Dominance status, mating strategies and copulation success in cooperatively polyandrous white-winged trumpeters, Psophia leucoptera (Aves: Psophiidae)

Abstract

In groups of white-winged trumpeters, dominant and subordinate males used different strategies to obtain copulations with the dominant, breeding female. The dominant male initiated copulation attempts slowly and often copulated when subordinate males were standing nearby; in contrast, subordinate males tended to copulate rapidly and surreptitiously, taking advantage of moments when the dominant male was relatively far from the female or engaged in an activity that made it difficult for him to watch the female. The dominant male usually interrupted subordinates' copulation attempts aggressively and always interrupted alone. Subordinate males, however, generally interrupted the dominant simply by approaching him, and collaborated in 19% of their interruptions. Although the dominant male obtained significantly more successful copulations than did subordinate males during the breeding female's fertile period, subordinate males still accounted for one-third of the successful copulations during this period. While relatively few birds or other vertebrates have been reported to breed polyandrously, it is suggested that the frequency with which multiple males sire offspring within a group may be underestimated because of the difficulty of observing copulations by subordinate males in many multi-male groups.