Birds of a Feather 

Birds are among the most colorful creatures in the world – exclusively black or white avians are rare.  

Now, a new study is showing a trick used by birds to make themselves even more colorful. 

The study focused on a species of tanager – very colorful birds native to Central and South America – and found that the black and white feathers are crucial in making birds’ colors more vivid.  

In other words, when colored feathers are put on top of a layer of either black or white feathers, their colors get a boost. 

“When painters are priming their canvases with gesso – with white gesso, that’s exactly the same physical phenomenon,” study author Rosalyn M. Price-Waldman told NPR. “It’s increasing light-scattering from the canvas in order to make the pigments on top look brighter.” 

A particularly surprising finding of the study was that in some species, the color difference between males and females isn’t caused by the pigments in the feathers but by variations in the amount of black or white in the underlying feather layers, explained Simon Griffith, a professor of Avian Behavioral Ecology at Macquarie University in Australia, writing in the Conversation. 

Usually, male birds present more vivid colors than females. 

Charles Darwin already knew that more colorful males tend to attract more mates and produce more offspring than their duller rivals. 

Showcasing vivid colors, therefore, has been key to survival.  

Having a layer of black underneath patches of bright blue feathers allowed male birds to produce an extra vibrancy that proved crucial in the competition for mates. This is because the feather structure scatters light to create the blue hue, while the dark under-layer absorbs other wavelengths, making the blue stand out more intensely. 

Meanwhile, yellow feathers are enhanced by a white under-layer, which reflects the light that passes through the feathers, increasing the brightness of the yellow patches and making them more striking in contrast to surrounding patches of color. 

After studying tanagers, researchers considered whether the same mechanism happened in other birds as well and found that a lower layer of black and white feathers enhances colors in many other species. 

“This widespread use of black and white across so many different species suggests birds have been enhancing the production of color in this clever way for tens of millions of years, and that it is widely used across birds,” Griffith added.