Vancouver Island is used as a wintering ground by both greater and lesser scaup. They are often found together, but the larger size of the Greater Scaup makes it easy to distinguish between them.
Male Greater Scaup has a large, rounded, glossy blackhead that has a slight green tint. The neck and breast are glossy black, and the flanks and belly are white, sometimes with gray wavy lines on the lower flanks. The back is whitish with fine black uneven lines, and the tail and under tail coverts are black. The wing has a broad white line spanning nearly the entire length of the primaries and secondary feathers. The bill is black with a light blue-gray tip, the legs and feet are gray and the eyes are yellow.
Relatively silent except in display, the male greater scaup utters a soft cooing and whistling notes when he is courting. The female greater scaup is brown with white oval patches around their bills. The female’s bill is similar to that of the male but slightly duller, and the legs and feet are gray. They breed in the boreal forest of the western North American Arctic. It is estimated that three-quarters of the North American population breeds in Alaska. They nest on islands in large lakes and lay an average of 9 eggs
They make extensive flights as they migrate from Alaska to their wintering grounds along the Pacific coast. The greater scaup is a very common bird here on the south coast during the winter months. They dive to feed on aquatic plants and animals. In coastal areas, mollusks constitute the principal diet items. In freshwater habitats, seeds, leaves, stems, roots, and tubers of aquatic plants are important items.