Green head tagers (Tangara celery) are surprisingly colored
Daniel Field
The bright -colored singing birds called tagers are so catchy because they have a layer hidden of black or white under their dazzling plumage.
The painters often damage a canvas with a layer of white to improve the colors on which they will end up superimposing, as well as to make it smoother and stronger. But it seems that it was a mechanism that birds used long before humans picked up brushes.
Rosalyn Price-Waldman at Princeton University and his colleagues discovered that when singing birds in the genre Tankara Have a bright or yellow red plumage, they usually have white -hidden layers below. When they have a blue plumage, they have black layers below.
To investigate why, they deleted 72 feathers of Tadiage Tader specimens to the Los Angeles County collection.
By taking photos of the feathers on different backgrounds, the team has measured how their reflectance or their absorption of light has changed, noting that the undercoators make the upper layers more colorful.
The red and yellow coloring is created by pigments, which are molecules which selectively absorb the light to make the color. This means that the retradifying light of the white below makes them brighter, explains Price-Waldman.
But blue coloring is created by nanostructures in the feathers that selectively disperse light, rather than absorbing light to create the color we see. For this reason, the black absorbing the light below makes the blue brilliant. “If you have white below them, they seem white gray color,” explains Price-Waldman.
The global effect of plumage is created because the feathers are in layers like tiles on a roof, she says. When you take a single pen, it can have a colorful point, an intermediate region of black or white, then the fluffy and fluffy base. When these feathers are superimposed on the body, the tips create a contiguous layer of color, above a contiguous layer of white or black.
Blue feathers on the crown of a Red neck hoist (Tangara cyanocephala) are intensified by a layer of black plumage below
Rosalyn Price-Waldman, Allison Shultz
Price-Waldman and his colleagues also found that, in some cases, these layers of feathers generate the differences in color between the sexes.
“We found some cases where the females had black under yellow and the males had a white under yellow,” she said. “When you put their feathers on the same background, the feathers are really similar. It is only when you take the male feathers and put them in white and the female feathers on a black background that you really get the big differences in coloring you see.”
Researchers have found that this color stimulation strategy is observed in many other singing birds, including Manakins and Cotingas.
“Although many research has already been done to understand how birds produce such striking colors, there is clearly a lot to discover,” explains Chris Cooney at the University of Sheffield, in the United Kingdom. “It seems that this” hidden “mechanism to improve the brightness of plumage colors can actually be quite common between bird species.”
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