The male bird of paradise Lawes' parotia creates his own disco atmosphere on the forest floor, displaying dramatic flashes of color using mirror ball-like structures that are described in a new Proceedings of the Royal Society B study.
The bird actually trumps dance club and fashion technology, since no known material -- engineered or biological -- has ever duplicated the brilliant hues and eye-catching color changes produced by this flashy avian dancer.
"We do not know of any man-made material that achieves the same effect," co-author Daniel Osorio told Discovery News.
Osorio and his colleagues came to that conclusion after examining the breastplate plumage of the bird using powerful microscopes and a device called the "scatterometer," which allowed the researchers to detect the complex optical properties of the feathers and how they reflect light in all directions at once.
"The parotia feather is unique in that each of the tiny barbules that are linked to make the feather blade is shaped so that it has two outer surfaces whose structure means that it reflects blue light in two different directions, while the interior of the feather contains a third mirror, made of multiple layers of keratin and melanin, which reflects yellow light between the two blue beams," Osorio said.
Male Lawes' parotia work the effect as he bobs, bows and dances performed for females during courtship display at chosen locations in the forests of southeast and eastern Papua New Guinea.
"Somewhat metallic colors can appear to almost gleam as they catch the light," Osorio said. "As the bird moves, they will switch between blue, yellow and black as the bird makes an elaborate sequence of dance steps on the forest floor or during displays on low branches."
On occasion, the male dancer will even erect his feathers so they face the sun, likely hoping to dazzle the female viewer with an extra burst of color.
The color is structural, Osorio explained, meaning that it doesn't result due to pigments, as is the case with human skin and paint products. It's more like the shimmering colors seen on soap bubbles and oil slicks. Peacocks, kingfishers and hummingbirds display iridescent feathers that are somewhat similar to those of the male parotia.
Surprisingly, perhaps the closest known match is found on the common feral pigeon. The pigeon's neck feathers shift from green to magenta, but often look drab gray to human eyes.
"In fact, this gray may be a remarkable and very unusual color to birds that can probably see more colors than us," Osorio said. "However, to our knowledge, the parotia has a unique, and probably the most effective, mechanism for making color switches."
He doubts that the eyes and color vision of the parotia are much different than those of other birds. The bird's forest home, however, might have led to the evolution of the avian flash dance.
"Forest-floor habitats provide very directional lighting that seems to favor mirror and jewel-like effects, not only on bird plumage, but also on butterflies and even fruit," he said.
John Endler, a professor of sensory and ecology evolution at Deakin University, told Discovery News that he "really enjoyed" reading the new paper, but he's "surprised (the structure of the male parotia feathers) has not been found earlier and in a variety of taxa."
"For example," he added, "it is well known that some hummingbird colors are only visible at the correct combination of viewer and sun angles, causing a flash of color during the display, and this is true of many structural colors."
In addition to hummingbirds, Endler suspects that certain butterflies, fish and other birds can achieve the multi-angled color mirror-ball effect of the male parotia. However, additional research is needed to confirm his suspicions that this has evolved in multiple species.
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