Australia’s indigenous crested pigeon (Ochyphaps lophotes) is in the scientific spotlight – because it has developed the ability to ‘whistle’ with its feathers.
According to a recent report in Current Biology the bird is able to signal alarm with specifically modified wing feathers.
Researchers used video and feather-removal experiments to demonstrate that the highly modified 8th primary wing feather (P8) produces a distinct note during each downstroke.
When crested pigeons flap their wings to take off, the upstroke of each beat produces a 1.3-kilohertz low note, and the downstroke produces a 2.9-kilohertz high note.
The study group found that the noise came from the eighth feather on the pigeon’s wing – and the high note disappeared when that feather was removed. But when the feather was placed in a wind tunnel, the high-frequency sound returned.
To see how other birds reacted to the noise, the researchers played audio recordings of slow and fast wing beats to pigeons in their natural habitat.
During the slow beats, the birds stayed where they were. But the faster wing beats set the birds fleeing. It seems these ‘wing whistles’ are serving as a type of warning signal – based on the speed of the cycle.