Cases of foreign egg adoption by Brown Skuas Stercorarius antarcticus on Marion and Gough Islands

Ground-nesting birds, such as large gulls and skuas, are known to include a variety of items in their nests as pseudo-eggs, as well as to adopt the eggs of conspecifics or other species. Three hypotheses have been proposed to explain this phenomenon: incubation stimulus, mistaken food, and mistaken egg hypotheses. Of 657 Brown Skua Stercorarius antarcticus nests surveyed on Marion Island during the 2017/18 breeding season, two instances of egg...