Bird Observer - The New England Birding Journal

Bird Observer

The Birding Journal for New England

December 2018

Vol. 46, No. 6

Front Cover: December 2018

Surf Scoter by Barry Van Dusen

An artist who has created many of our covers, Barry Van Dusen lives in Princeton, Massachusetts, and is well known in the birding world. Barry has illustrated several nature books and pocket guides, and his articles and paintings have been featured in Birding, Bird Watcher's Digest, and Yankee Magazine as well as Bird Observer. Barry's interest in nature subjects began in 1982 with an association with the Massachusetts Audubon Society. He has been influenced by the work of European wildlife artists and has adopted their methodology of direct field sketching. Barry teaches workshops at various locations in Massachusetts. For more information, visit Barry's website at http://www.barryvandusen.com.

Surf Scoter

The Surf Scoter (Melanitta perspicillata) is a breeding and wintering endemic species to North America, yet until the 1980s and 1990s was our most poorly studied duck species. Adult males are distinctive, beautiful birds with glossy black plumage highlighted with white patches on the forehead and nape; the swollen wedge-shaped bill, which looks orange from a distance, is red, yellow, white, and black. First winter males are browner and their white head patches are somewhat muted. Females have three variable white patches on the nape and face, including a distinctive vertical patch at the base of the bill that helps to separate them from female Black and White-winged scoters. Juveniles resemble females but have whitish bellies. Surf Scoters are monotypic, having no recognized subspecies.

Surf Scoters breed on tundra lakes scattered from northwest Alaska across northern Canada, with the largest concentrations east of Hudson Bay. They don't breed until their second or third year, and young nonbreeding birds occasionally summer along the coasts of North America. Surf Scoters winter along the Pacific Coast from the Aleutian Islands south to Baja and northwestern Mexico, and in the east from Nova Scotia south to Florida and the Gulf Coast through East Texas. On the East Coast, most Surf Scoters congregate in staging areas along the Gulf of St. Lawrence from April to mid-May on their way to the breeding grounds. After breeding, males that bred in the east concentrate at staging sites on the coast of Labrador and the St. Lawrence Estuary to molt, where they are joined eventually by females and juveniles. Males, females, and juveniles migrate south at different times. In Massachusetts, Surf Scoters are considered uncommon to occasionally abundant winter residents, but are common spring and abundant fall migrants along the coast. They rarely occur inland. Most fall migration occurs in October, and spring migration takes place from April through early May.

Surf Scoters are monogamous and pairs may stay together for more than one breeding season. Pair formation takes place on the wintering grounds or at migration staging areas, so pairs are already formed when they arrive on their breeding grounds. Most courtship displays occur in the water or in the air. In one series of displays, the male swims back and forth, neck erect, and dips his bill in the water. In front of the female, the male may combine headshaking and breast-preening motions and utter a gurgling sound. In another display, the male tosses his head back and lifts his chest out of the water. In still another display, upon landing after a short flight, the male may lift his neck up and raise his wings to the vertical. Sometimes the male performs a more elaborate display where he raises his tail and turns his head while pressing his bill into his breast feathers. Females display by raising their head, sometimes with beak open, and giving rasping calls. Surf Scoters are generally silent, although in flight their wingbeats produce a whistling sound.

Surf Scoters can be aggressive during the breeding season. They often stretch their necks forward as a threat display. Both males and females will attack when an unpaired duck approaches their mate on their breeding lakes. Males sometimes fight over females and females will attack adults approaching their brood.

Surf Scoter nests are usually located on an island in a lake, where they tend to be well concealed under a conifer branch or a fallen tree. The female probably is responsible for making the nest bowl in the ground. The nest is lined with down and any vegetation that is available, such as moss, pine needles, or twigs. Only the female develops a brood patch and she alone broods the clutch of seven to eight creamy white eggs for about one month until hatching. The chicks are precocial and are covered with down and their eyes are open at hatching. The female leads the chicks to water, where they immediately can feed themselves. Females tend their own chicks, but in areas where breeding densities are high, brood creches may form containing 30 or more young. Males leave the nesting lakes after only a month and females eventually abandon the young before they can fly. The young birds can fly when they are about two months old and they move to staging and wintering areas in groups without adults.

Surf Scoters forage by diving, sometimes partially using their wings for "underwater flying." Or they may use only their feet for propulsion, either with wings folded or partly extended and used as rudders. When molting or wintering in salt water, Surf Scoters forage primarily on mollusks, including mussels and clams, and in spring migration may opportunistically also take herring eggs. At their freshwater breeding grounds they feed on a variety of invertebrates, mainly crustaceans and insects. One study of Surf Scoters wintering along the New Hampshire and Massachusetts coasts showed that they mostly preferred Arctic wedge clams, but also Atlantic razor clams and blue mussels.

Surf Scoters are preyed upon by a variety of animals. Loons will take ducklings; therefore, a female Surf Scoter will lead her brood to shallow water if a loon is about. Bald Eagles are also predators at molting and staging areas. Nest predators include foxes, mink, crows, and ravens. Weather in the far north sometimes also results in mortality during nesting. Surf Scoters are heavily hunted in some areas, are vulnerable to oil spills, and get caught in fish nets. Nonetheless the remoteness of their breeding areas gives hope that they will continue to grace our coastal waters.

William E. Davis, Jr.








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