- 15.7–17.3 in
- 14.1–24.7 oz
- L'Huîtrier-pie, L'Huîtrier d'Amérique (French)
- Ostrero (Spanish)
- Two races of American Oystercatcher breed in North America: the eastern race along the Atlantic coast, and a second race along the Pacific coast from northwestern Baja California southward. North of Baja California, the Black Oysercatcher takes over.
During the breeding season, American Oystercatchers can be found in coastal habitats including sand or shell beaches, dunes, saltmarsh, marsh islands, mudflats, and dredge spoil islands made of sand or gravel. During migration and winter, look for them feeding in mud or sand flats exposed by the tide, or on shellfish beds. These conspicuous birds tend to roost on beaches, dunes, or marsh islands near their foraging sites, and rarely venture far inland.
Feeds almost exclusively on shellfish and other marine invertebrates including mussels and clams of many varieties, limpets, oysters, sea urchins, starfish, crabs, and worms.
- Clutch Size
- 2–4 eggs
- Number of Broods
- 1 broods
- Egg Length
- 0.8–0.9 in
- Egg Width
- 0.6–0.6 in
- Incubation Period
- 24–28 days
- Nestling Period
- 1 days
- Egg Description
- Buffy gray speckled with dark brown.
- Condition at Hatching
- Active and coordinated, covered in tan down; leaves the nest within one day of hatching.
Adults use their feet to scrape out a shallow depression from the sand. They make five or more of these, then choose one and line it with shells, pebbles, or bits of tide wrack. The depression is about 8 inches across and 2.5 inches deep.
American Oystercatchers commonly nest on high, sandy sites such as dunes; low, flat, sandy areas with good cover; dredge spoil; or marsh islands. Suitable nest sites can be in short supply sometimes forcing oystercatchers to nest very close to the high-tide line; spring tides during full or new moons can flood and ruin many such nests.
American Oystercatchers use their long, bladelike, orange bills to catch shellfish unawares, seizing them before they can close up. frequently walk or run rather than flying. They walk across shellfish beds and when they encounter one that is partially open, they jab their bill into the shell and sever the strong muscle that clamps the shells shut. The technique is not without its risks though—oystercatchers do sometimes drown after a tightly rooted mussel clamps down on their bills and holds the bird in place until the tide comes in. The birds also feed by carrying loose shellfish out of the water and hammering at the shell, or by probing for buried soft-shell or razor clams the way some other shorebirds do. Courting birds tend to walk together and make a single piping note. This progresses to leaning over, extending and lowering the neck, and running side by side while calling. Eventually the pair may burst into flight and fly in tight formation around their territory, sometimes joined by birds from adjoining territories.
American Oystercatchers are a species of special concern in several coastal states and are listed as a "yellow" species (indicating a national conservation concern) by Audubon. Several thousand American Oystercatchers live in the United States with most of them breeding in the mid-Atlantic states. Though they also occur along the Gulf of Mexico, the lower tidal ranges there expose less foraging area and this may keep oystercatcher numbers lower in that region. Oystercatchers are shy birds that are sensitive to human disturbance and to loss, degradation, or development of their beach habitat. They are also vulnerable to attack by gulls and typically do not nest alongside gulls—further restricting the nesting habitat available to them. Storms and high tides can swamp eggs or nestlings when the birds are forced to nest close to the high water mark. One benefit of human activity has been the appearance of sand islands made from dredging spoils. These are isolated from mammalian predators and often fairly high above the water, creating safe nesting habitat for this species.
- Nol, E. and R. C. Humphrey. 1994. American Oystercatcher (Haematopus palliatus). In The Birds of North America, No. 82 (A. Poole and F.Gill,Eds.). Philadelphia:The Academy of Natural Sciences; Washington, D. C.: The American Ornithologists' Union.