The Amazing American Oystercatcher -August 2016

One of our most colorful – and visible – shorebirds is the American Oystercatcher. It is a sturdy, sizable, black-and-white shorebird, but what really stands out is the hefty bright red “shucking knife” of a bill.

by: Virginia Andrews

photography by: Neil Foley

While many of the birds haunting our beaches are speckled variations on the theme of brown and white, differing mainly in relative size, Oystercatchers really catch an observer’s eye. From Smith’s Point to Coskata, and along the south shore, they can be seen as well in the shimmering heat and haze of mid-day as in the cool of early morning. With bright yellow, red-rimmed eyes they walk or run along sandy flats, probing for goodies hidden in the intertidal zone.

In spite of seeming so completely at home here, Oystercatchers are relatively new to Nantucket, at least in modern times. They may, however, simply be returning to their historic range after a long absence. By the early 19th century, hunting and egg-collecting had wiped out any traces of previous residence in New England. They were barely known to early Massachusetts ornithologists. Alexander Wilson was given one specimen collected from Boston Harbor some time before 1814. Two were shot in Marshfield in 1837, by no less a personage than Daniel Webster, the orator and Federalist statesman. Prior to 1955, there were only 11 Massachusetts records for the 20th century.

The first nest in our vicinity was discovered on Martha’s Vineyard in 1969. The following year a pair of pioneers arrived on Tuckernuck. They are now a common sight, delighting birders and beach-goers with their calls and antics.

Often stalking unwary bivalves on a falling tide, they use that impressively-colored beak to snip the adductor muscles of clams and mussels, slurping out the salty-sweet contents. They can simply bang open razor clams, breaking their fragile shells. Oystercatchers also gulp down many marine critters not generally considered appropriate for human consumption, such as moon-snails or ribbed mussels, and few people would begrudge them the nereid or polychaete worms that make up the bulk of their diet in Nantucket waters. And yes, living up to their name, sometimes Oystercatchers do also eat oysters. Despite their strong bills, the diet is not without risk. A determined bivalve has been known to snap closed on an intruding beak and hang on until the rising tide actually drowns the bird. On our south shore they feast on mole crabs, those thumb-sized crustaceans that thrive in the swash of ocean waves.

In courtship, two adults run together side by side, piping a single note. They do not stay together on migration, but will often reunite with the same mate on the breeding grounds, to which they return year after year. Their nest is a mere scrape in the sand, although they sometimes decorate it with pebbles or bits of shell. Sometimes made in the wrack of higher winter tides, the nest is usually well above the summer hightide line, but can be overwhelmed by unusually high spring tides or storm surges. In it the female lays up to three speckled eggs, almost indistinguishable from the beach itself.

For about a month, the parents take turns incubating the eggs, protecting them from overly hot sun or disastrously cold rain. Baby Oystercatchers start peeping in the shell a couple of days before pecking their way into the free air. Newly-hatched young remain in the nest for only a few hours while their downy fluff dries, before they toddle into the world. Almost invisible with their sand-like coloring, they are carefully tended by their parents, who feed and protect them. At about five weeks they begin to learn to fly. After the young have molted their down for real feathers, birds of the year can still be recognized by their grayish bills. Both parents care for them for about two months, although the family group may stay together through the summer. Then, starting around the end of September, they will take wing for southern shores, before starting the cycle anew.

But, as with many cycles of nature, we cannot take them for granted. Their population is small, and scattered from Maine to Florida. Only about 11,000 individuals constitute the entire North American population: about the number of Nantucket’s winter residents. And they are highly-vulnerable to storms, predators, pollution and human disturbance.

This makes them a Species of High Concern, in need of active conservation efforts. The American Oystercatcher Work-group, formed in 2001, is a multi-state partnership of organizations, dedicated to understanding the biology and needs of the species. Massachusetts Audubon and the Nantucket Conservation Foundation, which owns much of the land the birds use on the island, have been color-banding and monitoring “our” Oystercatchers for over 10 years.

Thanks to this work, we know that the greater Nantucket area, including Tuckernuck and Muskeget, has the distinction of hosting the highest concentration of American Oystercatchers in Massachusetts. With color bands identifying individuals, it was notable that a bird known affectionately – and technically – as “E2” made the 1,100-mile trip from Cedar Key, Fla., to Eel Point in four days. In other words, this clam-fueled aviator flew an average of 277 miles per day, under his own steam. Pairs often return to the same nest sites every year, but birds banded as chicks do not return until they are at least three years old. This means that protecting winter habitat is crucial to the species’ survival. Another bird, “AAR,” was banded in 2014, but was seen last year in Honduras. So, armed with better knowledge, we can hope to continue to see these delightful birds year after year. ///

Virginia Andrews writes the weekly “Island Bird Sightings” column for The Inquirer and Mirror and is a regular feature writer for Nantucket Today.

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