Vegetation lined with down.
Molluscs, crustaceans and some small fish.
Their plumage varies more than that of any other duck, seasonally, by sex, and by age.
Male Summer plumage:
head, chest, and wings. Gray face patch surrounding eyes. Upper back
feathers long, and buffy with black centers. Central tail feathers very
White head and neck. Gray patch around the eyes. Large black spot
extending from cheek down sides of neck. Black band across lower neck
and breast. Back black. Long, gray upper back feathers. Long, black
central tail feathers. Eyes dull yellow-brown.
Female Summer plumage:
Mostly dark head and neck, with white around eyes, extending in a thin
line toward the ear. Back and breast are variably brown or gray. Eyes
Female Winter plumage: White head and neck. Round dark brown cheek patch. White belly. Variably brownish gray crown, breast, and back.
Juvenile has dark brown head, white or pale brownish gray face, white
belly, and brownish gray upperparts, breast, and upper belly. Immature
resembles adult of same sex.