Harvesting young birds or 'muttonbirding' currently accounts for the take of around a quarter of a million birds annually2,3,but is unlikely to account for the scale of the decline. Populations are no longer ravaged by pelagic drift-nets which formerly drowned up to 350,000 birds annually11. Longline fisheries are responsible for large numbers of deaths of this and many other seabird species. Some authorities postulate that the decline may be associated with climate change9. Rats (Rattus rattus and R. Norvegicus) have been shown to predate on eggs and chicks, altohough the extent of the impact is unknown13.