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Melbourne, Sep 2 (ANI): An Australian species of pigeon, called the Ocyphaps lophotes, has the ability to produce a unique whistling sound with its wings to alarm others in the flock about any potential danger, say researchers at the Australian National University in Canberra.

Behavioural ecologist Dr. Robert Magrath and student Mae Hingee have discovered how one bird in a large group spots a predator, and communicates it to the rest.

While some bird species use vocal alarms as a warning, Australian crested pigeon, Ocyphaps lophotes has a very curious whistling sound when it flies, which seems to change when it flies off in alarm, says Magrath.

“You can close your eyes and know when a crested pigeon is flying around,” ABC Science quoted him as saying.

Magrath said that the whistling sound is so loud that some birds might suspect that it was made vocally, but it is actually made by the pigeons’ wings.

“In fact one of their common names is the whistle-winged pigeon,” he said.

To test their hypothesis that the crested pigeon might be using its whistling feathers as an alarm, the researchers created model hawks to scare flocks of crested pigeons.

They recorded the whistling sound made by pigeons taking off in alarm and compared this to a recording of the whistling sound made by birds taking off routinely.

Then, the researchers analysed the characteristics of the different wing whistles on computer, and found that each downbeat and upbeat of the wings produced different tones but the alarm signal was faster and louder than the routine flight sound.

In the next step, they independently tested whether the birds responded differently to the two different sounds.

They recorded the alarm and routine flight sounds onto CD and then played them back to flocks of birds.

“If you played back the routine whistle they just kept on feeding as if nothing had happened. If you played back the alarm whistle they just shot off - 80% of the flocks just went for the hills. Clearly the birds are playing attention to these whistles,” said Magrath.

Magrath has said that there is a special feather on the wings that appears to be key to the whistles and it amplifies the differences between slow and fast wing flapping, turning a routine whistle into an alarm whistle.

The scientists have published their findings in the Proceedings of the Royal Society B. (ANI)