Natures wonders: tap dancing mating bird routine (Introduction)

by David Turell , Monday, September 19, 2016, 19:43 (2985 days ago) @ David Turell

A weird way to attract a mate:-https://www.newscientist.com/article/2106230-tap-dancing-songbirds-drum-with-their-feet-to-attract-mates/-"It is not just about speed. The only songbird known to perform a rapid tap dance during courtship makes more noise with its feet during its routines than at other times.-"The blue-capped cordon-bleu (Uraeginthus cyanocephalus) from East Africa is blessed with the attributes of a Broadway star: striking good looks, a strong singing voice - and fine tap-dancing skills.-"The dances are so fast that they went unnoticed until 2015, when Masayo Soma at Hokkaido University in Japan and her colleagues captured the performances on high-speed film. The bird's speciality is a left-right-left shuffle ­- only with the feet striking the perch up to 50 times a second.-"The vision of some birds operates at a faster rate than that of humans, so the cordon-bleu's dance may simply be about creating an impressive visual performance. But it could also be about winning over a potential mate with rhythm.-"To explore the idea, Soma and her colleagues recorded audio of the courtship dances, which both males and females perform.-"They found that the tap dances are unusually loud: the feet strike the branch with enough force to generate sound averaging 30 decibels. This typically drops to just 20 decibels when a bird's feet strike the branch as it hops around when it is not performing, which means the step sounds are not just a by-product of movement.
All this suggests that the sounds generated by the tap dances might be deliberate and an important signal for attracting a mate.-“'We have no doubt that their tap-dancing constitutes a very important part of courtship,” says Soma. But unravelling exactly how important will be difficult, she adds.-"Christopher Clark at the University of California, Riverside studies the non-verbal communications of animals, sometimes called “sonations”. He says the new study provides a reasonable case that cordon-bleus' tap dances belong in the sonation category. But he thinks more research could strengthen the idea.-“'The way they could improve the certainty that this behaviour is a sonation would be to do playback experiments,” he says. If cordon-bleus respond to the sounds of dances in the same way they do to the sound and motion of the dances, we can be confident that it is the rhythm of the dances that is most important to the birds.-"If cordon-bleus do join the sonation club, they will take their surprise place alongside other birds that use their wings, tails and bills to generate meaningful sounds. This club was thought to have evolved thanks to strong sexual selection on males that mate with several females - and so exclude monogamous songbirds such as these."-Comment: Stamp your foot to get attention? I don't understand what just-so story would explain why this instinct develops in evolution. Nothing demands this appear.