Study population
The data we present were collected as part of a long-term individual-based study of a mono-specific common tern colony located on six artificial concrete islands at the Banter See (53°36′N, 08°06′E) in Wilhelmshaven, Germany. Fledglings from this colony have been marked with metal rings since 1984, and subcutaneously injected with transponders since 1992 (Becker & Wendeln 1997). This transponder-marking combined with placement of antennae on elevated platforms on the edges of the colony site and around each nest during incubation (shared between both parents), allows for a well-described family structure of all philopatric birds (e.g. Moiron et al.2020).