Fluorescence and sexual dichromatism in the Blue-winged Parrotlet

BARREIRA, ANA S.; LAGORIO, MARÍA GABRIELA; LIJTMAER, DARÍO A.; LOUGHEED, STEPHEN C.; TUBARO, PABLO L.

Portland, Oregon, USA

Congreso; AOU/COS/SCO PDX 2008 MEETING; 2008

American Ornithologists' Union, Cooper Ornithological Society, Society of Canadian Ornithologists

Birds are known to be able to perceive both visible and UV wavelength radiation. Therefore, objective studies of spectral reflectance independent of human perception became popular to approach sexual dichromatism. However, fluorescence properties of feathers have been much less studied. Fluorescence occurs when short wavelength radiation is absorbed and re-emitted as longer wavelength radiation. We studied the plumage coloration of the Blue-Winged Parrotlet (<em>Forpus xanthopterygius</em>), describing its reflectance and fluorescence properties and found sexual differences in both. Maximum fluorescence emission was obtained when the plumage was excited with UV wavelengths, and its intensity was higher in the visible range, close to the wavelengths of maximum total reflectance. Intensity of fluorescence was higher for males than for females. The shapes of total reflectance and reflectance without the fluorescent component differed significantly, and the presumption that this difference is due to the influence of fluorescence is supported by the shape of the fluorescence spectrum. These results suggest that the fluorescent component is significant to total color signal and might act as an enhancer of sexual dichromatism in this species.