a1 Percy FitzPatrick Institute, University of Cape Town, Rondebosch 7701, South Africa, e-mail: [email protected]
The Spectacled Petrel Procellaria [aequinoctialis] conspicillata only breeds at Inaccessible Island, central South Atlantic Ocean. During the early 1980s the population was estimated to be at most 1,000 pairs, but hundreds of Spectacled Petrels have been killed annually in longline fisheries off the east coast of South America since at least 1987. Although the population is characterized by a unique plumage trait, it is still regarded as a subspecies of the White-chinned Petrel P. aequinoctialis. Analysis of calls and playback experiments show that the Spectacled Petrel is vocally distinct from White-chinned Petrels and should be regarded as a valid biological species. It is also slightly smaller and breeds earlier than the White-chinned Petrel. Given its small population size and known mortality on longlines, the Spectacled Petrel is Endangered in terms of IUCN criteria C1 and C2b. Longline fisheries operating off South America should institute measures to reduce seabird by-catch. A survey of the breeding population at Inaccessible Island is required to assess the rate at which the population is decreasing.