A global assessment of the conservation status of the Black Oystercatcher Haematopus bachmani
83 – 96
26 August 14
David F. Tessler, James A. Johnson, Brad A. Andres, Sue Thomas, Richard B. Lanctot
Alaska Department of Fish and Game, Division of Wildlife Conservation, Wildlife Diversity Program, 333 Raspberry Road, Anchorage, Alaska 99518 USA
The Black Oystercatcher Haematopus bachmani, a monotypic species, is one of the less studied members of the genus. The global population of roughly 10,000 individuals is scattered unevenly along the North American Pacific Ocean coast from the Aleutian Islands to Baja California, with the vast majority (about 80%) in Alaska and British Columbia. Favouring rocky shorelines in areas of high tidal variation, they forage exclusively on intertidal macroinvertebrates (e.g. limpets and mussels). Because they are completely dependent on marine shorelines, the Black Oystercatcher is considered a sensitive indicator of the health of the rocky intertidal community. Breeding oystercatchers are highly territorial, and nesting densities are generally low; however, during the winter months they tend to aggregate in groups of tens to hundreds. Wintering distribution and seasonal movements are poorly characterized, but some breeding populations in the north are migratory while others are resident. Population estimates are based mainly on incidental observations made during seabird surveys and are insufficient to determine population trends. The Black Oystercatcher is listed as a species of ‘high concern’ throughout its range for multiple reasons: the small population size and restricted range; threats to its obligatory shoreline habitat; and susceptibility to a suite of ongoing anthropogenic and natural factors that may potentially limit long-term viability. Despite concern for this species, direct conservation efforts have been limited by a lack of information on factors such as the overall population status and trend, demographics, local and regional threats to survival and productivity, the locations and sizes of important wintering concentrations, and migratory connectivity between breeding and wintering sites. To address these concerns, the International Black Oystercatcher Working Group was formed to document existing information and gaps, and to determine and implement high priority action items. Members developed an Action Plan, whose contents are highlighted here. This plan was developed collaboratively as a single strategic planning resource for the conservation of this species throughout its range.