High-frequency vocalizations and hearing in hummingbirds: what we know and opportunities for the future

Hummingbirds possess many distinct traits that make them stand out among birds. Among those features is the use of high-frequency vocalizations as part of the vocal repertoires of some species. These frequencies are much higher than what most birds are known to produce and hear. However, the mechanisms for the production and perception of these vocalizations are yet to be elucidated. This Review summarizes what we have learned about high-frequency vocalizations in hummingbirds in the past decade, as well as potential mechanistic explanations for this behavior. We aimed to compile a broad understanding of the potential proximate and ultimate mechanisms for such extended vocal production and auditory perception, emphasizing the need for comparative studies. By understanding how hummingbirds have adapted to communicate in complex acoustic environments, we may be able to predict how a rapidly changing environment will influence species with extraordinary sensory capabilities compared with other closely related taxa.