There is more to a peacock's feather-shaking technique than just an ostentatious display of iridescent eyespots to attract a mate, a new report has revealed.
Animals often display their body parts such as head crests and horns as a form of sexual display. Peacocks woo a mate by fanning out their feathers and shaking them. Researchers from the University of British Columbia in Canada found the biomechanics that suggest that it is not just the visual display of its stunning, iridescent eyespots that attracts a potential mate.
Peacocks also produce vibrations at resonance when shorter tail-feathers strike the longer feathers. The vibrations create an illusion that everything is moving except for the eyespots on top.
By doing a microscopic study of the feathers, the scientists saw that the characteristic eyespots of peacocks are held together by microhooks while they wiggle and rattle their tails. This causes the surrounding filaments of the eyespots move along with the other feathers as the eyespot center remains still - eyespots then appear iridescent.
Along with the movement, the feather-shaking vibration occurs at a frequency that is almost similar to the feather's usual frequency.
By studying the high-speed video capture of the train-rattling display and comparing it with individual feathers studied in the laboratory, the physicists were able to identify that frequencies of train feathers were at resonance.
The physical properties of the peacock's feather allow them to strum at a rhythm that matches their feather train's natural frequency. Study author and applied physicist Suzanne Amador Kane likened the action to a child on a swing.
"If you just pull them back and let them go, they swing at a pre-set frequency," explained Kane. "The rate at which they swing back and forth is set by the mechanical properties of the swing and not how you're pushing them."
The team also noted that peacocks with longer tail feathers are able to shake faster, suggesting that they have powerful muscles that make them more attractive to peahens.
The study was published in PLOS ONE on April 27.