The female lays her eggs in April, May, and June, and the male then takes full responsibility for the incubation and care of the offspring. He incubates 9-20 eggs for 56 days, with no eating, drinking, or defecating during this time, losing up to 20 percent of his body weight. Once the chicks hatch, the male becomes very aggressive, often driving away the female. Males stay with the young for five to seven months.