Camouflage feathers send sexy signals

By Julian Swallow with AAP 21 September 2010
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Birds with less fancy feathers use their patterns for both attracting mates and camouflaging, new research says.

BRIGHT FEATHERS AND FANCY plumage are thought to be an advantage for birds attracting mates, but new research suggests that plain janes can be just as successful at the mating game.

Barred patterned feathers, like the alternate horizontal dark and light colours found on hundreds of bird species including zebra finches and cuckoos, apparently play a role in attracting mates and fending off rivals, according to a University of Melbourne study.

Unlike bright and colourful feathers, barred patterns were previously thought to be used only for camouflage. But, says lead researcher Thanh-Lan Gluckman, the study has found they can also be a boon for attracting mates.

“Feathers don’t need to be bright and showy to be used in sexual signalling and, hence, this changes our understanding of animal communication,” she says.

“Elegant evolutionary solution”

The study examined male, female and juvenile bird plumage from 90 per cent of the world’s known bird species to compare plumage patterns, and found that in species which barred plumage occurs, it is most likely to appear on males after they reach sexual maturity – suggesting its use as a tool for sexual communication.

Moreover, these patterns occur on the front of the bird, an area that plays an important role in their interaction with others. The standard camouflage patterns found mostly on the back, however, assist in escaping detection from predators.  

Thanh-Lan says the patterns show how bird markings can accommodate the seemingly incompatible functions of camouflage and communication, and has implications for our understanding of bird sexual ornamentation.

“This is an exciting finding showing an elegant evolutionary solution to the needs of birds to camouflage as well as to signal to a potential mate,” she says.

Professor Gisela Kaplan an expert in animal behaviour from the University of New England, Armidale, believes the findings could prove to be extremely important. She says Thanh-Lan’s study has shown “that the same plumage pattern when in front may have a different function than when found on the back and this is a very innovative idea.”

The study is published in the Journal of Evolutionary Biology.