Extra-pair mating opportunities mediate parenting and mating effort trade-offs in a songbird

In socially monogamous species with bi-parental care, males may face a trade-off between providing parental care and pursuing extra-pair matings. The “parenting-mating trade-off” hypothesis predicts that high-quality males – who have greater potential to gain extra-pair matings, e.g. larger males usually win the competition for extra-pair mating – should reduce parental care and spend more time looking for extra-pair matings. However, the trade-off between parenting and mating efforts may be complicated by variation in the availability of extra-pair mating opportunities. By using field data of hair-crested drongos (Dicrurus hottentottus), a species exhibiting bi-parental incubation behavior, collected in central China from 2010 to 2017, we tested whether the potential negative relationship between male quality and paternal care was dependent on the number of nearby fertile females. We found that male drongos mainly seek extra-pair matings during the incubation period and high-quality in...