Distribution, abundance, habitat use and behaviour of three Procellaria petrels off South America
|Title||Distribution, abundance, habitat use and behaviour of three Procellaria petrels off South America|
|Publication Type||Journal Article|
|Year of Publication||2005|
|Authors||Spear, LB, Ainley, DG, Webb, SW|
|Type of Article||paper|
|Keywords||abundance, distribution, Parkinson's petrel, Procellaria, South America, Westland Petrel, White-chinned petrel|
We studied the distribution along the Pacific coast of South and Central America of three large petrels species that nest on New Zealand and subantarctic islands: white-chinned petrel (Procellaria aequinoctialis), Parkinson's petrel (P. parkinsoni) and Westland petrel (P. westlandica). During 15 cruises from 1980 to 1995, we conducted 1,020 hrs of surveys over 14,277 km2 of ocean from the shoreline to 1500 km off the coast from Chile north to Panama, and recorded 2114, 179, and 20 individuals, respectively, of the three species. White-chinned petrels occurred throughout the study area, but were most abundant off Chile, Parkinson's petrels were most abundant along the coasts of Ecuador and Peru, and Westland petrels off southern Chile. All three species preferred waters over the continental slope, although Parkinson's petrel was abundant also over the continental shelf during the austral winter. Densities of each species were positively related to oceanographic properties that are associated with upwelling features. Abundance estimates, analyzed using generalized additive models, peaked during the non-breeding season of each species. Estimates were 722,000 White-chinned petrels during austral autumn (95% confidence interval "CI" = 349,000 – 907,000); 38,000 Parkinson's petrels during austral autumn (95% CI = 28,000 – 50,000); and 3,500 Westland petrels during the austral spring (95% CI = 2,000 – 6,400). Scavenging appeared to be the primary feeding method of Procellaria, a habit that would make them susceptible to mortality as a result of their regular association with commercial fishing operations, particularly the recently developed long-line fishery on the continental slope of Chile.