Plumage aberrations in Macaroni Penguins Eudyptes chrysolophus at sub-Antarctic Marion Island

Plumage aberrations, such as leucism, isabellinism, albinism and melanism, are hereditary and are caused by irregularities in the formation of melanin. This paper presents opportunistic observations of plumage aberrations in 15 Macaroni Penguins Eudyptes chrysolophus at sub-Antarctic Marion Island during 2008–2016. Across five colonies, full and partial leucism, isabellinism and partial melanism were recorded. Plumage aberration in Macaroni Penguins is rarely reported elsewhere in the world. The relatively high number of recorded individuals at Marion Island, in conjunction with limited mixing between global Macaroni Penguin colonies, suggests that a relatively high proportion of the population is entrained with this genetic predisposition.