Initial deadline for comments: 31 January 2012.
White-headed Steamerduck Tachyeres leucocephalus is restricted to the coast of south-central Argentina where it inhabits rocky areas and sheltered bays, and breeds on offshore islands and peninsulas. It is currently listed as Near Threatened under criterion C2a(ii) on the basis that it has a population of 2,500-5,000 mature individuals, probably forming one subpopulation, which did not appear to be in decline and consequently was thought to be stable.
A recently published study estimated the total population at 3,428-3,673 adults (Agüero et al. 2011), suggesting that the current population estimate used by BirdLife is correct, but could be refined. However, Agüero et al. (2011) also provide evidence to suggest that the population is in decline. Oil exploration and extraction are taking place within 100 km of the centre of the species’s abundance, and sea currents mean that any spill in the main region of development would take oil towards the species’s range. Three major oil spills in the last 30 years that have affected steamerduck breeding areas are reported to have caused massive mortalities. The sediment and rocks within the range of T. leucocephalus are still contaminated with oil derivatives. Egg-collecting has been reported, but is probably limited in both its scope and intensity. The species may also be affected by the harvesting of macroalgae and guano, as well as other human activities such as recreation and small-scale coastal fishing. It may suffer predation during the breeding season from native species such as the Kelp Gull Larus dominicanus, whose population in Patagonia is increasing. Introduced species are also altering the ecology of near-shore ecosystems (Agüero et al. 2011). These threats imply that the population has experienced reductions over recent decades and is suffering from decreasing habitat quality.
It is suggested that the species could qualify for uplisting to Vulnerable under criterion C2a(ii), on the basis that its population of fewer than 10,000 mature individuals, which forms one subpopulation, is inferred to be experiencing a continuing decline owing to the decline of habitat quality, and probable decreases in survival and breeding success, as caused by human activities and other problematic species. Comments are invited on this suggested category change and further information would be welcomed.
Agüero, M. L., Borboroglu, P. G. and Esler, D. (2011) Distribution and abundance of Chubut Steamerducks: an endemic species to Central Patagonia, Argentina. Bird Conserv. Int.
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