats variation for the broad-snouted caiman (Caiman latirostris) in a stream surrounded by a flooded area in northern Argentina using carbon and nitrogen stable isotopes. Isotopes compositions were determined from claw samples of 34 individuals (14 juveniles: 9♂ and 5♀; and 20 adults: 10♂ and 10♀) collected during field work between October/2010 and January/2012. We found no difference between juveniles and adults for δ13C (J: -20.4 ± 1.1?; A: -21.0 ± 1.3?) and δ15N (J: 7.2 ± 0.9?; A: 6.7 ± 0.5?). We also found no difference between sex inside size class for δ13C (A♀: -20.7 ± 0.8?; A♂: -20.2 ± 1.4?; J♀: -20.5 ± 1.7?; J♂: -21.4 ± 0.9?) and for δ15N (A♀: 7.6 ± 0.8?; A♂: 6.8 ± 0.9?; J♀: 6.9 ± 0.4?; J♂: 6.7 ± 0.7?). Similar values of isotopic compositions could indicate an intraespecific overlap on exploitation of food resources. This could be due to the wide availability of food resources on the study area being capable to support higher population densities.