Multi-scale effects of nestling diet on breeding performance in a terrestrial top predator inferred from stable isotope analysis

This is the final version of the article. Available from the publisher via the DOI in this record.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.Funding for this work was provided by projects CGL2007-64805 and CGL2010-17056 from the ‘‘Ministerio de Ciencia e Innovacio´n, Gobierno de Espan˜ a’’, the ‘‘A`rea d’Espais Naturals de la Diputacio´ de Barcelona’’, and Miquel Torres S.A. Fieldwork in France was carried out within the framework of the second National Action Plan for Bonelli’s eagle from the ‘‘Ministe`re franc¸ais de l’E´cologie, de L’E´nergie, du De´veloppement Durable et de la Mer’’ and coordinated by the DREAL LR ‘‘Direction Re´gionale de l’Environnement, de l’Ame´nagement et du Logement-Languedoc-Roussillon’’. J. Resano-Mayor was supported by a predoctoral grant from the ‘‘Departamento de Educacio´n, Gobierno de Navarra; Plan de Formacio´n y de I+D 2008–2009’’, and M. Moleo´n by a postdoctoral grant from the ‘‘Ministerio de Educacio´n, Gobierno de Espan˜ a; Plan Nacional de I+D+i 2008–2011’’. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Análisis de los Cambios Etarios según Sexo en el Borrego de Chiapas

A survey was conducted in order to study changes in body measurements in the Chiapas sheep breed. For this purpose 66 males and 79 females of various ages were measured: body weight, chest girth, knee perimeter, cannon perimeter, coronne perimeter, hock perimeter and ear length. The study reflects a regional change according to age, which are not isometrical. Body weight and chest girth are the most discriminative variables, which presented identical age regression trajectories for both sexes (F=1.006, p=0.317). Although body weight in adult male (>12 months, n=56) was greater than those of females (n=64) (U=1320, p=0.014), and no differences appeared for chest girth (U=1720, p=0.704), regression trajectories for both traits appeared similar.El objetivo del estudio fue la evaluación de los cambios que se producen en diversas medidas corporales en el Borrego Chiapas. Se utilizaron 66 machos y 79 hembras de diversas edades y se registraron las siguientes variables: peso vivo, perímetro torácico, perímetro de la rodilla, perímetro de la caña, perímetro de la corona, perímetro de la rabadilla y longitud de la oreja. El estudio reflejó que hay cambio con la edad diferencial de distintos componentes del cuerpo, en ningún caso isométricos, siendo el peso vivo y el perímetro torácico las variables más discriminativas en el cambio con la edad. Aunque el peso vivo de los machos adultos (>12 meses, n=56) fue mayor que en las hembras (n=64) (U=1320, p=0.014), pero similar en el perímetro torácico (U=1720, p=0.704), las trayectorias de las rectas de regresión de la edad no presentaron diferencias de trayectoria alométrica entre machos y hembras, ni para el peso vivo (F=1.006, p=0.317) ni para el perímetro torácico (F=1.265, p=0.262)