Season of moult of African penguins at Robben Island, South Africa, and its variation, 1988–1998

Abstract

Counts of African penguins Spheniscus demersus in immature and adult plumage in the feather-shedding phase of moult were made at Robben Island at two-weekly intervals over a 10-year period between 1988 and 1998. For both age-classes, most birds moulted between November and January, although small numbers moulted throughout the year. In most years, the peak moult was in late November or December. Immature birds had a secondary peak in March. In 1994/95 for adults, and 1995/96 for immature birds, moult was less synchronized than in other years. This probably resulted from oiling of about 2 400 penguins in June 1994, following the sinking of the Apollo Sea. Half of those birds were cleaned and released. Their subsequent moult may have been earlier than normal.