Extra-pair copulation and paternity defense in the hihi (or stitchbird) Notiomystis cincta

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. Paired males attempted to defend their paternity by defending an area around the nest site, by territorial calling and displacing intruding males. The frequency of EPC attempts varied between nests and this variation mirrored closely the variation in the percentage of extrapair paternity. Potential additional paternity guards, such as frequent copulation, did not occur in this population.