Good vibrations for peafowl described in Science (AAAS) News, and ScienceDaily 28 November and PLoS ONE 28 November 2018 doi: 10.1371/journal.pone.0207247.
When peacocks display their splendid iridescent tail feathers (called trains) to a peahen they also shake them – a behaviour known as train rattling. As well as making an audible rattling sound, this behaviour also produces very low pitched vibrations that are inaudible to humans. Peacocks also perform a wing shaking display during courtship. Scientists have previously found that peahens respond to these sounds and movements even if they cannot see the peacock.
A group of biologists and physicists have studied the crest of feathers that both sexes have on top of their heads to see if it was the means of detecting the sounds. This crest consists of upright feathers neatly aligned like a row of small flags. The scientists found the base of the crest also had fine feathers named filoplumes, which are known in other birds to respond to vibrations and also act as mechanosensors (sensors that respond to touch and movement). They then tested the crest feathers to recordings of the train rattling display other sounds, and to a simulated wing shaking display, and found that the crest feathers vibrated at the frequency of the low pitched sounds produced by the train rattling behaviour and to the airflow produced by the wing shaking. The crest feathers did not respond to random white noise.
This led the scientists to conclude “These results demonstrate that peafowl crests have mechanical properties that allow them to respond to airborne stimuli at the frequencies typical of this species’ social displays.”
They suggest that peafowl and other bird species may use this kind of vibration signalling as a way of complementing visual displays. They wrote: “We suggest behavioral studies to explore these ideas and their functional implications.”
Editorial Comment: This study is a good reminder that communication requires two functioning systems to be at work at once. Both the signal producer and the receiver must be present, and there must be understanding of what the message means one both sides. After all, it is no use for the peacocks to produce the right frequency vibrations with their trains and wings unless the peahens’ head crests are already structured to respond to the vibrations, and are connected to the birds’ brains, which has to interpret them correctly.
Such a multiply interactive system requires forward planning to make the structures needed at the same time, and information to be implanted in both participants. These are the characteristics of creative design, not of chance random evolution.
Finally, if you think it is over-engineering for peacocks to have a spectacular visual signal as well as a clever sound signal, remember that peahens are not the only living things that see peacocks. People see them as well, and enjoy their beauty. God loves beauty, and has made things that are both beautiful and functional for us to enjoy and study, and give our Creator thanks and praise for making things that are both beautiful and functional.
Evidence New vol. 18 No. 18
12 December 2018
Creation Research Australia
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