The American Oystercatcher (Haematopus palliatus) is a strictly coastal species associated with rocky and sandy seacoasts, tidal mudflats, and salt marshes. It breeds locally along the Atlantic coast from Massachusetts south to Florida and along the Gulf coast south to the Yucatan Peninsula; in the Bahamas, Greater Antilles, and Lesser Antilles; along the Pacific coast from central Baja California south to central Chile; and along the Caribbean-Atlantic coast south to south-central Argentina. The primary wintering range extends from Maryland south to southeastern Mexico on the Atlantic-Gulf coast; along the North American Pacific coast from central Baja California south to Honduras, as well as in Costa Rica; and generally in the breeding range in the West Indies and along both coasts of South America. (Kaufman 1996; AOU 1998).

American Oystercatcher numbers declined seriously in the 19th century, but recovered substantially during the 20th century. Despite disturbance in beach habitats, in many areas breeding oystercatchers are doing well, often nesting on dredge spoil islands. Davis et al. (2001) estimated the number of American Oystercatchers breeding along the entire Atlantic coast and the Gulf coast of Florida at 1,624 pairs. North of Virginia, they reported stable or slowly increasing numbers, with the range expanding as far north as Cape Sable Island in Nova Scotia. However, there is good reason for concern about overall population trajectories. From Virginia south, Davis et al. reported a decline in breeding numbers, with the number of oystercatchers breeding on barrier islands in Virginia decreasing by more than 50% in the last 2 decades of the 20th century. Given their relatively small numbers and inherently low productivity, the authors suggest that American Oystercatchers are at risk in rapidly changing coastal ecosystems. (Davis et al. 2001)

The American Oystercatcher breeds locally along the Atlantic coast from Massachusetts south to Florida and along the Gulf coast south to the Yucatan Peninsula; in the Bahamas, Greater Antilles, and Lesser Antilles; along the Pacific coast from central Baja California south to central Chile; and along the Caribbean-Atlantic coast south to south-central Argentina. The primary wintering range extends from Maryland south to southeastern Mexico on the Atlantic-Gulf coast; along the North American Pacific coast from central Baja California south to Honduras, as well as in Costa Rica; and generally in the breeding range in the West Indies and along both coasts of South America. (AOU 1998)

In the 1800s American Oystercatchers bred along the entire Atlantic coast, perhaps as far north as Labrador and certainly as far north as Maine. By the early 1900s, oystercatchers had disappeared from the northern part of their range and Virginia was the most northern nesting location known on the Atlantic coast. Even south of Virginia, where they once were considered abundant, oystercatcher nesting in the early 1900s was rare. This decline was generally attributed to gunners who were hunting spring long distance migrating shorebirds on coastal beaches. Oystercatchers were an easy target and their nests were destroyed. After the passage of the Migratory Treaty Act in 1918, breeding abundance and distribution of oystercatchers on the Atlantic coast increased and they now breed as far north as Nova Scotia, Canada (Sanders et al 2008 and references therein).

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDS: locally along Atlantic and Gulf coasts from Massachusetts south to Yucatan Peninsula and West Indies, along Pacific coast from central Baja California and Gulf of California to Guerrero, along coast of Costa Rica, and from Bay of Panama south to central Chile, and along Caribbean-Atlantic coast of South America to south-central Argentina. NORTHERN WINTER: north to North Carolina and Baja California, south to southeastern Mexico, Guatemala, and Honduras, generally in breeding range in West Indies and coastal South America (AOU 1983).

Length: 47 cm

Weight: 632 grams

Oystercatchers differ from other shorebirds in having a large, straight, laterally compressed, orange bill with a rounded tip and both mandibles the same length. Differs from American black oystercatcher by having extensive white areas in plumage (vs. all-black plumage).

• Terrestrial
• Marine

Comments: Rocky and sandy seacoasts and islands (AOU 1983); river mouths and estuaries, especially where rocks exposed at low tide; mudflats, salt ponds (Stiles and Skutch 1989).

Nests on the ground in open sites often on high parts of sandy beaches, also among rocks, on islands, on shingle beds, occasionally in saltmarsh (Harrison 1979, Harrison 1978, Shields and Parnell 1990). In marsh habitats, nested on sand in North Carolina, on sand, wrack, or grass in New York and New Jersey (Lauro and Burger 1989).

The American Oystercatcher is found on rocky and sandy seacoasts and islands and on tidal mudflats (AOU 1998).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Migratory only at northern and southern extremes of range (Bent 1929). Northern populations migrate as far south as northern South America; migrant in Costa Rica August-early October and April-May (Stiles and Skutch 1989).

Comments: Eats mainly bivalves, echinoderms, crustaceans, and marine worms (Terres 1980). Often forages in intertidal zone; pecks and probes mud or sand, often through shallow water (Stiles and Skutch 1989).

Khatchikian et al. (2002) studied kleptoparasitism (food stealing) by Brown-hooded Gulls (Larus maculipennis) and Gray-hooded Gulls (Larus cirrocephalus) stealing from American Oystercatchers in a coastal lagoon in Argentina. Most kleptoparasitic attacks (96%) occurred within the first three seconds of ingestion of clams by an oystercatcher, after they had opened the valves. Gulls lacked the skills required to open clams; in two cases it was observed that gulls were unable to open stolen clams that had not been opened by oystercatchers. Gulls were never observed swallowing whole clams. The overall occurrence rate was 1.2 ± 1.3 attempts per 5 minutes; 42% of attempts were successful. All kleptoparasitic attempts were made on oystercatchers feeding on Stout Razor Clams (Tagellus plebeius). Gulls stole food from oystercatchers using two different kleptoparasitic tactics; running (used in 40% of cases) and flying (used in 60% of cases). In the first, gulls approached their hosts by running from a nearby position, while in the latter, the gulls flew toward the oystercatchers.

