2015/09/02 by Mirjam Nadjafzadeh, Christian C. Voigt, Oliver Krone · 2 citations
Environmental Science · #Apex predator #Avian ecology and behavior #Biology #Ecological niche #Ecology #Generalist and specialist species #Habitat #Isotope Analysis in Ecology #Isotope analysis #Marine animal studies overview #Niche #Population #Predation #Range (aeronautics) #Stable isotope ratio #Zoology #δ13C
paper · doi:10.1111/ibi.12311
openalex publication_date 2015/09/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/24
Many raptor species are considered to be generalists, taking a range of prey species. However, longitudinal dietary records are often scarce, although necessary for characterizing niche width of species at population and individual levels. Quantifying raptor diets at large spatio‐temporal scales is often necessary for refining conservation efforts, although it can be particularly difficult and may involve a great effort by conventional means. Therefore, we adopted the analysis of stable isotopes in tissues of predators and their potential food sources as a complementary methodology for assessing animals' diet. We examined the isotopic composition ( δ 13 C and δ 15 N) of White‐tailed Eagles Haliaeetus albicilla from Germany, Finland and Greenland to detect patterns of dietary variation and quantify diet composition. The isotopic analysis included liver and muscle samples from Eagles of the three populations together with 16 potential food sources in the German population. Our results suggested dietary differences between German and Greenlandic Eagles, in accordance with the availability of freshwater and marine habitats in each population. Within the German population, we found seasonal shifts in isotopic ratios, suggesting the birds responded to temporal changes in food availabilities, and age‐related isotopic differences, indicating different diets in adults and juveniles. Isotopic values of liver and muscle tissues collected from the same animal showed intra‐individual short‐term changes in the German and Finnish but not Greenlandic population. This suggests that local feeding niches of this generalist predator may vary with local food supplies, which determines the niche width (from generalist to specialist) at the individual level. Our results also revealed that game mammal carcasses constitute an important food source (29.5% of diet) for the German Eagle population during the winter half‐year corresponding to the hunting season. This result is of relevance to management and conservation because the White‐tailed Eagle and other raptor species are affected by the ingestion of lead ammunition from shot mammalian carcasses.