engleski

A first investigation of mercury in body feathers of nestling white-tailed eagle Haliaeetus albicilla from Croatia

Nature park Kopački rit is the most important breeding site for white-tailed eagles (Haliaeetus albicilla) in Croatia. The present study therefore investigated the exposure of local eagle nestlings to mercury (Hg), an ubiquitous contaminant well- known to cause toxic effects in apex bird species. Nestling body feathers (n = 72) showed significant variation in Hg concentrations over the studied years (2014 – 2019), with the highest median concentration recorded in 2015 (8.55 µg/g dw). Hg concentrations were not significantly different between sexes, nor between siblings. However, Hg concentrations were found to vary spatially: higher median Hg concentrations were found for nestlings within the active Danube river floodplain (7.46 µg/g dw) compared to those from the former floodplain (3.38 µg/g dw). We expect this to be due to different prey availability: fish, known to be high in Hg content, are less available than terrestrial prey, low in Hg content, in the former floodplain due to extensive drainage works carried out in the past. The stable isotope data will allow us to further shed light on this hypothesis. Finally, the observed Hg concentrations are considered to exceed natural background levels (generally considered to be below 5.00 µg/g dw), warranting continued monitoring of the Hg exposure and its pathways in this population in Kopački rit.

biomonitoring ; dietary pathway ; Hg ; Kopački rit ; non-destructive sampling

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