Genetic monogamy in two long-lived New Zealand passerines

High rates of extra-pair paternity (EPP) can be relatively common in passerines whereas low rates or absence of EPP are often associated with taxa that are long-lived and exhibit obligatory paternal care. We examined EPP in an underrepresented category: passerine species with relatively long life spans (or low annual mortality rates). Specifically, we studied EPP in New Zealand saddlebacks Philesturnus carunculatus and robins Petroica australis, two species with unusually low annual mortality rates (6.5 11% and 10 20% respectively). No EPP (0%) was detected in saddlebacks (39 pairs, 202 offspring) and only one case of EPP (1.9%) was detected in robins (54 pairs, 198 offspring). Genetic monogamy in these passerine species supports the hypothesis that low annual mortality rates play an important role in explaining variation in rates of EPP across species.