Seasonal changes in mercury accumulation in the black-eared kite, Milvus migrans lineatus

Seasonal changes of mercury accumulation in organs and tissues of the black-eared kite were investigated between the pre- and post-moult (April–November). The mercury concentration was high in the feathers, kidney and liver, and low in the skin and bone. About 70% of the mercury burden in the whole body was in the feathers. While the concentration of mercury decreased in most of the tissues during moulting (June–September), it remained constant in feathers throughout. This indicates that moulting is a major excretory pathway for mercury and the age-dependent accumulation of mercury is virtually absent in this species. The question of which kite feathers should be selected as indicators of mercury pollution in birds is discussed.