White-winged Scoter Life History

Habitat

Habitat Lakes and Ponds

White-winged Scoters breed in the boreal forest, usually not far from lakes and ponds surrounded by shrubs, and much less often in tundra. These remote lakes are usually 125 acres in extent or larger and surrounded by species of raspberry, gooseberry, snowberry, rose, nettle, or reed. Many of the lakes have sandy bottoms. The brushy areas around the lakes are ideal for concealing the nest, which is sometimes 300 feet or so from the lakeshore. After breeding, some White-winged Scoters remain to molt on the nesting lake, while others uses larger lakes, rivers, or even open saltwater habitats. In winter, some White-winged Scoters remain inland, especially on the Great Lakes, but most move to Atlantic and Pacific coastal areas, where they use relatively shallow areas with sandy or stony bottoms.

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Food

Food Aquatic invertebrates

White-winged Scoters eat mollusks, crustaceans, fish, and insects; plant matter makes up a very small part of their diet. During the breeding season, in freshwater environments, they eat mostly crustaceans and insects, along with small amounts of aquatic plants such as pondweed or bulrush. In the nonbreeding season, spent mostly in saltwater habitats, they eat mostly mollusks including razor clams, quahogs, rock clams, wedge clams, oysters, dogwinkles, periwinkles, mussels, scallops, yoldias, nassas, and sometimes small fish such as sandlance. They capture prey by diving, then swimming to the bottom, where they grasp the prey with the bill. Because they eat large quantities of bivalves such as mussels, they must often pry the prey from the sand or from its attachment to the rock (or other submerged object), which they do by holding themselves in one place—essentially hovering underwater—and pulling the shellfish from side to side until it comes loose. Some birds spend more than a minute underwater securing prey. They usually swallow the prey whole while still underwater, but they may bring larger prey to the surface to manipulate in the bill before they swallow it.

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Nesting

Nest Placement

Nest Ground

Females select a depression in the soil beneath heavy, usually thorny vegetation such as berry bushes or roses, often rather far (300 feet) from the nearest lake.

Nest Description

Females build a fluffy, bowl-shaped nest using their own down feathers, grasses, and twigs. The nests average about 7.9 inches across and about 3.5 inches tall.

Nesting Facts

Clutch Size:6-16 eggs
Egg Description:

Creamy buff or light pink.

Condition at Hatching:

Downy and eyes open. Leave nest soon after they dry. Feed themselves immediately.

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Behavior

Behavior Surface Dive

White-winged Scoters perform group courtship displays while still on the wintering grounds, as many ducks do. In the case of White-winged Scoters, one of the displays occurs in group flights. A group of males and at least one female rise up steeply into the air, often in erratic patterns, then suddenly stall, with spread tails and splayed feet, and dive downward together toward the water. Some males even flip upside down during part of the dive! On the water, compared to Surf and Black Scoters, White-winged Scoters are less boisterous in displaying. Males sometimes extend the neck upward and forward, flap the wings, or rear up and raise the bill. As the breeding season nears, males display more vigorously, often performing displays in which they drink water, preen, or bathe themselves by splashing with the wings. An interested female responds by dipping the bill and making a drinking motion, or by raising the bill quickly several times. Most White-winged Scoters appear to be already paired when they arrive on the breeding grounds, and the species seems to be monogamous in its mating system. Paired males drive rivals away from the female, who also resists attempts of other males to court or copulate. The female alone incubates and tends the ducklings, but the male sometimes stays with the female even after she lays eggs. After breeding, White-winged Scoters gather in small flocks and travel along rivers toward ocean coasts. They winter in small to large flocks, often among other scoter and sea duck species.

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Conservation

Conservation Low Concern

White-winged Scoters are fairly common, but biologists know very little about their population trends. Partners in Flight estimates a combined global breeding population of White-winged, Stejneger’s, and Velvet Scoters of 400,000 and rates White-winged Scoter a 13 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. White-winged Scoters are hunted in the United States, with populations and totals monitored by the U.S. Fish and Wildlife Service. Reports of hunting activity provide data for White-winged, Surf, and Black Scoters combined, and indicate that about 49,000 scoters are shot during regular hunting seasons each year. Destruction and modification of large areas of its nesting habitat in the boreal forest would harm populations, as would oil spills and other forms of pollution in the marine environments where they winter. Some studies have revealed high levels of mercury, lead, and cadmium in this species’ organs, probably because these metals occur in high concentrations in shellfish such as blue mussels, a favored winter prey species. The main conservation priority in the case of White-winged Scoter is basic research on its populations.

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Credits

Brown, P. W. and L. H. Fredrickson (2019). White-winged Scoter (Melanitta deglandi), version 1.1. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.whwsco4.01.1.

Brown, Patrick W. and Leigh H. Fredrickson. (1997). White-winged Scoter (Melanitta fusca), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Raftovich, R. V., S. C. Chandler, and K. K. Fleming. (2018). Migratory bird hunting activity and harvest during the 2016-17 and 2017-18 hunting seasons. U.S. Fish and Wildlife Service, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Wilson, W J. (1980). Inverted flight of White-winged Scoters during courtship flight. American Birds 35: 746-747.

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