Black caiman; Stable isotopes; Dietary ecology; Movement; French Guiana
Abstract :
[en] The black caiman is one of the largest neotropical top predators, which means that it could play a structuring role within swamp ecosystems. However, because of the difficulties inherent to studying black caimans, data are sorely lacking on many aspects of their general biology, natural history, and ecology, especially in French Guiana. We conducted a detailed study of the Agami Pond black caiman population using a multidisciplinary approach. The aim was to better understand the species’ dietary ecology and movements in the pond, and thus its functional role in pond system. We gathered natural history data, tracked caiman movements using satellite transmitters, and characterized feeding ecology via stable isotope analysis. Our study was carried out over three sampling periods and spanned both wet and dry seasons, which differ in their hydrological and ecological conditions. Our results show that black caiman abundance and age demographics differed between seasons in Agami Pond. In the dry season, Agami Pond is one of the only areas within the marsh to hold water. It thus contains large quantities of different fish species, which form the basis of the black caiman’s diet. Caiman body size, a proxy for age class, was around 1.5 meters. During the wet season, which corresponds to the breeding period for migratory birds (e.g., Agami herons), adult black caimans are present in Agami Pond. Adults were most abundant in the inundated forest. There, most individuals measured up to 2 meters. They also exhibited a particular “predatory” behavior near bird nests, preying on fallen chicks and adults. Juveniles and subadults were present during both seasons in the pond’s open waters. These behavioral observations were backed up by stable isotope analysis, which revealed ontogenetic variation in the caiman’s isotopic values. This isotopic variation reflected variation in diet that likely reduced intraspecific competition between adults and young. The telemetry and microchip data show that different age classes had different movement patterns and that seasonal variation in the pond may influence caiman prey availability and reproductive behavior. The new information gathered should help predict this species’ responses to potential ecosystem disturbance (e.g., water pollution, habitat destruction) and inform the development of an effective conservation plan that involves locals and wildlife officials.
Caut, Stephane; Consejo Superior de Investigaciones Cientificas & ANIMAVEG Conservation > Departamento de Etologia y Conservacion de la Biodiversidad, Estacion Biologica de Doñana
Francois, Vincent; Alligator Bay
Bacques, Matthieu; ANIMAVEG Conservation
Guiral, Daniel; Institut de Recherche pour le Développement & Aix-Marseille Université > Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale
Lemaire, Jérémy; Centre d’études Biologiques de Chizé, CEBC UMR 7372 CNRS-Université de La Rochelle
Lepoint, Gilles ; Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Océanographie biologique
Marquis, Olivier; MNHN & Parc Zoologique de Paris
Sturaro, Nicolas ; Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Océanographie biologique
Language :
English
Title :
The dark side of the black caiman: Shedding light on species dietary ecology and movement in Agami Pond, French Guiana
Publication date :
24 June 2019
Journal title :
PLoS ONE
eISSN :
1932-6203
Volume :
14
Issue :
6
Pages :
e0217239
Peer reviewed :
Peer reviewed
Funders :
Consejo Superior de Investigaciones Cientıficas (CSIC) research contracts to SC and the Estacion Biologica de Donana Paris Zoological Park Fonds de Dotation pour la Biodiversity and the private company Lacoste National Geographic Society / Waitt Grants Program (#W269-13) La Ferme aux Crocodiles Zoological Park
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