Evaluation of claws as an alternative route of mercury elimination from the herring gull (Larus argentatus)

Mercury enters the body of seabirds in its most toxic organic form, i.e. methylmercury, mainly via the alimentary tract. Inside the body, mercury is transformed into less toxic forms and accumulates in the internal organs. The process of mercury removal from the body, most effective during the formation of new feathers and claws, is beneficial for the bird. The presented research was undertaken on account of the high affinity of mercury to keratin – a protein that forms feathers and claws – to compare the concentration levels (Hg_TOT) in these structures and to assess their contribution to the purification of the body of herring gulls (Larus argentatus) Bird feathers are the only epidermal structure that is extensively described in the literature, whereas the claws have so far been poorly researched.

The study has shown that mercury in claws is built in as effectively as in feathers, and the obtained concentrations were within a wide range of 127.2–5341.5 ng Hg_TOT g^–1 of dry weight. In addition, the concentrations of total mercury accumulated in the claws were a better reflection of Hg levels in internal organs compared to feathers.