Species Fact Sheet Black oystercatcher Haematopus bachmani
STATUS: SPECIES OF CONCERN
Black oystercatcher potentially occurs in these Oregon counties: Clatsop, Coos, Curry, Douglas, Lane, Lincoln, Tillamook (Map may reflect historical as well as recent sightings)
The black oystercatcher is a keystone species along the North Pacific
shoreline and is believed to be a particularly sensitive indicator of
the overall health of the rocky intertidal community. Annual surveys
have been conducted along the Oregon Coast since 2005.
The black oystercatcher is a large, long-lived shorebird about 38 centimeters
(15 inches) in length with a long, thick, reddish-orange bill, a yellow
eye encircled by an orange ring, and pink legs, all of which are strikingly
set off by entirely black plumage. Juveniles have somewhat browner
plumage and a dark tip on the bill. Oystercatchers are monogamous,
returning to the same nesting territories to pair with the same
mate each year.
Black oystercatchers occur along the North American Pacific coast
from the Aleutian Islands to Baja California, and are most
abundant in the northern portions of their range, from Alaska to
southern British Columbia. Breeding oystercatchers are highly territorial
and nesting densities are low; however, the birds tend to gather
in groups of tens to hundreds during the winter months.
The world population of black oystercatchers is estimated at 10,000. In
Oregon, the estimated population, based on seabird survey information
from the late 1980s is 350. Approximately 250 individuals have been
found annually during land-based surveys along the Oregon Coast between
2005 and 2007. This number does not include black oystercatchers
on offshore rocks and islands too distant to survey from the mainland. The
black oystercatcher is a U.S. Fish and Wildlife Service “Species
of Concern” because of its small population size, restricted range,
and threats to habitat from human and natural factors that may potentially
limit its long-term viability.
Habitat and Diet
Oystercatchers inhabit marine shorelines, favoring rocky shorelines. They
make their nests above the high tide line on offshore rocks, rocky shores,
and sand/gravel beaches. The typical nest bowl is a small depression in
the sediment containing rock flakes, pebbles, and shell fragments. Foraging
habitat is primarily low-sloping gravel or rock beaches where prey is
abundant. Oystercatchers feed on a variety of intertidal invertebrates
including mussels, limpets, chitons, crabs, barnacles and other small
creatures. Contrary to what their name implies, they do not feed
Reasons for Decline
Black oystercatchers are highly vulnerable to natural and human disturbances.
Major threats include predation of eggs and young by native and non-native
predators; coastal development; human disturbance (e.g., induced nest
abandonment, nest trampling); vessel wakes, especially when they coincide
with high tides; shoreline contamination such as oil spills (resulting
in both direct mortality and indirect effects such as reduction in food
availability or quality); and global climate change, with its resultant
effects on feeding and/or nesting resources. Information is lacking
on contaminant and pollutant levels locally, and how these might affect
fitness, especially in or near highly developed areas within the species’ range.
Currently, conservation efforts for the black oystercatcher are limited
by a lack of baseline information for many areas on the following: the
locations and sizes of important breeding populations; local and overall
population status and trends; hatching success, fledging success and adult
survival; regional threats to survival and productivity; the locations
of important wintering concentration areas and the numbers of birds in
those areas; movements between breeding and wintering sites; and population
In Oregon, management plans to protect the black oystercatcher are being developed
and will likely begin with signage at key nesting sites to prevent disturbance
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.). Academy of Natural Sciences. Philadelphia, and American
Ornithological Union. Washington D.C.
Brown, S., C. Hickey, and B. Harrington [Eds.]. 2000. United States Shorebird
Conservation Plan. Manomet Center for Conservation Sciences. Manomet,
Hodder, J. Black Oystercatcher pp. 209-210 in Birds of
Oregon: A General Reference. D.B. Marshall, M.G. Hunter, and
A.L. Contreras, Eds. Oregon State University Press, Corvallis, OR.
Pitman, R. L., J. Hodder, M. R. Graybill, and D. H. Varoujean. 1985. Catalog
of Oregon Seabird Colonies. Unpublished Report. U.S. Fish and Wildlife Service.
Purdy, M.A. and E. H. Miller. 1988. Time budge and parental behavior of breeding
America Black Oystercatcher (Haematopus bachmani) in British Columbia.
Canadian Journal of Zoology 66:1742-1751.
Tessler, D.F., J.A. Johnson, B.A. Andres, S. Thomas, and R.B. Lanctot. 2007.
Black Oystercatcher (Haematopus bachmani) Conservation Action Plan.
International Black Oystercatcher Working Group, Alaska Department of Fish and
Game, Anchorage, Alaska, U.S. Fish and Wildlife Service, Anchorage, Alaska, and
Manomet Center for Conservation Sciences, Manomet, MA. 115 pp.
US Fish and Wildlife Service. Unpublished data from the 1988 Oregon
seabird colony survey. U.S. Fish and Wildlife Service, Oregon Coastal
Refuges Headquarters, Newport, OR.