The Sexy Glow of Parrot Plumage

Top: The head of a Budgerigar (budgie) under white light. The fluorescence in the feathers cannot be seen. Bottom: The yellow fluorescence of a Budgerigar's head when viewed under short-wavelength illumination. These fluorescent markings make budgies more attractive to potential mates. © Science

Fluorescent colors in human fashion fall in and out of style, but the glowing look is always alluring if you're a parrot, according to scientists in the U.K. and Australia in the 4 January 2002 issue of the international journal, Science.

Kathryn E. Arnold of the University of Glasgow in Scotland and colleagues' ingenious experiment with budgerigar birds suggests that the budgies derive some of their sex appeal from the fluorescence of their feathers. Fluorescent pigments appear to "glow" when they absorb and re-emit UV light at longer wavelengths. The researchers tested for evidence of fluorescent sexual signaling in the birds by applying sunscreen to the bright yellow crown feathers of males and females, reducing the UV absorption of the plumage and consequently "dulling" their fluorescence.

The result: both male and female budgies show a significant sexual preference for brightly glowing companions, compared to their sunscreen-slicked rivals. This suggests that natural fluorescence may be an adaptive signal in the birds, rather than a simple byproduct of their feather coloring.

-- Becky Ham