The King Penguin is able to breed at three years of age, although only a very small minority actually do then; the average age of first breeding is around 6 years. The King Penguin has an unusually prolonged breeding cycle, taking some 14–16 months from laying to offspring fledging. The reproductive cycle begins in September to November, as birds return to colonies for a prenuptial moult. The female penguin lays one pyriform white egg weighing 300 g. The egg is incubated for around 55 days with both birds sharing incubation in shifts of 6–18 days each. By April the chicks are almost fully grown, but lose weight by fasting over the winter months, gaining it again during spring in September. The lifespan is typically 20 years in the wild.