Hummingbirds quickly flap their wings as they move from side to side. In fact, these spectacular birds have the fastest ‘wingbeats’ of all birds, being able to move them about 70 times per second (that is, about 4,000 times per minute). But why do their wings make such a peculiar buzz? A group of researchers from Stanford University (United States) has observed hummingbirds closely to better understand what generated that characteristic sound.
Investigation Development
Scientists created the first 3D acoustic model of flying hummingbirds. To do this, they combined video and audio recordings of the birds in motion, with measurements of the forces generated by the hummingbird wings.
In addition, to capture all the elements of the hummingbird’s flight, the researchers used sensitive pressure plates that measured the strength of the wingbeats, a dozen high-speed cameras, 2,176 microphones, and six hummingbirds that were captured, recorded, and released on the same day, according to the study published in the journal eLife .
In most birds, the buzz you hear is the sound of their downward flight. However, hummingbird wings are shaped like a ‘u’ in the air, so they produce lift both in their downward and upward flight, according to the group of scientists.
Thus, the researchers concluded that hummingbirds hum is produced by differences in air pressure during beats and the speed at which their wings move. On the other hand, the variability in the way the air moves over the feathers, and the overall shape of the wing add nuances to the sound. This produces, for example, that the hummingbird buzz is pleasant for people, unlike the buzz of a mosquito or a fly.
Mating calls
In some species of hummingbirds, males develop mating calls by vibrating their tail feathers. Therefore, according to the researchers, the buzzing of hummingbirds’ wings could also be a form of communication.
However, it is unknown if birds can hear the sound of humming while flying, but it is possible that this could influence the way they interact with each other, as argues Ben Hightower, a researcher at the Stanford School of Engineering.
