Breeding begins late May in south to June in north. Egg laying peaks late June-early July at Arctic Natl. Wildl. Ref. Clutch size often 5-11 (usually 6-8). Incubation 25-26 days, by female (male departs). Most eggs hatch in 2nd half of June in Beaufort Sea area. Nestlings precocial and downy. Young tended by female, independent in about 5 weeks (Harrison 1978). Does not breed until at least 2 years old. According to Bellrose (1980), nest success is around 70% and brood survival data are lacking. Frequently nests in clusters or colonies. Nests per sq km in northern Alaska: 0.6-1.8 in different areas (Johnson and Herter 1989).