Good looks and singing aren’t a trade-off for birds
Washington: Beautiful plumage and complex songs are not mutually exclusive, according to a study of one of the world’s largest and most colourful bird families that overturns a theory, first proposed by Charles Darwin, that birds are limited in their ways of showing off.
The natural world is full of showstoppers – birds with brilliant colours, exaggerated crests and tails, intricate dance routines, or virtuosic singing, researchers said.
But it has long been thought that these abilities are the result of trade-offs. For a species to excel in one area, it must give up its edge in another, they said.
For example, male Northern Cardinals are a dazzling scarlet but sing a fairly simple whistle, whereas the dull brown House Wren sings one of the most complicated songs in nature.
“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 Nick Mason, a PhD student at the Cornell University and the paper’s lead author.
“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,” said Mason who did the research as a master’s student at San Diego State University.
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 per cent 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. The group also includes both accomplished and weak songsters alike.
“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, noting that the group’s large size lends confidence to the statistical analysis.
“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 colourful and musical, or anything in between,” said Mason.
The study appears in the journal Proceedings of the Royal Society B.