In a study in Argentina, Daleo et al. (2005) found that carcasses of the intertidal grapsid crab Cyrtograpsus angulatus that had been abandoned by American Oystercatchers stabbing female crabs to obtain their eggs (and, occasionally, male crabs to consume their viscera) provided a significant source of food for the intertidal scavenging snail Buccinanops globulosum.

American Oystercatchers are known to feed on a variety of intertidal benthic prey such as oysters, limpets, mussels, polychaetes, crabs, jellyfishes, sea urchins, and ascidian tunicates in the northern and southern hemispheres (Kaufman 1996; Pacheco and Castilla 2001 and references therein).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

10,000 - 100,000 individuals

Comments: North American populations are estimated to be about 8850; populations in South America are considerably larger, at least on the order of 50,000 (Morrison et al. 2001).

Often in pairs. Nesting density was 0.66-1.00 pairs/ha in Virginia, 4.86-13.05 pairs/ha in New York (Lauro et al. 1992).

Clutch size is 2-4 (usually 2-3). Incubation lasts 27 days, by both sexes. Young are tended by both parents, leave nest in 1-2 days, probably first fly at about 5 weeks. Initially, young depend almost entirely on parents for food.

In Virginia, reproductive success was highly variable; large proportion of pairs failed to fledge young; losses due mainly to high tides and predation (Nol 1989).

Typically monogamous; care of both parents may be required for successful reproduction; communal breeding has been observed (Lauro et al. 1992).

Although American Oystercatchers are typically monogamous, with strong pair bonds that often persist for many years, in a dense breeding colony in New York Lauro et al. (1992) found a relatively high rate of communal nesting (one male with two females). This phenomenon appeared to be a direct consequence of the high nesting densities in this colony, resulting in a shortage of high quality territories.

The typical clutch size is 1 to 4 eggs (more for nests with two females). Incubation, which is carried out by both sexes, is 24 to 28 days. Downy young leave the nest shortly after hatching, but both parents continue to help feed young for at least two months. First flight is at about five weeks. (Kaufman 1996)

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

Reasons: Secure due primarily to extensive range; recent range expansion has occurred in some areas.

Davis et al. (2001) estimated the number of American Oystercatchers breeding along the entire Atlantic coast and the Gulf coast of Florida at 1,624 pairs. North of Virginia, they reported stable or slowly increasing numbers, with the range expanding as far north as Cape Sable Island in Nova Scotia. From Virginia south, they reported a recent decline in breeding numbers, with the number of oystercatchers breeding on barrier islands in Virginia decreasing by more than 50% in the last 2 decades of the 20th century. Given their relatively small numbers and inherently low productivity, the authors suggest that American Oystercatchers are at risk in rapidly changing coastal ecosystems. (Davis et al. 2001)

Brown et al. (2005) undertook an aerial survey to assess population size and winter distribution of the eastern subspecies of American Oystercatcher, whose winter range extends from New Jersey to Texas. Using a combination of ground and aerial counts, they estimated the population of eastern American Oystercatchers to be around 11,000.

According to Wilke et al. (2007), Chesapeake Bay, coastal bays, and barrier island shorelines of Maryland and Virginia harbor around 700 breeding pairs of American Oystercatchers. More than 80% of these are found on the east coast of the Delmarva Peninsula while fewer than 20% occur along the shorelines of the Chesapeake Bay. According to Wilke et al., the number of breeding pairs in Maryland appears to have been stable or to have increased slightly during the past 20 years.The authors report that the overall trend of the breeding population in Virginia is less clear, but that recent evidence suggests that numbers on the barrier islands are increasing after more than two decades of a declining trend. The coastal bays and barrier islands typically support between 1,500 and 2,000 wintering birds, with most occurring on the east coast of the Virginia portion of the Delmarva Peninsula. (Wilke et al 2005).

In South Carolina, Sanders et al. (2008) counted around 1,100 American Oystercatchers each year during a 3 year survey, roughly a third of them nonbreeders.

American Oystercatcher numbers declined seriously in the 19th century, but recovered substantially during the 20th century. Despite disturbance in beach habitats, in many areas breeding oystercatchers are doing well, often nesting on dredge spoil islands. (Kaufman 1996)

A study of breeding American Oystercatchers in coastal North Carolina found that all-terrain vehicle traffic was associated with increased rates of trips to and from the nest and reduced time incubating (McGowan and Simons 2006).

According to Wilke et al. (2007), throughout the Chesapeake region oystercatchers are facing threats common to all coastal waterbird and shorebird species, such as predation and overwash events. The threat of habitat loss to development, however, is not as alarming as in other areas of the species’ breeding range due to a significant amount of habitat being either currently protected or unfit for development and recreation purposes. Habitat loss attributed to sea level rise, barrier island dynamics, and the indirect effects of development, such as pollution and contaminants, may play more important roles in the stability of breeding and wintering habitat for the American Oystercatcher in Maryland and Virginia. (Wilke et al. 2007)

Comments: Considered conspecific with H. bachmani and H. ostralegus by some authors (AOU 1983). The three taxa constitute a superspecies (AOU 1998). Jehl (1984) concluded that palliatus and bachmani are distinct species; see DeBenedictis (1990) for contrary view.