Clutch size usually 6-10 in older adults, 5-7 in yearlings. Adults nest earlier than do yearlings (Duncan 1987). Incubation 21-25 days, by female. Males abandon females early in incubation. Precocial nestlings tended by female, male usually present. Young fledge in about 6-7 weeks. Readily lays replacement clutch if first is lost. In Alaska, nutrient reserves were important in the formation of first clutches, more so than for any other duck species that has been studied (Esler and Grand, 1994, Condor 96:422-432). Northern Alaska: 0.3-1.5 nests per sq km in various locations; 1.0-1.8 nests per sq km in prairie pothole country (see Suchy and Anderson 1987).