Parental interference in sibling aggression in birds: What should we look for?

Abstract

In many avian species, older nestlings within a brood may decrease the fitness of younger siblings by aggression or competition. While such a situation suggests a potential parent-offpring conflict, it is often assumed that parents condone sibling aggression because there are few reports of adult birds intervening in fights between their young. However, parent bald eagles (Haliaeetus leucocephalus) interfered in 9% of bouts of sibling aggression using a variety of tactics not previously reported for birds. A review of the literature revealed additional behaviours that may be used to mitigate sibling aggression. We propose that parents may use “general remedial𠇍 behaviours as a long-term strategy to ensure adequate resources to disadvantaged offspring, and “acute responses” involving physical contact, distraction, or deception, to halt particular aggressive acts.