Extra-pair paternity in seabirds: A review and case study of Thin-billed Prions Pachyptila belcheri

Abstract

Seabirds are long-lived birds that exhibit very high levels of parental investment, and male parental care is indispensable. Seabirds have comparable breeding and life history parameters, being colonial, long-lived, and exhibiting little or no sex dimorphism. It is thought that these characteristics explain why seabirds exhibit a uniformly low level of extra-pair paternity. However, among the relatively few seabirds that have been studied to date, some regularly engage in extra-pair copulations, and the reasons for such inter-specific variability remain unclear. We here analyse paternity in a small sub-Antarctic seabird, the Thin-billed Prions Pachyptila belcheri, using species-specific microsatellites as genetic markers. We found that 7 of 34 chicks (21%) were not fathered by the male pair partner. This value is among the highest recorded for seabirds, and it now needs to be established if these result from forced copulations as suggested for some albatross species, or female cuckoldry. © 2011 Dt. Ornithologen-Gesellschaft e.V.