Levels of extra-pair paternity are associated with parental care in penduline tits (Remizidae)

In most passerine birds, individuals attempt to maximize their fitness by providing parental care while also mating outside their pair bond. A sex-specific trade-off between these two behaviours is predicted to occur, as the fitness benefits of extra-pair mating differ between the sexes. We use nest observations and parentage analysis to reveal a negative association between male care and the incidence of extra-pair paternity across three species of penduline tit (Remizidae). This provides evidence of a trade-off between these two behaviours, possibly due to the devaluing of paternal care by extra-pair offspring.