Marine Biology

, Volume 157, Issue 11, pp 2453–2459

Age and sexual differences in the exploitation of two anthropogenic food resources for an opportunistic seabird

  • Joan Navarro
  • Daniel Oro
  • Albert Bertolero
  • Meritxell Genovart
  • Antonio Delgado
  • Manuela G. Forero
Original Paper

DOI: 10.1007/s00227-010-1509-2

Cite this article as:
Navarro, J., Oro, D., Bertolero, A. et al. Mar Biol (2010) 157: 2453. doi:10.1007/s00227-010-1509-2

Abstract

The availability of food resources has been suggested as a major factor in the substantial increase in reproductive output, survival, recruitment and, ultimately, population growth rates in most organisms. In fact, the artificial increase in food availability resulting from human activities has been suggested as a factor in the substantial increase in population size of several seabirds in recent decades. In the present study, our primary aim was to estimate the importance of the main natural prey and two alternative feeding resources, fishery discards and the invasive American crayfish Procambarus clarkii, for an opportunistic seabird, the Audouin’s gull Larus audouinii. We also assessed the influence of age and sex in the use of those three types of food. For this purpose, we compared the analyses of δ15N and δ13C in blood of male and female adults of known age and chicks with those in their potential prey. Our results reveal sex-related and age-related differences in the consumption of fish discards, small pelagic fish and American crayfish. Differences in the diet of males and females and also between adults and chicks could be related to different nutritional requirements. Age differences were probably related to their different foraging proficiency and the tendency of young breeders to opportunistically exploit anthropogenically derived food. This study illustrates the importance of considering the age and sex of individuals to obtain feasible dietary information and to understand how the exploitation of food of human origin could affect population growth.

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Joan Navarro
    • 1
    • 5
  • Daniel Oro
    • 2
  • Albert Bertolero
    • 3
  • Meritxell Genovart
    • 2
  • Antonio Delgado
    • 4
  • Manuela G. Forero
    • 1
  1. 1.Department of Conservation BiologyEstación Biológica de Doñana, CSICSevillaSpain
  2. 2.Institut Mediterrani d’Estudis Avançats, IMEDEA (CSIC-UIB)Esporles, MajorcaSpain
  3. 3.IRTA Ecosistemes Aquàtics, Sant Carles de la RàpitaSant Carles de la RàpitaSpain
  4. 4.Laboratorio de Biogeoquímica de Isótopos EstablesInstituio Andaluz de Ciencias de la Tierra, CSICArmilla, GranadaSpain
  5. 5.Institute of Marine Science (ICM-CSIC)BarcelonaSpain

Personalised recommendations