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Status: Population size: 8,850 Photo by Bruce Reid.

Black Oystercatcher
(Haematopus bachmani)

This species was on the 2002 WatchList, but is not on the 2007 WatchList. Please refer to http://web1.audubon.org/science/species/watchlist/techReport.php for information on the 2007 WatchList.

Black Oystercatcher is a permanent resident of the rocky Pacific Coast of North America, where it sometimes associates with Surfbird, Black Turnstone, and Rock Sandpiper. With a relatively small population size, it is especially at risk from the effects of oil spills and other coastal pollution. This species is also extremely sensitive to the presence of humans on potential nesting islands.

Identification
Black Oystercatcher is one of the most distinctive birds in all of North America: a large, all-black shorebird, with the heavy, bright-red bill typical of oystercatchers.

Distribution and Population Trends
Black Oystercatcher is found along almost the entire Pacific Coast of North America, stretching from southern Alaska all the way to Baja California. The species is for the most part sedentary, although some individuals exhibit post-breeding wandering. During the wintertime, Black Oystercatchers can be seen in an extraordinarily large concentration at Audubon's Crescent Harbor Marshes Important Bird Area (IBA), in Washington. Significant breeding populations of this oystercatcher can be found at two Canadian IBAs in British Columbia: Kyuquot Channel Islets IBA (125 pairs) and Moore and Byers Islands and Banks IBA (79 pairs).

No population trends are currently available for Black Oystercatcher due to a lack of large-scale comprehensive study of this species.

Ecology
Black Oystercatcher is almost always found along the rocky shoreline of the Pacific Coast, although in winter, it can also occur on nearby mudflats. This oystercatcher feeds mostly on mussels, but its diet also includes limpets, whelks, and other marine organisms. It forages primarily at low tide and then rests at high tide. Black Oystercatcher nests almost exclusively on islands, where a pair builds a nest above the high tide mark and then defends an adjacent feeding area. The nest is a scrape placed in gravel, a grassy area, or a depression in rock. Both sexes incubate a typical clutch of 2-3 eggs, which hatch after about four weeks. Downy chicks remain near their nest at first, with one parent guarding the young while the other forages nearby. Eventually, young birds are led by their parents to feeding areas, but they continue to be fed by the adults until after they are capable of flight at five weeks of age.

Threats
The U.S. Shorebird Conservation Plan lists Black Oystercatcher as a "Species of High Concern," based on relative abundance, threats on breeding grounds, and non-breeding distribution. The species' small population size places it at risk to large-scale disturbances, such as oil spills. The 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, had a major impact on breeding oystercatchers in that area: 20% of the population in the spill area was directly killed by the spill; breeding activity was disrupted in 39% of the oystercatcher pairs attempting to nest on heavily-oiled shorelines; and the survival of chicks was reduced. Human activities also pose a threat to this species on a smaller scale. The presence of humans on potential nesting islands will often inhibit nesting attempts by Black Oystercatcher. In addition, the introduction of predators such as foxes and rats on nesting islands can create a major threat to breeding Black Oystercatchers.

Conservation
Most conservation management for Black Oystercatcher is on a local level, addressing concerns such as introduced predators on nesting islands. Since this species is dependent on marine invertebrates and other marine food items, the protection of water quality in feeding areas is also an important conservation issue. Because this species has such a limited population, areas that host high numbers of breeding or wintering Black Oystercatcher should be identified and conserved, in order to protect birds from oil spills and other major disturbances.

What Can You Do?
Audubon's Important Bird Area program is a vital tool for the conservation of Black Oystercatcher as well as other species. To learn more about the Important Bird Areas program and how you can help, visit: http://www.audubon.org/bird/iba/.

Information on where Black Oystercatchers occur and in what numbers is vital to conserving the species. Help in monitoring this and other species by reporting your sightings to eBird. A project of Audubon and the Cornell Lab of Ornithology, eBird is the world's first comprehensive on-line bird monitoring program: http://www.audubon.org/bird/ebird/index.html.

Volunteers are crucial to the success of programs that monitor the long-term status of wintering populations of Black Oystercatcher and other bird species. Audubon's Christmas Bird Count (CBC) is one of the longest-running citizen-science monitoring programs in the world and has helped to follow changes in the numbers and distribution of Black Oystercatcher. To learn more about the CBC and how you can participate, visit: http://www.audubon.org/bird/cbc.

References
Andres, B. A., and G. A. Falxa. 1995. Black Oystercatcher (Haematopus bachmani). In The Birds of North America, No. 155 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Hayman, P., J. Marchant, and T. Prater. 1986. Shorebirds, An Identification Guide. Houghton Mifflin
Company, Boston.

Kaufman, Kenn. 1996. Lives of North American Birds. Houghton Mifflin Company, New York.