Black Oystercatcher, Haematopus bachmani

Andres, Brad

The black oystercatcher is a large, dark shorebird that inhabits rocky shorelines along the Pacific coast of North America. Its long orange-red bill, bright yellow eyes, and large pink feet give the oystercatcher a comical appearance. Oystercatchers breed from the western Aleutian Islands in Alaska south to central Baja, California. Within Alaska, they have ranged northward to the Pribilof Islands in winter and to Round Island, Bristol Bay, to nest in the summer. Ranges of the black oystercatcher and the brown-and-white American oystercatcher overlap in Baja California. Black oystercatchers are dependent on marine shorelines for their life requirements and are most abundant along low-sloping gravel or rocky shorelines. Because this habitat is limited or occurs in patches, they are distributed unevenly and are uncommon throughout their range. The entire world population is estimated at about 11,000 individuals. More than 50% of that population occurs in Alaska and about 1,500-2,000 individuals reside in Southcoastal Alaska. Direct and indirect effects of human disturbance to shoreline habitats probably have reduced the black oystercatcher population from historical levels. Oystercatchers are uncommon to fairly common inhabitants of Prince William Sound (PWS). Pre-spill population levels of oystercatchers in PWS were estimated at 500-900 individuals. These estimates are imprecise and no information is available on pre-spill population trends. Historical population size in PWS is thought to be similar to the present-day level. Although oystercatchers are generally resident across their range, most individuals join post-breeding flocks that remain near their nesting areas throughout the winter. Individuals in northern populations might undertake longer migrations than those in southern populations. Only about 25% of the oystercatchers breeding in PWS remain there in the winter, but locations of oystercatchers that leave PWS in winter is unknown. Flocks, consisting of non-breeders and failed breeders, increase throughout July and August, depart PWS in September, and return the following March and April.

Black Oystercatcher, Haematopus bachmani

Series