Emperor penguins breed in the middle of the Antarctic winter. To begin the cycle, they must leave the sea and cross 200 kilometres of sea ice to their breeding sites, where they mate. There they stay until the egg is laid six weeks later. The female then treks back across the widening sea ice to feed at sea while the male stays put, incubating the egg on his feet. He remains for nine weeks, huddling with the others against air below minus 60º C and winds above 180 kilometres per hour. The fast ends when the female returns to take a turn once the chick hatches, by which time the male is half the penguin he used to be.