Tropical boubou couple performing a duet: "Monogamous birds knowing they are the champions."

© Johannes Bitz / afrol News

afrol News, 9 March - To most listeners, the tropical boubou is just singing. Research in the dense thickets of Côte d'Ivoire however reveals that this African bird has a large song repertoire - each with a single meaning. The repertoire also includes 12 duets that the male and the female sing together, one of which can be equalled to the "We are the champions" sports song.

Winning a fight against intruders of the same species appears to put the tropical boubou - an all-African bird - in the mood for a very special song. Research published in 'BMC Ecology' describes a rare example of a context-specific birdsong and identifies the tropical boubou as the first bird species known to sing a 'victory duet'.

The birds probably sing to deter other birds from intruding into their territory. According to the authors, "we were able to hear the male note of the victory display across two territories, further than notes of other duets. Also, it was typically sung from higher perches than other duets, making it more conspicuous."

Tropical boubous are monogamous birds. The male and female of a pair often sing duets, with each bird having a distinct part. The species occurs throughout sub-Saharan Africa, mostly favouring dense thickets in wooded areas and forest edges.

German researchers Ulmar Grafe and Johannes Bitz visited the Comoé National Park in Côte d'Ivoire to find out how tropical boubous respond to their territory being invaded. The researchers broadcasted recordings of four duets, which are often sung during contests over territory, to 18 different pairs of birds.

Sixteen of the tropical boubou pairs stood their ground, and 11 of these pairs sung the 'victory duet' within 30 minutes of the researchers turning off their tape machine. The birds that flew off - presumably after 'losing' the battle - didn't sing any note at all for at least 30 minutes.

The 'victory duet' was the first and only song that the birds sung within 30 minutes of the antagonistic encounter. The tropical boubous waited for at least 150 seconds of silence, to check that the invaders had gone, before they announced they were the winners.

- Analysis revealed that the presumptive victory display was sung significantly more often after than before or during playback of recordings, write Mr Grafe and Mr Bitz. Like other duets sung by male and female tropical boubous, the 'victory duet' contained "highly synchronised tonal notes that were often repeated." However this song was longer than the other 12 songs in the tropical boubous' repertoire, with the same motif being sung around 40 times on average.

Mr Grafe, a zoologist at the University of Würzburg, told afrol News that duetting is known to occur in about 3 percent of all bird species worldwide or approximately 222 species. With few exceptions it occurs only in tropical species. The tropical boubou has a repertoire of 12 duets, and the 'victory duet' was found to be unique to the tropical boubous.

- This is a rare example of the use of a song type in one very specific context, Mr Grafe explained. "There are also not very many examples of displays used to signal victory in animals," he added. This made the documentation of the 'victory duet' such a unique research result, according to the German scientists.

By staff writer

© afrol News

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