In the world of birds, if you’re a male looking for a lady friend, you’re going to have to put in some effort to woo her. This could involve growing ostentatious, brightly colored plumage, singing songs, dancing or even flower arranging for the choosy dame. But it’s not always the case that females sit there idle, watching the poor fella’s exhaustive attempts at seduction. Sometimes the females get involved, and now for the first time scientists have observed an elaborate “tap dance” display that both males and females perform during courtship.
The quick-footed feathered friends are called the blue-capped cordon-bleu (Uraeginthus cyanocephalus), a socially monogamous songbird that is one of just a handful of species in which the courtship displays are mutual, performed by both males and females. Although elaborate courtship rituals in males are thought to have evolved as a result of strong sexual selection pressure from females, there are exceptions in nature.
“In matchmaking parties, males choose females and females also choose males,” lead researcher Masayo Soma from Hokkaido University told IFLScience. “Even though human beings may not be monogamous in a strict sense, monogamous species tend to be mutually choosy, which can explain why in some species ornamentation or sexual signals exist in both sexes.”
For the blue-capped cordon-bleu, these mutual displays involve a bit of multitasking. They hold a piece of nesting material in their beaks while singing songs and bobbing up and down. But it turns out the action doesn’t actually end there. Researchers noted that rhythmical sounds were also being produced during the dance, but they didn’t know where these were coming from.
After observing the birds in the lab, one of Soma’s students noticed that the left and right feet might be making different movements, but the standard cameras they had been using weren’t fast enough to reveal any additional details. With a suspicion there may be more going on than meets the eye, the team recorded the birds during their rituals using a high-speed video camera.
After analyzing footage from 16 of the songbirds, the researchers discovered that both males and females rapidly tap their feet during courtship displays, step-dancing so quickly that it was invisible to the scientists’ eyes. For each bobbing motion, the bird would hop and stamp its feet repeatedly, which presumably produces vibrations responsible for the rhythmic sounds. They also found that if the birds were on the same perch, they would ramp up the dance and go full steam.
“Very slow tap dancing is also shown by blue-footed boobies, but I think our study is the first to discover incredibly rapid tap dancing in birds,” said Soma. “In this sense, cordon-blues are very unique.”
Not only that, but the production of non-vocal sounds is thought to be extremely rare in songbirds, given the fact these animals can tweet some impressively complex melodies. It seems that this unique combination of sound, visual and touch (vibration) signals allows the birds to communicate through several different means. These findings have been published in Scientific Reports.
As the researchers believe that the foot-tapping might be in synch with their songs, the team would like to further their investigation by looking into the coordination of these different courtship display facets, both in individuals and among partners.