One of the most impressive scenes in the world of birds is a peacock displaying its impressive, iridescent feathers, technically known as its train. While the female peahen looks on, the peacock spreads his train out and ruffles it back and forth as the sun highlights the red, blue, and green within the feathers. But these iconic trains are only half of the story of how the boys impress the ladies. Both male and female peafowl sport crests on their heads, small feathers that stick straight up, like a Mohawk. "The crest feathers that actually give the peacocks' their Latin name, they're called Pavo cristatus, the crested pheasant. And so I was intrigued by the fact that people didn't really know what the function of these crests were." A biologist might see those feathers and assume they are visual signals, but as a physicist, Kane had a different idea. "We were curious in my laboratory about whether the preferred vibrational properties of the crest feathers might, by any chance, agree with the preferred vibrational properties of this train-rattling display that the males do. So Kane and her colleagues exposed crest feathers from preserved, dead peafowl to simulated displays of male and female social behaviors, like wing-shaking and train-rattling. "And so we were just gob smacked to find out that in fact they did agree." What all that means is that the peafowls' head crests are specifically tuned to the vibrations produced by the train-rattling of its own species.