Did birds trade off colours for song

New York, Are animals limited, as proposed by Darwin, in their options to evolve showiness? No, says a new study done on one of the world's largest and most colourful bird families.

The widely held belief is that birds' bright colours, big crests and tails and intricate dance routines or melodious singing are the result of trade-offs.

That is, for a species to excel in one area, it must give up its edge in another.

"Animals have limited resources, and they have to spend those in order to develop showy plumage or precision singing that help them attract mates and defend territories," said lead author Nick Mason.

"So it seems to make sense that you can't have both. But our study took a more detailed look and suggests that actually, some species can."

Mason and his colleagues tested the idea of trade-offs by looking at a very large family of songbirds from Central and South America, the tanagers.

This group consists of 371 species - nearly 10 percent of all songbirds. It includes some of the most spectacularly colourful birds in the world such as the Paradise Tanager as well as more drab birds such the Black-bellied seedeater.

"If there were going to be any group of birds at all that would show this trade-off, the tanagers would be a very good candidate, because there's all this variation in song and plumage complexity," Mason said.

"But when we dive into it and do some rigorous statistics, it turns out that there is no overall trend.

"Tanagers can be drab and plain-sounding, or colorful and musical, or anything in between," he explained.

The study puts a significant dent in the idea of evolutionary trade-offs between plumage and song.

"It's still possible that trade-offs take place at the level of genus. But as a broad effect on an entire family of birds, a voice-plumage trade-off doesn't seem to exist," he concluded.

The study was published in the Proceedings of the Royal Society B.

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