Seabirds are convenient indicators of contamination of the marine environment because feathers can be sampled non-destructively, and a great deal is known about their ecology. Flesh-footed Shearwaters (Puffinus carneipes) are of conservation concern in Australia and New Zealand, partly because ingestion of marine debris may be reducing breeding success at their largest colony. Because marine plastics accumulate contaminants in the ocean environment, an assessment of metal and metalloid contaminants was initiated. We sampled feathers from Kauwahaia (n = 18) and Lady Alice Island, New Zealand (n = 30), Lord Howe Island (n = 24) and Western Australia (n = 33) during the 2008 austral summer, making this the most complete assessment of metal and metalloid contamination of any shearwater. We found colony differences in all elements except lead and thallium. Samples from Western Australia had higher silver, aluminium, cadmium, and copper concentrations, while shearwaters from Lord Howe Island (eastern Australia) had elevated concentrations of mercury (mean ± S.D., 11221 ± 5612 ppb). We conclude that mercury, and potentially arsenic and cadmiumrepresent toxicological concerns for this declining species.