Mechanical Sounds and Sexual Dimorphism in the Crested Doradito

Abstract We observed the Crested Doradito (Tyrannidae: Pseudocolopteryx sclateri) in southeastern Bolivia and southern Paraguay. We describe aspects of natural history and morphology not previously reported, which include mechanical sounds, flight display, and microstructural modifications of flight feathers. Mechanical bill-snaps precede and are embedded in the song of P. sclateri. Introductory bill-snap notes may be functionally homologous to vocal notes in the songs of other Pseudocolopteryx species. Males differ from females in their head and bill coloration, intensity of breast coloration, and their shortened and pointed primaries 6 and 7. Males also exhibit microstructural modifications of the bases of primaries 6–9 in the form of open external vanes. Further research on P. sclateri and its congeners is needed to uncover the proximate causes, function, and evolution of some of the unusual tyrannid characters described herein. Sonidos Mecanicos y Dimorfismo Sexual en Pseudocolopteryx sclateri Resumen...