Jukka Jantunen/Vireo

Priority Bird

Black Oystercatcher

Haematopus bachmani

Conservation status Still widespread along Pacific Coast, numerous in some areas. Vulnerable to effects of oil spills and other pollution in intertidal zone. Also very vulnerable to disturbance at nesting sites.
Family Oystercatchers
Habitat Rocky coasts, sea islets. Found at all seasons along rocky shorelines, especially on small offshore islands where predators are fewer; chooses areas with abundant shellfish and other marine life. In winter, also commonly found on mudflats close to rocky coastlines, but uses mudflats less in summer.
Where the Pacific Ocean breaks against rocky shorelines, pairs of these big black birds stalk about on the rocks and nearby flats. If disturbed, they take flight with loud, ringing whistles, easily heard above the sound of the waves. Their range stretches from Alaska to Baja, but Black Oystercatchers are scarce along the coast of southern California, where the shoreline is mostly sandy, not rocky.
Photo Gallery
Feeding Behavior

Forages mostly near low tide, resting at high tide. When feeding on mussel beds, typically removes the mussel from its shell and leaves the shell in place. The birds have two methods of opening the shells of bivalves. In one, finding a mussel with its shell slightly open, the oystercatcher quickly jabs its bill into the opening, cutting the muscles and then cleaning out the contents. In the other method, the bird simply hammers on the shell to break it open.


Eggs

2-3, sometimes 1. Pale buff to olive, spotted and scrawled with brown and black. Incubation is by both parents, 24-29 days. Young: Downy young remain near nest at first; parents take turns guarding the young and going to get food for them, walking back and forth to nearby intertidal zone. Older chicks follow their parents to feeding areas and are fed by them there. Young can fly at age 5 weeks or older; begin to catch some of their own food then, but are still fed by parents for some time thereafter.


Young

Downy young remain near nest at first; parents take turns guarding the young and going to get food for them, walking back and forth to nearby intertidal zone. Older chicks follow their parents to feeding areas and are fed by them there. Young can fly at age 5 weeks or older; begin to catch some of their own food then, but are still fed by parents for some time thereafter.

Diet

Mostly mussels, limpets, other shellfish. Diet varies with place and season, but feeds mostly on mussels where they are abundant; also limpets, whelks, urchins, crabs, marine worms, beetle larvae. Young birds, newly independent, may eat fewer mussels at first, perhaps lacking the skill to open them.


Nesting

May mate for life. Almost always nests on islands. Pairs typically defend a breeding territory that includes both an elevated area for nesting, well above high tide, and an adjacent feeding area with mussels beds or other food source. Nest site is on ground well above high-tide mark, on gravel, grassy area, or depression in rock. Nest (built by both sexes) is slight scrape, with sparse lining of pebbles, pieces of shell.

Text © Kenn Kaufman, adapted from
Lives of North American Birds

Illustration © David Allen Sibley.
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Migration

Mostly permanent resident. No regular migration, but wanderers away from breeding areas are most likely to be seen in spring and fall.

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Migration

Mostly permanent resident. No regular migration, but wanderers away from breeding areas are most likely to be seen in spring and fall.

Songs and Calls
A whistled wheeee-whee-whee-whee.
Coastal Stewardship: Atlantic & Pacific

Coastal Stewardship: Atlantic & Pacific

Protecting shorebirds in habitats especially vulnerable to development and climate threats

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