American Oystercatcher

This large black and white shorebird uses its straight orange bill to stab and hammer bivalves, mollusks, and other invertebrates for food. Major threats to this species include habitat loss due to coastal development and human disturbance from recreational activities.

• Scientific name: Haematopus palliatus
• Species of Greatest Conservation Need (MA State Wildlife Action Plan)

Description

American oystercatcher (Haematopus palliatus)

A large (40-44 cm, 15.7-17.3 in long; 400-700 g, 14-25 oz), thick-set shorebird, the American oystercatcher has a black head and neck, a dark back, a white belly, large white patches on wings and tail, and a distinctive large, straight orange bill. A noisy bird, its vocalizations include a piercing wheep and a loud pic-pic-pic. 

Life cycle and behavior

There are both migratory and residential populations of American oystercatchers. Northern breeding populations, such as Massachusetts, are fully migratory, while populations in South Carolina, Georgia, and Texas are residential and make small movements outside of the breeding season. Migratory populations begin their northbound journeys starting last week of February into May. Massachusetts breeders arrive paired from last week in March to early April. American oystercatchers lay one clutch of three eggs per year. Both adults incubate eggs for around 27 days. Chicks are precocial at hatch and can run within hours. The family moves away from the nest within two days of hatch. Both adults share feeding responsibilities, and chicks depend on parents for at least 60 days. Families are maintained through southbound migration and onto the wintering grounds. Migration south begins in August and goes through mid-November.

Age at first breeding is likely three years old and maximum longevity records are a minimum of 17 years. 

American oystercatchers’ diets consist of bivalves, mollusks, crustaceans, worm, and other marine invertebrates. Feeding techniques include stabbing and hammering. When stabbing, American oystercatchers insert their bills into the open valve and severs the adductor chain. When hammering, American oystercatchers remove a mussel and brings it onto land. They then move the mussel to hammer it when the adductor chain is within the shell. 

Population status

The 2025 State of the Birds report reported the American oystercatcher population at over 14,000 individuals. This is a substantial increase from an estimated 10,000 individuals in 2009. The most recent MassWildlife American oystercatcher summary (2011) reported at least 418 adults and at least 202 pairs statewide. 

Distribution and abundance

American oystercatcher (Haematopus palliatus)

American oystercatchers are found along the Atlantic coast of the United States from mid-Maine to Florida, along the Gulf Coast south to the Yucatan Peninsula, and throughout the Caribbean in Puerto Rico, the Bahamas, the Virgin Islands, and Martinique. On the Pacific Coast, American oystercatchers are found from Baja California south to Chile. 

In Massachusetts, American oystercatchers are rare but increasing in abundance and expanding in distribution along the coast. Although American oystercatchers were first documented nesting in Massachusetts in 1969, their presence here is believed to be a re-occupation of former territory lost sometime after European colonization, rather than a new range extension. A statewide census in 2004 estimated 189 pairs at 58 sites in Massachusetts, with the largest numbers on Nantucket, Martha's Vineyard, Monomoy National Wildlife Refuge in Chatham, and the Boston Harbor Islands. Post-breeding concentrations of over 100 birds now occur annually in August on intertidal flats and beaches at the Monomoy Islands and South Beach in Chatham. 

Habitat

American oystercatchers use coastal habitats in both their breeding and non-breeding ranges. They nest above the high tide line on the upper portions of sandy or gravelly beaches, at the edges of salt marshes or dunes, or on low ridges within salt marshes. It feeds nearby on lower portions of beaches, on intertidal flats, and at edges of salt marshes. Historically, American oystercatchers were believed to nest on outer beaches, but are now nesting on dredge islands, gravel roofs, and occasionally on other anthropogenic infrastructure. This expansion to possibly novel habitats could be a response to range expansion or from habitat loss or human disturbance. 

Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.

Threats

American oystercatchers range-wide face threats from habitat loss due to coastal development, human disturbance, predation, and loss of food sources from habitat degradation (i.e. pollution and siltation). Disturbance from human recreation negatively impacts nest initiation and nest and chick survival, while predator control focused on mammalian predators increased American oystercatcher reproductive success. Sea level rise from climate change may also eliminate nesting and roosting habitats. 

Known threats in Massachusetts include mammalian and avian predation on eggs and chicks, and human-caused disturbance and mortality of eggs or chicks caused by human recreational activities, off-road vehicles, and dogs. Oil spills are also a potential threat. 

Conservation

Manomet Conservation Sciences, a science and collaborative non-profit based in Plymouth, Massachusetts, coordinates the American Oystercatcher Working Group. The working group develops, supports, and implements research and management range wide. These efforts include banding and resighting and developing breeding surveying protocols. MassWildlife’s Natural Heritage Endangered Species Program (NHESP) and other Massachusetts agencies and organizations census American oystercatchers and monitor annual reproductive success. 

Future management efforts suggested include identifying important habitat and food resources, protecting important sites, increasing public awareness and support, monitoring population status, and potentially building new habitat. Future research is needed on predation impacts, population trends, breeding biology, prey resources, migration, and possible threats from climate change.  

References

Melvin, S. M. Summary of 2011 Census of American oystercatchers in Massachusetts. Massachusetts Division of Fisheries and Wildlife, Natural Heritage and Endangered Species Program. Westborough, Massachusetts, 2012.

Nol, E. and R. C. Humphrey. American oystercatcher(Haematopus palliatus), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA, 2020. 

North American Bird Conservation Initiative. The State of the Birds, United States of America, 2025. 2025. StateoftheBirds.org

Petersen, W.R., and W.R. Meservey. Massachusetts Breeding Bird Atlas. Massachusetts Audubon Society and University of Massachusetts Press, Amherst, Massachusetts, 2003.

Veit, R., and W.R. Petersen. Birds of Massachusetts. Massachusetts Audubon Society, Lincoln, Massachusetts, 1993.

Date published:	April 22, 2025