Birds have evolved to produce communication sounds (sonations) with their wings, tail, feet, or beak, dozens if not hundreds of times independently. Ongoing work continues to uncover many new examples of sonations and the physical acoustic mechanisms by which these sounds are produced. The repeated (convergent) evolution of a trait permits sophisticated evolutionary tests of why it evolves. Here, we outline a series of adaptive Questions about the evolution of sonations: Does producing sonations entail tradeoffs with other functions, such as flight? How do sonations co-evolve with production of vocalizations? How do sonations co-evolve with behavior? Compared to vocalizations, do sonations occupy the same functional space as vocalizations? Do sonations occupy the same acoustic space as vocalizations? While each of these questions has already received some attention within individual bird clades, with so many convergent origins across birds, the bigger picture has only begun to appear.