Using Stable Isotopes To Determine Dietary Patterns In Bonelli's Eagle (Aquila fasciata) Nestlings

Resano, Jaime; Hernández‐Matías, Antonio; Real, Joan; Parés, Francesc

doi:10.3356/jrr-11-13.1

Cited by 18 publications

(11 citation statements)

References 48 publications

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“…Our results therefore suggest that both pellet analysis and SIAR are suitable methods to assess the diet of avian predators at the population level (Real , Resano et al . ). At the territory level, we also found broad agreement in the relative rankings of prey consumption rates; that is, the most‐consumed prey as assessed by pellet analysis was the same prey category identified as most‐consumed by SIAR, and similarly for the least‐consumed prey category (Fig.…”

Section: Discussionmentioning

confidence: 97%

“…Isotopic measurements of both prey and nestlings were performed at the Scientific and Technological Centres of the University of Barcelona using the methods of Resano et al . ().…”

Section: Methodsmentioning

confidence: 97%

“…More recently, an isotopic approach showed that δ 13 C, δ 15 N and δ 34 S are useful to assess both terrestrial and marine prey consumption of Bonelli's Eagle nestlings (Resano et al . ). Consequently, this species is a suitable model to test whether conventional diet analysis and isotopic mixing models provide similar information when assessing the diet of avian predators.…”

mentioning

confidence: 97%

“…The diet of Bonelli's Eagle in the Mediterranean has been widely studied by conventional methods, showing that the species mainly predates European Rabbits Oryctolagus cuniculus, partridges Alectoris spp., pigeons Columba spp., passerines (mainly corvids and thrushes) and lizards (Real 1991, Mole on et al 2009). More recently, an isotopic approach showed that d 13 C, d 15 N and d 34 S are useful to assess both terrestrial and marine prey consumption of Bonelli's Eagle nestlings (Resano et al 2011). Consequently, this species is a suitable model to test whether conventional diet analysis and isotopic mixing models provide similar information when assessing the diet of avian predators.…”

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confidence: 99%

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Comparing pellet and stable isotope analyses of nestling Bonelli's Eagle Aquila fasciata diet

Resano‐Mayor

Hernández‐Matías

Real

et al. 2013

Ibis

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Diet analyses are central to the study of avian trophic ecology, and stable isotope analyses have made an increasing contribution in the last two decades. Few isotopic studies have assessed the diet of raptor species, which are more frequently analysed by conventional diet methods such as pellet analysis. In this study, we compare prey consumption estimates of nestling Bonelli's Eagles Aquila fasciata from conventional pellet analysis (in terms of items and biomass) and stable isotopic mixing models (SIAR) using δ13C, δ15N and δ34S of feathers. The pellet analysis showed that European Rabbits Oryctolagus cuniculus, pigeons (mainly Common Wood Pigeons Columba palumbus and Domestic Pigeons Columba livia dom.), Red‐legged Partridges Alectoris rufa, passerines, Yellow‐legged Gulls Larus michahellis and Eurasian Red Squirrels Sciurus vulgaris were the main prey, so they were selected for diet reconstructions in SIAR. At the population level, mean prey consumption estimates were similar for pellets (both items and biomass) and SIAR. At the territory level, the weighted kappa statistic showed good ordinal scale agreement in main prey consumption between items or biomass and SIAR. Although the intraclass correlation coefficient showed poor method agreement when considering all prey in the same analysis, the intraclass correlation coefficients for each prey category showed significant agreement between pellets and SIAR when estimating the consumption of Rabbits, pigeons and Gulls, with lower agreement for passerines and Squirrels. Lastly, there was poor method agreement for estimates of Partridges. Our results suggest an overall agreement between the pellet analysis and SIAR when estimating nestling Bonelli's Eagle diet at both the population and, to a lesser extent, the territory level, supporting the usefulness of isotopic mixing models when identifying the terrestrial and marine components of raptor diets.

