The Lesser Scaup is one of the most abundant diving ducks in North America and a familiar sight on Michigan's lakes and Great Lakes bays during migration, where great rafts of them ride the water and vanish in synchronized dives. The drake shows a dark head with a faint purple gloss, a pale gray back, a black chest, and a bright golden eye; the hen is brown with a crisp white patch at the base of the bill. A peaked, slightly angular head and small size help separate it from the very similar Greater Scaup.
Scaup dive to feed on mollusks, aquatic insects, and crustaceans on lake and river bottoms, and the Lesser Scaup in particular gathers in enormous migratory flocks. Michiganders know it mainly as a migrant and winter bird, when "bluebills" (a nickname from the pale blue-gray bill) crowd open water. Distinguishing Lesser from Greater Scaup — by head shape, gloss color, and size — is one of the classic identification puzzles of the state's waterfowl season.
Dives to feed on mollusks, aquatic insects, crustaceans, and other bottom invertebrates, along with the seeds and parts of aquatic plants. On the Great Lakes it takes many small mollusks, foraging in rafts that dive together on lake and bay bottoms.
Lesser Scaup is smaller with a peaked, slightly angular head that often shows a purplish gloss, while Greater Scaup is bigger and rounder-headed with a greenish gloss and typically more white in the wing in flight. The differences are subtle and require care.
The nickname comes from the pale blue-gray color of the bill, shared by both scaup species. It is a common gunning and birding term for these diving ducks.
During spring and fall migration, when large rafts gather on lakes and Great Lakes bays, and through winter on open water. They are far less common as breeders in the state.
First-winter birds are brown with a whitish blaze at the base of the bill, and young males gradually acquire the adult's dark head and pale gray back over their first winter. Head shape separates them from Greater Scaup better than color does.
A raft. Lesser Scaup form some of the biggest rafts on the Great Lakes, occasionally tens of thousands of birds packed together offshore, and the raft drifts and dives as a coordinated unit.
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