Introduction

Bowers are structures built by a mere 17 or 18 species of birds belonging to only a single family (Ptilonorynchidae) confined to New Guinea and parts of Australia (Gilliard 1969, Cooper & Forshaw 1977, Sibley & Monroe 1990). These structures would hardly seem candidates for dominating a whole chapter, but for two things. The first is the complexity and to our eyes even beauty of the structures built by some species. Diamond (1987) describes the structure built by the vogelkop bowerbird (Amblyornis inornatus) as ‘the most elaborately decorated structure erected by any animal other than humans’. The second is that, as Darwin proposed in The Descent of Man (1871), the evolution of the elaborate structure of these bowers is the consequence of sexual selection through female choice.

Bowers are not nests; they are built only by males of this family for the purpose of attracting mates. Females alone build nests, in quite separate locations. Debate and active experimentation surround the more general question of female assessment of male quality and the effect this will have on male characters through sexual selection (Andersson1994). One purpose of this chapter is to show how studies on bower construction, and to a lesser extent on nest building, are making a significant contribution to the understanding of sexual selection through female choice. The other is to examine how bowers actually function to enhance male mating success.