Woodcocks are a whiter shade of pale
These waders sport the whitest feathers known to science – but they like to keep them under wraps
New research shows that the woodcock is the unlikely owner of the brightest white feathers of any bird tested so far. Woodcocks are not known for their dazzling colours. The upper plumage of these nocturnal waders is a mosaic of browns and greys that camouflages them exquisitely against forest floors by day.
“That’s the beauty of it,” says Jamie Dunning, who led the work at Imperial College London. “They keep it where you can’t see it, but where they can get it out when they need it.”
The research, published in the Journal of the Royal Society Interface, focused on a fringe of white spots on the underside of the tail feather tips of both sexes. The study revealed that these are 30 per cent brighter than any other plumage tested to date. The feathers’ barbs contain
microscopic reflective structures. They’re also flattened and overlapping, like Venetian blinds, to maximise the reflective surface area, and the angle at which they overlap reflects the light in a precise direction.
The feathers’ brightness probably aids visual communication in low-light environments, says Dunning. But what messages are they sending? And to whom?
Woodcock are well known for the males’ ‘roding’ flights performed for females on the ground. “We know females use [white feathers] to signal to males roding above them,” says Dunning. “And we think maybe the roding males use it too, because they fan their tail feathers as they do their parachuting flight down.
“We turned up an old, obscure reference to French hunters making fans out of the tail feathers and flashing them in the woods to attract woodcock,” he adds, “and another record of a female possibly flashing her tail feathers to a line of chicks following her.” The birds may also use it to startle predators. “If you catch woodcock in a net to ring them, they frantically flash their tail feathers at you as you approach,” says Dunning.
“It’s probably a bit of a multi-tool – and they can put it back in their bag when they’re finished with it.”