Courtesy Kenn Kaufman
On the Atlantic coast, the American Oystercatcher generally breeds from Florida to Massachusetts. It is found year-round at various points around the Gulf Coast and Caribbean. In South America, it occurs as far south as Argentina on the Atlantic Coast, and Chile on the Pacific. In Mexico and Central America, it is found locally on both coasts, breeding as far north as Baja California.. Only about 12 percent of the species' global population occurs within the United States. Up to one third of the U.S. population is thought to winter in South Carolina alone.
A legend for the range map to the right can be found here
The strictly coastal American Oystercatcher prefers vast open areas of sandy dunes and tidal marshes. The birds often nest just above the high tide mark on sandy or rocky beaches with little vegetation, and feed in areas exposed by the receding tide, such as sandbars or shellfish beds. Secluded barrier or dredge spoil islands are often favored for nesting.
At low tide, oystercatchers can be found wading about in exposed beds of oysters, clams, or other mollusks, or at intertidal areas, probing the mud for food. When a shellfish is found, the oystercatcher deftly employs it long bill, inserting it knife-like between the valves of it prey, which is pried open and quickly consumed. The bill can also function more like a hammer, useful for pummeling sealed shellfish until they break apart. While bivalves such as oysters or clams are its main food source, the American Oystercatcher feeds opportunistically on prey such as shrimp, crabs, jellyfish, worms, insects, or even small fish.
In early spring, American Oystercatcher pairs select an elevated nest site beyond the high tide mark, generally with a full view of their surroundings. Together, the male and female construct a crude nest on the ground, where up to four eggs are laid. In areas of high nesting density, oystercatchers sometimes employ an atypical communal breeding strategy. One male and two females tend up to six eggs cooperatively, often in two nests. In either case, parents incubate the eggs for about four weeks. The semi-precocial chicks are led from the nest quickly. Unlike the young of most shorebirds, however, they cannot feed themselves right away, but rely primarily on their parents for food for up to eight weeks. Once independent, young American Oystercatchers flock together. While immature birds sometimes form pairs, they do not breed until at least their third year. Pairs may last for life.
Range wide, most American Oystercatcher populations are thought to be non-migratory. However, nearly all birds from New England to Maryland move south for the winter, generally departing by late September. The largest wintering Atlantic coast concentrations occur from Virginia through the Carolinas. The details of migration remain a mystery within Central and South America.