Complex male display and female choice in the spotted bowerbird: specialized functions for different bower decorations

Abstract Male bowerbirds build and decorate bowers to attract females as copulation partners. Spotted bowerbirds, Chlamydera maculata , are atypical in having widely spaced display sites, bowers that are greatly diverged from those of closely related species, and extremely intense, aggressive displays. Results from the continuous monitoring of bowers show that (1) a few males account for the majority of matings, (2) the two most common decoration types, bones and glass, explain a large proportion of the variation in male mating success and (3) large inter-bower distances relate to low levels of decoration stealing and bower destruction. Components of male mating success, male ability to attract female visitors to the bower, and male courtship success correlate respectively with counts of bones and glass. Bones are spread widely around the bower and glass is placed close to it supporting the hypothesis that bones act to attract females towards the bower and glass functions later to stimulate females in the bower. This temporal sequencing of courtship functions represents a novel explanation for the evolution of complex male display traits.