Subordinates benefit from exploratory dominants: response to novel food in cooperatively breeding carrion crows

摘要

Kin-based societies typically form when offspring prolong their association with the parents. It has been suggested that offspring delay natal dispersal because of the benefits that such association conveys. We found that in cooperatively breeding carrion crows, Cbrvus corone corone, risk-prone fathers facilitated their offspring's access to novel and potentially dangerous food. In crow groups, dominant breeding males, which share food nepotistically with their offspring, made the first contact with novel food, followed by male immigrants, whereas retained offspring and breeding females were last. This order mirrored the dominance ranks in the group, but it was unlikely to be enforced through social interference. In groups that were simultaneously presented with two identical novel food sources that could not be monopolized by one individual, subordinates only used the one that was first explored by the dominant male. This suggests that foraging decisions in crows were affected by the fear of the novel food and that the explorative behaviour of the dominant breeding male provided cues that helped subordinates to overcome their neophobia. In their natal territory, inexperienced offspring therefore gained access to food without incurring the risk of exploring. For a foraging opportunist such as the carrion crow, this may convey survival benefits that could play a role in driving delayed natal dispersal.