Owls use invisible pigment on their wings to send secret message

Recent research conducted by Drexel University’s College of Arts and Sciences has discovered an intriguing concealed feature in Long-eared Owls: their feathers have fluorescent pigments that shine under ultraviolet (UV) light, exposing a hidden spectrum undetectable by the human eye.

This finding, released in The Wilson Journal of Ornithology, implies that these luminous feathers may act as a hidden mode of communication among owls. Directed by PhD candidate Emily Griffith, the research examined feathers gathered from 99 Long-eared Owls migrating through Michigan’s Upper Peninsula in the spring of 2020.

The team utilized a fluorometer, an instrument that gauges fluorescence, to identify different levels of fluorescent pigments—mainly porphyrins—in the inner wing feathers of the owls.

These pigments produce a vivid pink luminescence when exposed to UV light, detectable by owl eyes naturally, whereas humans need artificial UV light. Notably, the fluorescence is stronger in females and older birds, which contradicts the typical belief that bright feathers are solely a male characteristic for attracting mates. Rather, the concentration of pigment varies on a spectrum affected by age, gender, and size.

The researchers suggest that the glow could serve purposes beyond attracting mates, potentially helping with temperature regulation during incubation, as females, which incubate eggs, show increased pigment levels.

The covert aspect of this fluorescence might enable owls to communicate with one another while keeping their prey, like rodents, unaware, as these animals are unable to perceive UV light.

Throughout courtship, males execute flights that may showcase these luminous feathers, likely communicating details regarding health or vitality. Nevertheless, the precise aim is still unclear, and the investigators stress that comprehending these “concealed” characteristics necessitates additional research. The radiant plumage of Long-eared Owls introduces a fresh aspect to bird biology, indicating that nature’s methods of communication reach well beyond our ability to detect.