Birds-of-paradise are celebrated for their vibrant and colorful feathers, but recent research reveals they possess an even greater allure than previously recognized.

A team of researchers has discovered that 37 out of 45 birds-of-paradise species exhibit biofluorescence. This fascinating phenomenon means certain areas of their plumage, or other body parts, can absorb UV or blue light and subsequently emit light at lower frequencies.

“At the very least, these biofluorescent zones would enhance brightness—so while a yellow feather may appear more green-yellow, a white feather could become radiantly brighter and take on a slightly green-yellow hue,” explained Dr. Rene Martin from the American Museum of Natural History in New York, who led the study.

The findings, published in the journal Royal Society Open Science, detail how the researchers analyzed preserved specimens of each bird-of-paradise species housed in the ornithology collection at the American Museum of Natural History.

The research team examined both male and female specimens under blue light in a darkened environment, measuring the emitted light’s wavelengths and intensity. They also tested some skins with UV light.

Their results highlighted that males from 21 species exhibited biofluorescence in various plumage areas, including the head, neck, belly, and tail feathers, in addition to fleshy features known as face wattles. Furthermore, these species, alongside an additional 16, were also likely to display biofluorescence in their inner mouth and throat areas.

Females from 36 of these species, and likely all 37, also showcased biofluorescence, prominently on their chests and bellies or in eye stripes on the sides of their heads.

The emitted light was found to range from light teal blue wavelengths to shades of green and green-yellow.

“While this phenomenon may not drastically change the appearance of the feathers, it definitely enhances brightness and visual appeal,” said Martin.

Interestingly, biofluorescence was absent in species belonging to the genera Lycocorax, Manucodia, and Phonygammus, supporting the theory that biofluorescence originated in the common ancestor of all birds-of-paradise but was lost in the lineage of these three groups.

The researchers suggested that the intricate courtship displays of many biofluorescent species would be amplified by this effect. For example, male Lophorina birds open their mouths towards females during their performances.

“Male birds-of-paradise often feature bright patches next to dark plumage, so the biofluorescent effect may enhance the visibility of these areas during displays,” added Martin.

Conversely, for females, the impact of biofluorescence may serve a different purpose. “The placement and patterns of biofluorescent feathers in many species might be more aligned with camouflage functions,” she noted.

Martin emphasized that this research provides new insights into the well-studied birds. “Even a charismatic group like the birds-of-paradise continues to offer valuable information regarding avian vision, behavior, and physical characteristics,” she concluded.