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New Jersey Endangered and Threatened Species Field Guide
Species Group: Bird
State: Special Concern (Breeding)
Standing nearly a foot and a half tall with a long, straight orange-red bill, the stocky black, brown, and white oystercatcher is not easily overlooked. Their loud calls and gregarious behavior makes them even harder to miss.
DISTRIBUTION AND HABITAT
The breeding range of the American oystercatcher includes the Atlantic coast of the U.S. from Massachusetts in the north to the coast of the Gulf of Mexico as well as the eastern coast of Mexico and the West Indies. They also breed along the Caribbean coast of South America and as far south along the Atlantic coast as Uruguay and Argentina.
The species also breeds along the Pacific coast from the Baja peninsula of Mexico in the north, along western Central America, and as far south as coastal Chile. They may be found year-round in locations in South America, Mexico, and the West Indies. New Jersey is the northern extent of their non-breeding range and many of the non-breeding U.S. oystercatchers winter in Florida, the West Indies, and the coast of the Gulf of Mexico.
American oystercatcher habitat includes rocky and sandy seacoasts and islands, river mouths and estuaries, and mudflats. Breeding habitat in New Jersey consists of coastal beaches and back-bay saltmarsh.
The American oystercatcher feeds on bivalve mollusks such as mussels, as well as echinoderms, crustaceans, and marine worms. It often feeds within the intertidal zone, pecking and probe the sand with its bill.
The breeding season in New Jersey is between early April and mid-August. The nest is a shallow hollow, either bare or lined with pieces of dead plants, small stones, or broken shells. Three eggs are usually laid and there is one brood each breeding season, but lost clutches will be replaced. Incubation is by both sexes and may last between 24 to 27 days. The young are precocial and are cared for by both parents. The young remain at the nest for 1 to 2 days after hatching. Afterward, they follow their parents and pick-up their own food, although their parents may still receive food from their parents. The young are then independent at between 34 to 37 days of age.
CURRENT STATUS, THREATS, AND CONSERVATION
Until recently, significant information gaps existed about oystercatchers in New Jersey. That is changing now that researchers have begun to focus more attention on them.
Once abundant along the entire Atlantic coast, oystercatchers were believed to be extirpated in the Northeast as a result of intensive market hunting and egg collecting in the 1800’s. With the passage of the Migratory Bird Treaty Act of 1918, the oystercatcher began to rebound. However, various factors including habitat loss from coastal development, human disturbance from recreational activity and elevated predator levels have kept the population low. Just how low is one of the questions biologists are now addressing. A range-wide aerial survey from New Jersey to Florida and the Gulf coast conducted in the winter of 2002-03 led to a population estimate of approximately 11,000 oystercatchers. In 2003, biologists in New Jersey began including oystercatchers in their annual breeding surveys of other beach nesting birds. Those surveys have found on average, about 60 breeding pairs on barrier beaches. However, because oystercatchers nest on back-bay marsh habitat as well, this only reflects a portion of the population.
In 2004, Tom Virzi, a PhD candidate at Rutgers University, began studying oystercatchers in hopes of better identifying the factors that impact reproductive success in the different nesting habitats. Virzi’s research quickly revealed that more oystercatchers were nesting in the back-bay areas, especially near inlets, than on the barrier beach strands. However, it wasn’t until 2007 that Virzi was able to survey most of the state’s suitable nesting habitat in the coastal zone. He found 332 breeding pairs, substantially more than expected. Because some areas were not included on the survey, experts estimate that approximately 400 pairs of oystercatchers nest in New Jersey.
New Jersey is also important for oystercatchers during the non-breeding season. As the northernmost state in the wintering range, some years it is host to nearly 1,000 oystercatchers, slightly less than 10% of the population. Unlike during the breeding season when they are highly territorial, oystercatchers gather in large roost flocks in the fall and winter. The flocks, which are generally in or near inlets, vary considerably in size. In New Jersey, flocks in Absecon and Hereford inlets are especially important as they number 200-350 birds each and often account for the majority of birds present during the non-breeding season. Although we know much more about oystercatchers now, many questions remain. We hope that continued monitoring and research will provide information about how long they live, chick survival rates, movement patterns, and population trends.
Oystercatchers are not currently listed as an endangered or threatened species in New Jersey, but experts are concerned enough to have changed their status to that of a species of “special concern.” Other birds – piping plovers, least terns, and black skimmers – that share the same nesting habitats and face the same threats have already been listed. If oystercatchers are to avoid that fate, a comprehensive conservation effort guided by the recent surge in research is critical.
Text written by Todd Pover in 2008. Edited by Michael J. Davenport in 2011.
Species: H. palliatus
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