THE DISPLAYS AND SONATIONS OF THE BLACK-CHINNED HUMMINGBIRD (TROCHILIDAE: ARCHILOCHUS ALEXANDRI)

Studies on the sonations (nonvocal communicative sounds) of birds have revealed a wide diversity of mechanisms and functions. We describe the kinematics and sounds of the display dive and shuttle display of the male Black-chinned Hummingbird (Archilochus alexandri). Males produced an integrated series of trilled and tonal sounds during their displays. Through a combination of experiments on wild birds, experiments on isolated feathers in the laboratory, and comparisons between high-speed video and audio recordings, we show that the display sounds are sonations produced by feathers. The timing of the trilled sounds during both the shuttle and dive displays corresponded to the wingbeat kinematics, which suggests that they are produced by the wings. These trills were qualitatively similar to the wing trills reported for other species of hummingbirds, but the mechanism of sound production remains unclear. The production of the tonal sounds during the display dive corresponded to tail spreads, and experiments show that this sound was produced by fluttering of the tip of the outer tail feather, rectrix 5 (R5). Hummingbirds in the genus Calypte also produce dive sounds with R5, but sound is instead generated by the trailing vane of the feather. Calypte and Black-chinned Hummingbirds differ in the shape of the tip of R5, and we hypothesize that this difference in shape affects which mode of flutter is activated by airflow. Received 12 December 2009, accepted 24 June 2010.