During courtship, king penguin males come face-to-face and flaunt their bills to possible mates. The strong contrast of the black background of their bills is believed to augment UV light reflection. During courtship, a male penguin will find the smoothest pebble to give to a female as a gift. If she likes the offering, she'll place it in the nest and the two will continue building up their little pebble mound in preparation for the eggs. King Penguins are “serially monogamous” – they mate with only one mate per season, working with their mate to hatch the egg and care for the chick. However, unlike some other species of penguin, they're not so likely to return to the same mate the next year – about 70% will find a new mate the following season.