Metals in feathers of bonin petrel, Christmas shearwater, wedge-tailed shearwater, and red-tailed tropicbird in the Hawaian Islands, northern Pacific

Levels of environmental pollutants are usually higher in mainland and coast al areas than in offshore or oceanic islands due to higher inputs from agri cultural and industrial sources. Levels of heavy metals are usually higher in adult than in young birds, because they have had longer to accumulate me tals in their tissues, and/or because they may eat larger, more contaminate d, prey. We examined the levels of arsenic, cadmium, chromium, lead, mangan ese, mercury, and selenium in the adults and young of Bonin petrel (Pterodr oma hypoleuca), Christmas shearwater (Puffinus nativitatis) and red-tailed tropicbird (Phaethon rubricauda) on Midway Atoll, and adult wedge-tailed sh earwater (Puffinus pacificus) on Midway Atoll and on Manana Island (off Oah u) in the northern Pacific. All birds were analyzed individually except for Christmas Shearwater chicks where samples were pooled to obtain sufficient quantities for analysis. Significant (p < 0.05) age-related differences we re found for mercury, selenium, manganese and chromium in Bonin petrels, fo r selenium and mercury in Christmas shearwaters, and for chromium and mercu ry in Red-tailed Tropicbirds. Lead approached significance for all three sp ecies. Adults had higher levels than young except for chromium and manganes e in the petrels and arsenic in all three species. There were significant i nterspecific differences in concentrations of all metals except arsenic for the adults nesting on Midway. Christmas shearwaters had the highest levels of all metals except mercury and chromium. Bonin petrels, the smallest spe cies examined, had mercury levels that were over three times higher than an y of the adults of the other three species. For wedge-tailed shearwaters, l evels of chromium and lead were significantly higher, and manganese and sel enium were lower on Midway than Manana. Knowledge of the foraging ranges an d habits of these far-ranging seabirds is inadequately known, but does not currently explain the observed differences among species. We could not find a consistent pattern of differences between the burrow nesting species (Bo nin petrel, Wedge-tailed shearwater) and the surface nesting tropicbirds. T here was no consistent pairwise correlation between any metals across all s pecies.