Comparative foraging ecology and ecological niche of a superabundant tropical seabird: the sooty tern Sterna fuscata in the southwest Indian Ocean

Abstract : Over 6-million pairs of sooty terns Sterna fuscata breed once a year in the southwest Indian Ocean, mostly on three islands of the Mozambique Channel (Europa, Juan de Nova and Glorieuses) and in the Seychelles region. Seasonal reproduction in either winter or summer is the dominant strategy in the area, but nonseasonal reproduction also occurred in some places like at Glorieuses Archipelago. The feeding ecology of the sooty tern was investigated during the breeding seasons to determine whether terns showed signiWcant diVerences in their trophic ecology between locations. Regurgitations were analyzed to describe the diet of individuals when breeding, and stable isotopes and mercury concentrations were used to temporally integrate over the medium-term of the trophic ecology of both adults and chicks. Overall, the diet was composed of Wsh, Xying squid and Wsh larvae in diVerent proportions. At Europa and Aride in the Seychelles, where winter reproduction occurs, large epipelagic prey like Xying Wsh or squid dominated the diet. At Juan de Nova, sooty terns reproduce in summer and rely mostly on Wsh larvae. At Glorieuses (non-seasonal breeding), the diet was intermediate with Wsh larvae and Xying squid being important prey items. The stable-carbon and nitrogen isotope values in blood conWrm the diVerences observed in dietary analysis, and demonstrate diVerent feeding strategies between colonies. 13C values of feathers showed spatial segregation between birds from the Mozambique Channel and the Seychelles region. Terns from the Seychelles had also higher 15N values. Feather 13C values also suggest a signiWcant shift from summer to wintering habitat for birds from Juan de Nova. This study emphasizes the high phenotypic plasticity of the species, which may explain its numerical dominance in all tropical waters of the World's Ocean.
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https://hal.archives-ouvertes.fr/hal-00322620
Contributeur : Martine Lacalle <>
Soumis le : jeudi 18 septembre 2008 - 11:32:21
Dernière modification le : jeudi 9 février 2017 - 16:58:44

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Sébastien Jaquemet, M. Potier, Yves Cherel, Jessica Kojadinovic, P. Bustamante, et al.. Comparative foraging ecology and ecological niche of a superabundant tropical seabird: the sooty tern Sterna fuscata in the southwest Indian Ocean. Marine Biology, Springer Verlag, 2008, 155, pp.505-520. <10.1007/s00227-008-1049-1>. <hal-00322620>

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