Perch height predicts dominance rank in birds

Dominant individuals within animal groups will frequently place themselves in the most beneficial position for maximal protection against predation, and for foraging benefits. Higher perches are generally associated with reduced predation risk in birds, so we hypothesized that dominant birds will preferentially place themselves on higher perches, with subordinates typically perching at lower heights. We tested this hypothesis by determining the dominance hierarchy in two populations of captive birds (Homing Pigeons Columba livia and Great Cormorants Phalacrocorax carbo), and relating rank within the dominance hierarchy to observed perch height preferences. We found that perch choice was significantly repeatable in pigeons, and that more dominant individuals of both species selected higher perches. Higher perches are also likely to facilitate the display of aggression to other group members, while facilitating early detection and escape from potential predators. It is likely that this perch fidelity and height choice may be exacerbated in captive scenarios due to a closed population and limited area.