Feathers of white stork Ciconia ciconia chicks in North‐Eastern Greece, as indicators of geographical variation in mercury contamination

Abstract

Variations in mercury contamination of ecosystems were assessed among areas of northeast Greece by sampling and analysing feathers of White Stork chicks. Mercury concentrations in stork chick feathers were highest in an area known to be affected by riverborne mercury pollution, and were lowest in an inland area away from rivers or lakes. Although regurgitated pellets indicated a predominantly terrestrial diet among White Stork adults, variation in mercury concentrations among localities seemed to relate to pollution of aquatic rather than terrestrial foods of storks. Toxic thresholds of mercury in this species are unknown, but the highest concentrations, observed in chicks from the Axios Delta (up to 4.1 μg.g‐1 in feathers) were well above levels having toxic effects in gamebirds. Mercury concentrations in chick feathers increased slightly with chick age and with brood size, but these trends were small by comparison with variations among localities.