Copulations with a nestling by an adult care-giver in a kin-living bird

Abstract

Adult sexual interest in dependent young, such as lactating pups or nestlings, has been reported in a few species, with copulations with related dependent young being, at best, extremely rare. Here we document two events of copulations on a nestling by an adult caregiver in a group of kin-living and cooperatively breeding carrion crows Corvus corone. Copulations, as well as other unusual rough actions toward the nestling, occurred within a short time-span characterized by intense conflict among adult group members, suggesting that stress could trigger such behaviours toward the brood.