Low incidence of extra‐pair paternity in the colonially nesting common swift Apus apus

Abstract

The frequency of extra‐pair paternity in a wild colony of swifts Apus apus was determined by multilocus DNA fingerprinting in two successive breeding seasons. The data were used to examine the expectation that extra‐pair paternity is frequent in colonial‐nesting species, either for proximal reasons such as the increased opportunity for extra‐pair matings, or because extra‐pair matings are important in the evolution and maintenance of coloniality. Forty‐two broods containing 88 chicks were analysed. The genetic analysis revealed four cases of extra‐pair paternity (4.5% of chicks) from four (9.5%) nests. Rapid mate‐switching was considered unlikely to be the cause of extra‐pair paternity since three of the cases were in the nests of previously established breeding pairs. Extra‐pair copulations were not observed, but were assumed to be the cause of extra‐pair paternity. The data show that high levels of extra‐pair paternity are not an inevitable feature of high‐density nesting.