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August 2021

Vol. 49, No. 4

Front Cover: August 2021

Willet, by John Sill

John Sill is a freelance wildlife artist living in the mountains of North Carolina. He was the illustrator for the Bird Identification Calendar for Mass Audubon for many years. His work has appeared in Birds In Art at the Leigh-Yawkey Woodson Art Museum, Wausau, Wisconsin, and in Art of the Animal Kingdom at the Bennington Center for the Arts in Vermont. He continues to illustrate the “About” and “About Habitats” series of natural history books for children written by his wife Cathryn.

Willet

The Willet (Tringa semipalmata) is a drab shorebird until it opens its wings to show the magnificent black-and-white wing pattern above and below that instantly transforms it into a spectacular shorebird. The black-and-white wing pattern is distinctive, with a bold white stripe extending through the base of the black primary and secondary feathers. There is also white on much of the leading edge of the wing. The Willet is a large, brownish gray shorebird that, in breeding plumage, has barred and streaked patterns of black and brown on all but its white belly. In winter plumage, it is mostly plain brownish gray. It has a heavy, straight, long, mostly black bill, gray legs, and a white rump.

There are two subspecies, T. s. semipalmata, the “Eastern” Willet, and T. s. inornata, the “Western” Willet. The two subspecies differ in size, plumage, vocalizations, and location of both breeding and wintering areas. They differ enough that some researchers consider them separate species. Western Willets breed in the western interior of North America, from northeastern California, Nevada, Utah, and Oregon through Idaho, Montana, the Dakotas, Nebraska, Wyoming, and Colorado, and north into Alberta, Manitoba, and Saskatchewan. Also, some are year-round residents in the Bahamas south to Venezuela, where they breed locally. Western Willets winter along the West Coast from Washington State to Mexico, and along the west coast of Mexico and Central America south to Chile. On the East Coast, Western Willets winter along the Atlantic coast from the Carolinas southward, along the Gulf coast, through eastern coastal Mexico and Central America, and along the north coast of South America.

Eastern Willets breed from Nova Scotia south along the Atlantic and Gulf coasts to northern Mexico. Eastern Willets are also resident in the Bahamas and Greater and Lesser Antilles but are migratory elsewhere in the Caribbean. Eastern Willets winter from Virginia south along the Atlantic and Gulf coasts, along the Mexican and Central American Gulf Coast, and in South America to southern Brazil. Because of identification problems, among some observers the distribution of the two subspecies in winter is unclear.

In Massachusetts, Willets are fairly common but local coastal breeders, and fairly common to common migrants. Willets are nighttime migrants that arrive in Massachusetts, especially on Cape Cod and the Islands, in late April. They leave during the last two weeks of August, although some occasionally linger into late October.

Willets are monogamous and usually mate for life. However, males mate-guard females, which suggests that they may occasionally be polygynous. Willets produce a single brood per season. The male’s song is a ringing pill-will-willet that often accompanies wing displays featuring the large white wing stripes. Males sing early in the breeding season to advertise territory and to attract females. Males also have kyah-yak calls that serve many purposes including appeasement and contact. A klink call is used in agonistic and courtship situations. The male’s flight display involves keeping the wings above the body and fluttering. Sometimes the female joins him, with the pair singing duets. The female’s call is lower pitched and flatter. Various “scream” calls are given when attacking or fleeing. Aggressive behavior includes crouched and erect postures, neck outstretched, and lunging or flying at an opponent. In fights, one bird may grab its opponent’s leg or neck. Willets tend to mob predators and are aggressive with other shorebirds. The pair may defend both breeding and foraging territories, which may be completely separated.

Western Willets breed in wetlands, grassland prairies, and on plains near water. Eastern Willets breed in farmland pastures in Nova Scotia, but mostly in salt marshes or on barrier islands along the East and Gulf coasts of the United States. The pair selects the nest site. The male chooses the site and makes a scrape that the female tries out before accepting or rejecting it. The nest consists of a scrape on compressed live grass stems or grass that is brought in and lined with fine grass, twigs, and leaves. Both parents develop brood patches and both incubate the clutch of four olive buff eggs, blotched with dark colors, for three to four weeks until hatching. The chicks are precocial, covered with buff down, eyes open, and feed themselves from the first day. Chicks are able to fly in about a month. When the chicks first leave the nest, the adults accompany, brood, and defend them. Females abandon the chicks after two weeks but the male stays on duty for an additional two weeks until they are independent.

Willets are versatile foragers. They sometimes dash about with their bill open under water, usually catching prey in the tip of the bill. They also forage while swimming and may raise organic substrate in order to forage beneath it. Most often they forage visually during the day or on moonlit nights. On dark nights, they forage tactically, typically by probing the substrate. During the breeding season they take mainly insects, crustaceans, mollusks, polychaete worms, and sometimes small fish. On the wintering grounds they may temporarily defend mudflat territories, where they forage mostly on fiddler crabs.

Egg theft and market gunning during the late nineteenth century reduced the Eastern Willet population to remnants in Nova Scotia and along the East and Gulf coasts. Recovery started in the 1930s but has been slow. The population in Massachusetts did not recover until the 1970s, and in other New England states until the 1980s. Western Willet population declines were due primarily to the conversion of wetlands to farmlands in the interior west. Willets continue to increase in numbers in Massachusetts and elsewhere where suitable breeding habitat is available, and the Breeding Bird Survey suggests that most populations are stable. Hence the Willet, with its flashes of brilliance, appears to have a secure future.

William E. Davis, Jr.


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