The lesser scaup or blue bill, Aythya affinis, is a diving duck that is rare in Utah as a breeder but common as a migrant. In fact, although lesser scaup are often extremely abundant in certain areas of the Great Salt Lake in the fall, only two known breeding records for lesser scaup exist in Utah, with both of those records being from Uintah County. The lesser scaup breeds more commonly in Alaska, Canada, and northern areas of the western and midwestern United States.
Lesser scaup eat both plant and animal material, but the majority of their diet is composed of aquatic insects and other aquatic invertebrates. The species breeds during May and June. Eggs take about three weeks to hatch; average clutch size is ten. Because scaup populations are currently well below their long-term average, the daily bag limit for scaup in Utah was reduced from seven to four in 1999.