The clutch size of Macaroni and Rockhopper Penguins

Abstract

Published claims that Macaroni Penguins Eudyptes chrysolophus and Rockhopper Penguins E. chrysocome lay clutches of one or three eggs are reviewed in the light of current knowledge of the breeding biology of these and other species of penguins. It is concluded that the clutch size of these Eudyptes penguins is invariably two eggs, that one-egg clutches are usually reported because the loss of the A egg was not noticed and that most three-egg clutches are the result of adoption of eggs.