Low levels of extra-pair paternity in the long-lived colonial Alpine swift (Tachymarptis melba)

Christoph Meier, Giulia Masoero , Maria Burger, Agnes Schärer, Christophe Sahli, Pierre Bize , Gwenaël Jacob

It has been suggested that a high aerial lifestyle makes it difficult for males to limit mating opportunities for their partners. This would explain the particularly high levels of extra-pair paternity (EPP) observed in several species of swallows and martins (Hirundinidae, Passeriformes), but EPP in the other bird lineages with a high aerial lifestyle, such as swifts (Apodiformes), is largely unknown. Here, we investigated EPP in the Alpine swift (Tachymarptis melba). We found 9 cases of EPP in 9 broods out of 214 (4.2%) nestlings and 87 (10.3%) broods analysed with information on fathers. This low incidence of extra-pair paternities is similar to the only estimate reported so far in Apodiformes (i.e. 4.5% of nestlings in the common swift; Apus apus). We suggest that life‑history traits (biparental incubation, long lifespan, and frequent mate retention across years), rather than their aerial lifestyle, may explain the low incidence of EPP in swifts.