extra-pair copulation

Socially monogamous male birds are predicted to maximise their reproductive success by pursuing extra-pair copulations (EPCs) while engaging in anti-cuckoldry behaviour such as mate guarding. In the stitchbird, Notiomystis cincta, high levels of forced EPCs and a high proportion of nestlings resulting from extra- pair fertilisations lead to the prediction that males of this species should exhibit intense paternity guarding behaviours.

Extra-pair copulation (EPC) occurs frequently in hihi (stitchbird), Notiomystis cincta, resulting in a high rate of extra-pair paternity. It occurs despite resistance by females, and is often witnessed by the paired male. We studied male behaviour to assess whether extra-pair males were timing copulation attempts to coincide with peaks in female fertility, and whether paired males were behaving in ways to reduce cuckoldry. Extra-pair males concentrated copulation attempts at peaks in female fertility.