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Many types of birds – such as hummingbirds, peacocks and parrots – are colored, but Birds of paradise are particularly flamboyant with colors of emerald, lemon, cobalt and ruby. Now research has revealed that these superb birds also send signals of secret colors invisible to human eyes.
Plumage and body parts of the birds of paradise shine in certain areas when they are seen under blue and ultraviolet, or UV, light, appearing bright green or yellow-green, said scientists in a new study published on February 12 in the review Royal Society of Open Sciences.
Living organisms produce light in two ways: bioluminescence and biofluorescence. Bioluminescence (The light produced by fireflies, for example) requires a chemical reaction involving Luciferin and Lucifrase molecules. Biofluorescent creatures generate their glow with structures that absorb high -energy wavelengths with light, such as UV, purple or blue, then emit light in a lower energy wavelength.
The researchers described biofluorescence in 37 of the 45 known species of birds of paradise, Found only in distant tropical forests and wooded habitats of Papua New Guinea, eastern Indonesia and parts of Australia. Enlightened by blue and UV light, the white and bright yellow plumage of birds diffuse colors that can be used in territorial disputes or to find partners, depending on the study.
Birds are known for their exceptional vision of colors, and many types of birds – Among them pigeons, turkeys, ducks and geese – can see in the UV spectrum. We know little about the vision of birds of paradise. However, some closely related lines, including the genus Corvus (Crows and Ravens), the genus Rhichidura (Fantils) and the Pica genre (a type of magpie) are known to have a sensitive vision to Wave lengths of purple light. For such birds, fluorescent brands would shine like a beacon in darkness, the authors of the study wrote.
“The study is well designed, in terms of gaze through the diversity of the group of birds of paradise as well as of some of their close relatives,” said Dr. Jennifer Lamb, associate professor of biology at St. Cloud State University of the Minnesota. LAMB, which studies biofluorescence in amphibians and reptiles, was not involved in research.
“What is really interesting about biofluorescence is that even if it is a visual signal, or it can be a visual signal, it has always been relatively sub-studied in many different groups “Said Lamb. “We have therefore ignored this potential field of visual signaling and visual communication, mainly because it is not something that our own eyes perceive.”
Although birds of paradise are known for their dramatic colors, the biofluorescent aspect of their visual communication was not previously described and raises new questions about how birds use visual clues, said Dr. Rene Martin, author of the main study.
“This is just an additional piece to the puzzle,” she told CNN. “And if it can be found in a group that is probably very well studied, you can find things like this anywhere.”
More than a decade ago, the author of the main study, Dr. John Sparks, Curator of the Ichtyology Department of the American Museum of Natural History, or AMNH, in New York, Biofluorescence identified through many species of fish. This observation led him to wonder what extent this trait was widespread through other animals, said Martin, a colleague biologist of fish and assistant professor at the University of Nebraska – Lincoln.
Sparks could access a wide range of bird specimens in AMNH. A preliminary scan through the museum’s ornithology collection with blue light confirmed its suspicions, revealing fluorescent traces in the birds of paradise, said Martin. But it was only when Martin joined the museum in 2023 as a postdoctoral researcher that the investigation went further.
With sparks and studies, the co-author Emily Carr, a doctoral student at the Richard Gilder School of the museum, Martin revisited the specimens of the birds of paradise in the drawers of Amnh.
“I essentially took blue pocket lamps and high-power UV pocket lamps and I traveled the collection,” she said. While she was looking for, she wore special glasses that blocked blue light and only revealed the lighting produced by birds of fluores.
The scientists then took these birds to a room without light where they photographed them and measured light broadcasts. Depending on the species, fluorescence presented in different parts of the body, such as the belly, the chests, the heads and the cous of the birds. Some species had long shiny plumes, shiny invoices or sparkling spots in their mouths.
“Often, fluorescent areas were lined with very dark pigmented feathers, which were contrasting with this fluorescence,” said Martin. “Many of these birds of paradise have also evolved something called an ultra -black pen that sucks a lot of this light – which is interesting, because the group of birds of paradise which are not biofluorescents don ‘t this pen Ultra-Noire. »»
There are more than 11,000 known bird speciesBut only a handful of groups are known to fluorescence. Other researchers previously described biofluorescence in auks, bumps, owls, nocturnal, parrots, penguins and puffs, but we know little about how they use biofluorescent signals, reported the study authors.
“In parrots and in the birds of paradise, it is assumed likely that they use it in a kind of communication or reproductive demonstrations,” said Martin.
But in some of the other groups in which biofluorescence has been found, scientists do not know what it is used, “or if it is even used for something,” added Martin. “It could be something that has evolved as a protein useful for being a good structure in a pen, which just comes to biofluorescences.”
