Hummingbird Feathers Reverberate Like Violin Strings Creating Unique Songs

Clark wrote numerous papers on hummingbird tail resonance. He has also hypothesized in prior publications that hummingbirds may have evolved this singing style before they found their vocals.

Clark wanted to know how these feathers sang in his latest paper. He knew these feathers made noises. He knew they only made those sounds at certain wind speeds.  

His question now was what sounds these feathers made. Do feathers flutter to produce resonant frequencies? Does the feather vibrate like a violin string or randomly?

Simply described, resonant frequencies are the object's easiest vibrations. In our violin example, each string vibrates at resonant frequencies. The instrument's body and air do too. But we'll concentrate on strings. Combining them produces violin resonant frequencies that sound louder.

Clark again used feathers in a wind tunnel in this study. This time, he and his colleagues calculated the feather's intrinsic resonance frequency from its shape.

Feathers have intrinsic resonance. Everything does. However, Clark and his team intended to test the wind tunnel for those resonant frequencies. Did the feathers flutter as expected by structural resonant frequencies?

They did, like guitars and violins. The researchers said, “We conclude flutter occurs when airflow excites one or more structural resonance frequencies of a feather, most akin to a vibrating violin string.”