Assessing the Diet of the Golden eagle (Aquila chrysaetos) and the Biomagnification of Metals by use of Stable isotope analysis and ICP-MS.
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- Institutt for biologi 
Feathers from the golden eagle and muscle tissue from the most important sources of prey (hare, sheep, grouse and reindeer) in the golden eagle diet were analysed for stable isotopes of carbon and nitrogen, and for the heavy metals lead (Pb), cadmium (Cd) and mercury (Hg), and the essential trace elements selenium (Se) and copper (Cu). The samples were obtained from two regions in Central-Norway (Nord-Trøndelag and Sør-Trøndelag), one coastal and one inland region. The Bayesian mixing model MixSIR was used to estimate the proportion of the different prey sources in the diet of the golden eagles. This proportion was used to calculate biomagnification of the selected metals. Regression analysis was used to investigate if there were significant correlations between the metal levels and the proportion of various prey in the diet of golden eagle. The modelled diet of golden eagle varied depending on their age and the region they inhabited. Compared to other studies, metal levels were below harmful levels. Biomagnification were found for Pb and Hg. There were weak significant relationships between the proportion of sheep in the diet of golden eagle, and the levels of Cu and Hg, and the proportion of grouse and levels of Cu. Significant correlations between Se and Hg were found in the eagle feathers and also in the modelled diet of the golden eagle. However, the correlation was weak, and the antagonistic relation between Se and Hg found in many other studies was not evident here. This method is promising for evaluating the diet of the golden eagle. To my knowledge, no similar study has used this approach to assess biomagnification of metals.