Data set for: The unique mating system of Tooth-billed Bowerbirds and bower evolution in the maypole-building clade

Abstract. Bowerbirds have received much attention as textbook examples of intense sexual selection because most species evolving the remarkable behaviour of building elaborate bowers, which they decorate with collected objects and use as show grounds for complex courtship displays. What has received less attention is the variation among bowerbird species that do not show the extreme sexual behaviours of other polygynous species in this family. There are few hypotheses or comparative behavioural studies that explain why closely related species with non-resource-based mating systems might differ. The Tooth-billed Bowerbird (Scenopoeetes dentirostris) is unique among the polygynous bowerbird species because males form exploded lek aggregations, do not build any structure on their courts, and have almost continuous loud vocal displays throughout the day. We show that Tooth-bills differ from other bowerbirds by having unusually brief courtships, with females landing on courts already in a preliminary receptive position. Males then aggressively capture and copulate with visiting females, limiting female opportunity for mate assessment of on-court displays. Despite this, we found high variance in male mating success, with males at lek centres having the highest number of copulations. These results suggest that the position on leks allow for female assessment of male quality. Here, we propose that the exploded lek mating system of Tooth-billed Bowerbirds represents an early adaptation among maypole-building bowerbirds that could not be replicated in the habitats of later-derived species of this clade, and we explore the likely causes of these differences.