An assessment of pollutants in eggs of Audouin's gull (Larus audouinii), a rare species of the Mediterranean sea.

Audouin's gull (Larus audouinii) is a very rare species endemic to the Mediterranean basin. A sub-population of an estimated 130 pairs is breeding in the Tuscan Archipelago, an area heavily polluted by mercury and chlorinated hydrocarbons. Here we present the data from 5 years spent monitoring the contaminant levels in the eggs of this species. Mercury, selenium, polychlorobiphenyls (PCBs) and DDE concentrations are two to five times higher than in similar species, such as the yellow-legged herring gull, nesting in the same area. The annual trends in these contaminant levels are discussed. In view of the endangered status of Audouin's gull, there is a need to observe closely the developing trend of contamination in this species.