Dominance, Food Acquisition and Reproductive Success in a Monogamous Passerine: The Jackdaw Corvus monedula

Abstract

By manipulating the density and area of a food supply of grain offered to wild Jackdaws we showed that individuals in flocks varied in their ability to acquire food through direct physical competition, and that the relative pay-offs to individual competitors varied according to the distribution of the resource. There was a disproportionate ability of some individuals to occupy preferred flock positions or feeding sites and higher ranking males had greater access to clumped food. Rank was positively correlated with the more efficient provisioning of offspring and the raising of larger annual broods, but reproductive success and social status were also strongly dependent on age. Our results provided evidence that attributes of dominance (e.g. fighting ability) are valuable for maintaining access to increasingly restricted food supplies. Since the rank of an individual is explained at least in part by age we discuss the consequences of this for the durability of the pair-bond and life-time reproductive success.