Evaluation of factors associated with predation of broad-snouted caiman (Caiman latirostris)

SIMONCINI, M.; PARACHÚ MARCÓ, M. V.; PORTELINHA, T.; PIÑA, C. I.

Lake Charles

Congreso; XXIII Working Meeting Crocodiles Specialist Group - UICN; 2014

Crocodile Specialist Group (UICN)

Predation is a major cause of crocodilian egg loss. It is reported that predators have the ability to detect preyfrom visual and olfactorysigns. This study aimed to determine the natural predation rate on C. latirostris nests on a normal year (no presence of extreme climatic events), to assess whether olfactory or visual evidences attract predators to caiman nests, and to evaluate the percentage of nests care by females. We searched nests during December/2010 in the northern of Santa Fe province (Argentina) and we assigned the following treatments: control (nests were observed from a distance to avoid disturbances), visual attraction (yellow flagging tapes were tied to vegetation around nests), olfactory attraction (nests were opened, one egg of the clutch was broken, and then the nests were covered again) and olfactory attraction from human disturbance (material was manipulated by researchers without causing any damage to the eggs). We found that the natural predation on broad-snouted caiman nests was approximately 20% in a nesting season. We also observed that olfactory and vision sensory cues were associated with increased predation rates, Human disturbance had astrong association with increased nest predation in terrestrial sites. Female attendance at nests did not decrease the likelihood of predation. To reduce nest predation of broad-snouted caimans, we propose, increasing early search efforts of nests in terrestrial environments relative to those in aquatic environments, avoiding identifying nest sites with highly visual marking, and collecting eggs immediately after they are found.