Page "Penguin" Paragraph 22

Penguins form monogamous pairs for a breeding season, though the rate the same pair recouples varies drastically.

Most penguins lay two eggs in a clutch, although the two largest species, the Emperor and the King Penguins, lay only one.

With the exception of the Emperor Penguin, where the male does it all, all penguins share the incubation duties.

These incubation shifts can last days and even weeks as one member of the pair feeds at sea.