Ranching programs: does resources exploitation change between wild and reintroduced crocodilians?

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

Ranching programs are a common practice adopted for conservation and sustainable use of crocodilians, such as the Proyecto Yacaré for the broad-snouted caiman (Caiman latirostris) in Argentina. This program reintroduces a percent of hatchlings born and kept in captivity on wild populations after one year. However, knowledge about the behavior of reintroduced individuals such as food resources exploitation is lacking. In this sense, stable isotopes analyses show an interesting tool to answer questions about food web dynamics and trophic ecology. In this study we investigated variation on diet resources exploitation between wild (WD) and reintroduced (RT) females of C. latirostris. Fieldwork was carried out between April/2010 and January/2012 in three study areas (Fisco: stream and lagoon, Espín: stream, and Caminos: stream surrounded by a flooded area) of the pampas in Santa Fe Province, Argentina. We determined isotopes compositions of carbon (δ13C) and nitrogen (δ15N) from claw samples of adult wild (n=23) and reintroduced (n=19) females. We found no difference between wild and reintroduced females for δ13C (Fisco: WD = -21.3 ± 1.0?, RT = -20.8 ± 2.1?; Espín: WD = -21.1 ± 1.6?; RT = -20.4 ± 0.9?; Caminos: WD = -20.7 ± 1.0?, RT = -20.7 ± 0.3?) and δ15N (Fisco: WD = 6.6 ± 0.7?, RT = 6.9 ± 0.7?; Espín: WD = 7.3 ± 0.8?, RT = 7.2 ± 0.8?; Caminos: WD = 7.4 ± 0.9?, RT = 8.0 ± 0.4?). The present results suggest that wild and reintroduced females exploit food resources in a similar way.