Lumbering the gauntlet: Cape Gannet fledglings killed by African Penguins

Abstract

This account presents the first known observations of Cape Gannet Morus capensis fledgling mortalities as a result of aggressive nest defence behaviour by African Penguins Spheniscus demersus. Observations were conducted in 2013 on Bird Island, Algoa Bay, South Africa – the world's largest breeding colony of Cape Gannets. Twentyeight attacks were witnessed between 21 March and 18 May 2013 of which 16 resulted in mortality. The absence of previous observations of this phenomenon may be due to an unusually high proportion of African Penguin chicks being present relatively early on in the breeding season, associated with a potential for increased nest defence at this stage, and a larger number of gannet fledglings that year compared to previous years over the same period.