CICYTTP   12500
CENTRO DE INVESTIGACION CIENTIFICA Y DE TRANSFERENCIA TECNOLOGICA A LA PRODUCCION
Unidad Ejecutora - UE
artículos
Título:
Evaluation of factors associated with predation on Caiman latirostris nests (Crocodylia: Alligatoridae) in Argentina
Autor/es:
PORTELINHA, T.C.; SIMONCINI, M.; PIÑA, C.I.; PARACHÚ MARCÓ, M.V.
Revista:
PHYLLOMEDUSA
Editorial:
ESALQ/USP
Referencias:
Lugar: Piracicaba; Año: 2016 vol. 15 p. 137 - 146
ISSN:
1519-1397
Resumen:
Evaluation of factors associated with predation on Caiman latirostris nests (Crocodylia: Alligatoridae). Predation is a major cause of crocodilian egg loss. However, at present the mechanism by which predators detect nests is unknown. Previous studies have reported that predators have the ability to detect prey using both visual and olfactory cues. This study aimed to determine the natural predation rate on Broad-snouted caiman (Caiman latirostris) nests in a "normal" year (no extreme climatic events), to assess whether olfactory or visual cues attract predators to caiman nests, and to evaluate the effect of maternal presence on nest predation. During December 2010, we searched for nests in the north of Santa Fe Province, Argentina. Each nest was assigned to one of the following treatments: 1) control nests -nests were observed from a distance to avoid disturbances, 2) visual attraction nests -yellow flagging tapes were tied to vegetation around the nests, 3) olfactory attraction nests -nests were opened, one egg from the clutch was broken, and then the nests were covered again, 4) olfactory attraction from human disturbance -material was manipulated by researchers. We found that, in the absence of extreme climatic events, the natural predation rate on broad-snouted caiman nests was 21% over the nesting season. We also observed that olfactory and visual cues were associated with increased predation rates, and human disturbance had a strong association with increased nest predation in terrestrial sites. Predation rates were less at nests attended by alligators. Management programs that harvest eggs in wild populations (ranching) are based on the concept that removal of a certain proportion of eggs is sustainable because some will be lost to natural causes (predation and flooding) and remaining hatchlings will have improved survival rates. To reduce nest predation of broad-snouted caimans between when the nest is found and when the eggs are collected, we propose avoiding identifying nest sites with highly visible markings (i.e. flagging tapes were tied to vegetation around nests), and collecting eggs immediately after they are found.