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Section: Discussionmentioning

confidence: 97%

“…Isotopic measurements of both prey and nestlings were performed at the Scientific and Technological Centres of the University of Barcelona using the methods of Resano et al . ().…”

Section: Methodsmentioning

confidence: 97%

mentioning

confidence: 97%

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confidence: 99%

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Comparing pellet and stable isotope analyses of nestling Bonelli's Eagle Aquila fasciata diet

Resano‐Mayor

Hernández‐Matías

Real

et al. 2013

Ibis

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“…The most likely explanation for this previous decline in these populations is that, in the past, the number of immigrants was not sufficient to support the size of the population, as our models suggest. Additionally, it is also possible that environmental conditions in the dispersal areas (where non-territorial eagles are found) have improved in recent years as a result of the concerted efforts to correct dangerous power lines in the main dispersal areas in central (Guil et al 2011) and southern Spain (Gil-Sa´nchez et al 2005, Moleo´n et al 2007) and the recent increase in rabbit numbers (the preferred prey species of this eagle) after their dramatic decline in the 1990s (Delibes-Mateos et al 2007, Moleo´n et al 2009, Resano et al 2011). FIG.…”

Section: Effect Of Uncertainty On Bonelli's Eagle Viability Assessmentmentioning

confidence: 99%

From local monitoring to a broad‐scale viability assessment: a case study for the Bonelli's Eagle in western Europe

Hernández‐Matías

Real

Moleón

et al. 2013

Ecological Monographs

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101

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Abstract. Population viability analysis (PVA) has become a basic tool of current conservation practice. However, if not accounted for properly, the uncertainties inherent to PVA predictions can decrease the reliability of this type of analysis. In the present study, we performed a PVA of the whole western European population (France, Portugal, and Spain) of the endangered Bonelli's Eagle (Aquila fasciata), in which we thoroughly explored the consequences of uncertainty in population processes and parameters on PVA predictions. First, we estimated key vital rates (survival, fertility, recruitment, and dispersal rates) using monitoring, ringing, and bibliographic data from the period 1990-2009 from 12 populations found throughout the studied geographic range. Second, we evaluated the uncertainty about model structure (i.e., the assumed processes that govern individual fates and population dynamics) by comparing the observed growth rates of the studied populations with model predictions for the same period. Third, using the model structures suggested in the previous step, we assessed the viability of both the local populations and the overall population. Finally, we analyzed the effects of model and parameter uncertainty on PVA predictions. Our results strongly support the idea that all local populations in western Europe belong to a single, spatially structured population operating as a sourcesink system, whereby the populations in the south of the Iberian Peninsula act as sources and, thanks to dispersal, sustain all other local populations, which would otherwise decline. Predictions regarding population dynamics varied considerably, and models assuming more constrained dispersal predicted more pessimistic population trends than models assuming greater dispersal. Model predictions accounting for parameter uncertainty revealed a marked increase in the risk of population declines over the next 50 years. Sensitivity analyses indicated that adult and pre-adult survival are the chief vital rates regulating these populations, and thus, the conservation efforts aimed at improving these survival rates should be strengthened in order to guarantee the long-term viability of the European populations of this endangered species. Overall, the study provides a framework for the implementation of multi-site PVAs and highlights the importance of dispersal processes in shaping the population dynamics of long-lived birds distributed across heterogeneous landscapes.

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Conserving the European Bonelli's eagle in spatiotemporal domain: Lesson from its feeding pattern

Upadhyay

2021

Comp and Math Methods

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Bonelli's eagle (Hieraaetus fasciatus), a threatened species in Western Europe, has suffered a critical and severe decline in last two decades. In this article, a qualitative analysis of an ecoepidemiological model which consists of two prey and a predator is carried out. We proposed and designed a spatiotemporal model to predict the distribution of a territorial predator, Bonelli's eagle and its two main prey species (rabbit and red-legged partridge). Bounded positive solution, feasibility of the equilibria, and their stability analysis are determined for the nonspatial counterpart of the system. Criteria for diffusion-driven instability caused by local random movements of rabbits, partridges, and Bonelli's eagle are obtained. Possible implications of the result for Bonelli's eagle conservation are discussed. We show that the inclusion of second prey in the system can drastically change the dynamics from the single prey case. We also found that the presence of a second prey is beneficial for the conservation of the threatened Bonelli's eagle population in Europe. Results obtained from theoretical analysis of the nonspatial model agree very well with the numerical simulation results. Lastly, via numerical simulation, we illustrate the effect of diffusion of the dynamical system in the spatial/spatiotemporal domain by different pattern formations.

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Using Stable Isotopes To Determine Dietary Patterns In Bonelli's Eagle (Aquila fasciata) Nestlings

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 18 publications

References 48 publications

Comparing pellet and stable isotope analyses of nestling Bonelli's Eagle Aquila fasciata diet

Comparing pellet and stable isotope analyses of nestling Bonelli's Eagle Aquila fasciata diet

From local monitoring to a broad‐scale viability assessment: a case study for the Bonelli's Eagle in western Europe

Conserving the European Bonelli's eagle in spatiotemporal domain: Lesson from its feeding pattern

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