American Oystercatcher

Haematopus palliatus
American Oystercatcher by Kirk Rogers

A large, boldly patterned bird, the American Oystercatcher is conspicuous along ocean shores and salt marshes. True to its name, it is specialized in feeding on bivalves (oysters, clams, and mussels) and uses its brightly colored bill to get at them.

Description and Diet
Large, pied shorebird (40–44 cm long; 400–700 g), dark above on head and mantle, white on breast and flanks. Long, straight, bright red to orange bill. Long, pale pink legs, lacks hallux. Bright yellow iris, sometimes with dark flecks. Shows narrow, white wing stripe in flight. Long reddish bill laterally compressed. Yellow eyes with red eye ring and black head and neck, contrasting with brown mantle, distinguishes this from other species. Males and females visually indistinguishable. Juveniles have varying degrees of dusty orange to gray on bill and mottled brown feathers on back until fully mature. Otherwise similar to adult. 

Oystercatchers feed almost exclusively on shellfish and other marine invertebrates including mussels and clams of many varieties, limpets, oysters, sea urchins, starfish, crabs, and worms.

Habitat
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.

Behavior
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.

Conservation
The North American population of American Oystercatchers are on the 2014 State of the Birds Watch List, which lists species most in danger of extinction without significant conservation action. This species is 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.

Facts About American Oystercatcher

Diet
Specialized in feeding on bivalves such as oysters, clams, and mussels
Habitat
Coastal marshes and sand beaches
Did You Know?
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.