Elaborate poses, tufts of feathers and ornate shuffles shuffle along the Immaculate Forest Floor. Male birds have many ways to plead for potential companions.
But now, by examining specimens prepared at the American Museum of Natural History in New York, scientists have discovered that it is yet another tool in the tropical bird kit.
This phenomenon, sometimes called biological fluorescence, occurs when an object absorbs high energy wavelengths and re-emits them as lower energy wavelengths.
Biofluorescence has been discovered in a wide variety of fish, amphibians and even mammals, from bats to wombats.
Interestingly, birds remain grossly understood when it comes to optical extras. Until now, we have not been looking for the sparkling property of the paradise birds native to Australia, Indonesia and New Guinea and famous for their elaborate mating displays.
In a study published Tuesday in the Journal Royal Society Open Science, researchers looked at preparatory specimens housed at the American Museum of Natural History and found evidence of biofluorescence in 37 of the 45 paradise species.
“What they're doing is not able to see this UV ray, they can't see it, and actually re-radiate it at the wavelengths they can't see,” said the research's lead author. said biologist Rene Martin. University of Nebraska, Lincoln University. “In their case, it's kind of a bright green and a green yellow colour.”
In short, biological fluorescence enhances bright colors and brightens them.
Of all the avian paradise species, three genera (Cicinnurs, Seleucidis, and Semioptera) showed no evidence of biological fluorescence.
Dr. Martin said this could be because these birds tend to be much more monogamous. This means there is less need for elaborate display and competition between men.
The most likely scenario is that all of these animals produce biological fluorescence, as researchers have also discovered blue cap IFRIT, which is thought to be the only sister species of paradise birds. It was derived from a common ancestor that gave them. marking. The three genera that no longer possesses it must have lost their traits somewhere along the way.
Previous studies have found that many species of bird paradise have evolved different colour habits.
Scientists have discovered that many of these ornate birds appear to have some of the biological fluorescence near or framed Ultrablack. This juxtaposition could enhance the entire display. This may show women that performers have excellent breeding quality.
Females from many bird paradise species also exhibited biological fluorescent feathers, but Dr. Martin said the female pattern was much more calm. Most women of these species are those who make choices, reinforcing the idea that men shine for sexual choices.
Male birds may also display colours as a way to establish a hierarchy. In other species, such as snakes, scientists believe that biological fluorescence functions as a way to blend with bright forest backgrounds. Therefore, the next level of colour is very likely to be useful for multiple roles.
It may seem clear that biological fluorescence evolves many different eras in animal kingdoms for purposes, but scientists warn against the assumptions. After all, human teeth fluoresce under ultraviolet rays, but it doesn't seem to help us in a measurable way. Some may argue that shining teeth are a disadvantage.
To prove its function, scientists turn to a set of five criteria. This list can be used to see whether the animal's habitat has a naturally available level of light wavelengths known to be absorbed, or the wavelength at which the animal's eyes are re-radiated. It includes whether it is highly sexual or not.
“It appears that bird paradise encounters four of the five criteria for visual function,” said Linda Reinhold, a zoologist at James Cook University in Australia.
However, Reinhold said that the fifth criterion for assessing whether animal behavior changes as a result of biological fluorescence has not been tested for bird birds. Of course, trying to observe clumsy birds in remote habitats filled with uncontrolled variables might mean that this particular test won't be resolved anytime soon.
Studying birds in person will have other benefits.
“These birds in their natural habitat will be even more fluorescent than museums,” Reinhold said.
