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Spatial variation in the foraging behaviour of the Galapagos sea lions (Zalophus wollebaeki) assessed using scat collections and stable isotope analysis

Published online by Cambridge University Press:  03 December 2013

Diego Páez-Rosas  and
David Aurioles-Gamboa
Diego Páez-Rosas*
Affiliation:
Universidad San Francisco de Quito (USFQ) and Galapagos Science Center, Galapagos, Ecuador Programa PROMETEO-SENESCYT, Secretaria Nacional de Educación Superior, Ciencia, Tecnología e Innovación Quito, Ecuador Parque Nacional Galápagos, Unidad Técnica San Cristóbal, Islas Galápagos, Ecuador
David Aurioles-Gamboa
Affiliation:
Laboratorio de Ecología de Pinnípedos “Burney J. Le Boeuf”, Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional, La Paz, B.C.S., México
*
Correspondence shold be addressed to: Diego Páez-Rosas, Universidad San Francisco de Quito, Av. Alsacio Northia s/n, frente Playa Mann, Isla San Cristóbal, Galapagos, Ecuador email: dpaez@usfq.edu.ec.
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Abstract

This study focuses on the comparative analysis of variables related to the trophic niche plasticity in the Galapagos sea lion (Zalophus wollebaeki). There is great concern regarding the future of this species, so study of the diet and the way these animals obtain their food is useful to understand and predict their survival possibilities in the long term. The combined use of scat analysis and stable isotopes helps to determine foraging habits of this species in greater detail. The objective of the study was to assess the feeding habits of Z. wollebaeki and its space–time variation. The scat analysis (n = 200) gave as a result space–time changes in the foraging strategies of this species. The isotopic values (n = 80) showed differences in relation to foraging grounds (δ13C: P = 0.001), but also suggested an apparent stability in the trophic level of their diet (δ15N: P = 0.084). These results constitute a relevant finding in the evolutionary behaviour of the species, showing that Z. wollebaeki has developed a high degree of plasticity in its foraging habits that may improve its survival in a highly demanding ecosystem in terms of limited and fluctuating resources.

Keywords

foraging behaviourtrophic nichescat analysisstable isotopesGalapagos IslandsZalophus wollebaeki
Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 94 , Issue 6 , September 2014 , pp. 1099 - 1107
Copyright
Copyright © Marine Biological Association of the United Kingdom 2013 

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