Many of us feel a buzz when approached by a charming and attractive stranger, but not in such a literal sense. When a peacock rattles his opulent train feathers at a female of the species, it makes a sound at a specific frequency – causing the crest on her head to vibrate energetically.
Peafowl () are famous for the spectacular train of feathers worn by males. The feathers are brightly coloured and have iridescent “eyespots”. Males display them to attract females.
In 2016, physicist at Haverford College in Pennsylvania and colleagues showed that there might be more to the display than just looks. They found that peacocks rub their tail feathers against the train at 25.6 Hertz. This makes a rattling sound and causes the train feathers to vibrate at their natural resonance frequency ()
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Now they have turned their attention to female peafowl. While they are less visually spectacular than the males, peahens have spindly feathers on their heads, arranged in a characteristic fan shape.
Shaking that head
Kane’s team removed these crests from dead peahens and played sound recordings of train rattling at them. They found that the crests naturally resonate at 25.6 Hz – the average frequency produced by the peacock’s lustful train rattling. Control recordings of white noise did not trigger resonant vibrations.
This suggests that the crests on a peahen’s head would vibrate when a peacock rattled his train feathers. The peahen would probably feel the vibration, thanks to sensitive, hair-like feathers called “mechanosensitive filoplumes” at the base of their crests.
The researchers declined to comment on the study as it is currently under review at a peer-reviewed journal.
They do not have evidence to show the vibration encourages females to mate. To find out, they believe it might be necessary to blindfold live peahens and play them recordings of train rattling, to see if they respond to the vibrations alone.
Buzz buzz buzz
“This is very impressive,” says sensory biologist at the University of Lincoln in the UK. “It’s something that should be explored.”
Montealegre-Zapata wants to use a vibration-sensing device called a laser Doppler vibrometer to measure the crest feather resonance. “If I had one of the heads of these animals, I’d run the experiment right away,” he says. “That would be awesome.”
Finding an interaction like this in larger animals is exciting, says Montealegre-Zapata. The peahens’ sensitive crests are roughly analogous to certain insects, , says Montealegre-Zapata.
It is unclear when peacocks evolved the ability to generate resonance in a female’s crest. Other birds with elaborate feathers may have similar capabilities, and it is conceivable that some feathered dinosaurs could also do it.
bioRxiv
