title: Multi-scale effects of nestling diet on breeding performance in a terrestrial top predator inferred from stable isotope analysis.
abstract: Inter-individual diet variation within populations is likely to have important ecological and evolutionary implications. The diet-fitness relationships at the individual level and the emerging population processes are, however, poorly understood for most avian predators inhabiting complex terrestrial ecosystems. In this study, we use an isotopic approach to assess the trophic ecology of nestlings in a long-lived raptor, the Bonelli's eagle Aquila fasciata, and investigate whether nestling dietary breath and main prey consumption can affect the species' reproductive performance at two spatial scales: territories within populations and populations over a large geographic area. At the territory level, those breeding pairs whose nestlings consumed similar diets to the overall population (i.e. moderate consumption of preferred prey, but complemented by alternative prey categories) or those disproportionally consuming preferred prey were more likely to fledge two chicks. An increase in the diet diversity, however, related negatively with productivity. The age and replacements of breeding pair members had also an influence on productivity, with more fledglings associated to adult pairs with few replacements, as expected in long-lived species. At the population level, mean productivity was higher in those population-years with lower dietary breadth and higher diet similarity among territories, which was related to an overall higher consumption of preferred prey. Thus, we revealed a correspondence in diet-fitness relationships at two spatial scales: territories and populations. We suggest that stable isotope analyses may be a powerful tool to monitor the diet of terrestrial avian predators on large spatio-temporal scales, which could serve to detect potential changes in the availability of those prey on which predators depend for breeding. We encourage ecologists and evolutionary and conservation biologists concerned with the multi-scale fitness consequences of inter-individual variation in resource use to employ similar stable isotope-based approaches, which can be successfully applied to complex ecosystems such as the Mediterranean.
authors.affiliation: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Resano-Mayor
authors.affiliation: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Hernández-Matías
authors.affiliation: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Real
authors.affiliation: Departamento de Biología Aplicada, Universidad Miguel Hernández, Orihuela, Alicante, Spain.
authors.forename: Marcos
authors.initials: M
authors.lastname: Moleón
authors.affiliation: Equip de Biologia de la Conservació, Departament de Biologia Animal, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Parés
authors.affiliation: Environment and Sustainability Institute, University of Exeter, Cornwall Campus, Penryn, Cornwall, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Inger
authors.affiliation: Centre for Ecology and Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, United Kingdom.
authors.forename: Stuart
authors.initials: S
authors.lastname: Bearhop
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology; D001947:Breeding; D004032:Diet; D007554:Isotopes / Q000032:analysis*; D011235:Predatory Behavior / Q000502:physiology*; D020304:Raptors / Q000502:physiology
chemical_list: D007554:Isotopes
references.citation: Ecology. 2011 Aug;92(8):1582-93
references.pmid: 21905425
references.citation: J Anim Ecol. 2012 Nov;81(6):1154-1160
references.pmid: 22676770
references.citation: Proc Biol Sci. 2007 Mar 22;274(1611):839-44
references.pmid: 17251094
references.citation: J Anim Ecol. 2011 Jul;80(4):896-903
references.pmid: 21644976
references.citation: Trends Ecol Evol. 1995 Sep;10(9):374-8
references.pmid: 21237076
references.citation: Am Nat. 2003 Jan;161(1):1-28
references.pmid: 12650459
references.citation: PLoS One. 2011;6(7):e22851
references.pmid: 21818399
references.citation: Ecology. 2007 Jan;88(1):42-8
references.pmid: 17489452
references.citation: Ecol Lett. 2009 Mar;12(3):E1-5
references.pmid: 18691222
references.citation: Ecol Lett. 2011 Sep;14(9):948-58
references.pmid: 21790933
references.citation: J Anim Ecol. 2009 Mar;78(2):460-7
references.pmid: 19021778
references.citation: Oecologia. 1990 Jul;83(4):443-451
references.pmid: 28313176
references.citation: J Anim Ecol. 2009 Jul;78(4):848-56
references.pmid: 19486381
references.citation: Ecol Lett. 2008 May;11(5):470-80
references.pmid: 18294213
references.citation: PLoS One. 2008 Jun 04;3(6):e2307
references.pmid: 18523587
references.citation: Oecologia. 2012 Mar;168(3):679-89
references.pmid: 21947548
references.citation: Ecology. 2009 Aug;90(8):2263-74
references.pmid: 19739388
references.citation: PLoS One. 2010 Mar 12;5(3):e9672
references.pmid: 20300637
references.citation: J Wildl Dis. 2000 Jan;36(1):64-70
references.pmid: 10682745
references.citation: J Anim Ecol. 2010 Sep;79(5):974-82
references.pmid: 20579179
references.citation: Ecology. 2013 Mar;94(3):565-72
references.pmid: 23687882
references.citation: J Anim Ecol. 2008 Nov;77(6):1082-91
references.pmid: 18624834
references.citation: J Anim Ecol. 2011 May;80(3):595-602
references.pmid: 21401589
references.citation: J Anim Ecol. 2012 Mar;81(2):330-40
references.pmid: 21950339
references.citation: Ecol Evol. 2013 Sep;3(9):2867-79
references.pmid: 24101979
references.citation: Ecol Lett. 2012 May;15(5):475-83
references.pmid: 22414160
references.citation: PLoS One. 2012;7(2):e31757
references.pmid: 22363724