The role of ultraviolet-A reflectance and ultraviolet-A induced fluorescence in the appearance of budgerigar plumage: insights from spectrofluorometry and reflectance spectrophotometry

Pearn, Sophie M., Bennett, Andrew T. D. and Cuthill, Innes C. 2003, The role of ultraviolet-A reflectance and ultraviolet-A induced fluorescence in the appearance of budgerigar plumage: insights from spectrofluorometry and reflectance spectrophotometry, Proceedings of the Royal Society of London series B-biological sciences, vol. 270, no. 1517, pp. 859-865.


Title The role of ultraviolet-A reflectance and ultraviolet-A induced fluorescence in the appearance of budgerigar plumage: insights from spectrofluorometry and reflectance spectrophotometry
Author(s) Pearn, Sophie M.
Bennett, Andrew T. D.
Cuthill, Innes C.
Journal name Proceedings of the Royal Society of London series B-biological sciences
Volume number 270
Issue number 1517
Start page 859
End page 865
Publisher The Royal Society Publishing
Place of publication London, England
Publication date 2003-04-22
ISSN 0962-8452
1471-2954
Keyword(s) parrot; budgerigar
spectrofluorometry
reflectance spectrophotometry
ultraviolet
fluorescence
Summary Fluorescence has so far been found in 52 parrot species when illuminated with ultraviolet-A (UVA) 'black' lamps, and two attempts have been made to determine whether such fluorescence plays any role in sexual signalling. However, the contribution of the reflectance versus fluorescence to the total radiance from feathers, even in the most studied species to date (budgerigars), is unclear. Nor has the plumage of this study species been systematically assessed to determine the distribution of fluorescent patches. We therefore used spectrofluorometry to determine which areas of budgerigars fluoresce and the excitation and emission spectra involved; this is the first time that such a technique has been applied to avian plumage. We found that both the yellow crown and (normally hidden) white downy chest feathers exhibit strong UVA-induced fluorescence, with peak emissions at 527 nm and 436 nm, respectively. Conversely, the bright-green chest and dark-blue tail feathers do not fluoresce. When comparing reflectance spectra (400700 nm) from the yellow crown using illuminants with a proportion of UVA comparable to daylight, and illuminants with all UVA removed, no measurable difference resulting from fluorescence was found. This suggests that under normal daylight the contribution of fluorescence to radiance is probably trivial. Furthermore, these spectra revealed that males had fluorescent crowns with substantially higher reflectance than those of females, in both the UV waveband and at longer wavelengths. Reflectance spectrophotometry was also performed on a number of live wild-type male budgerigars to investigate the chromatic contrast between the different plumage areas. This showed that many plumage regions are highly UV-reflective. Overall our results suggest that rapid surveys using UVA black lamps may overestimate the contribution of fluorescence to plumage coloration, and that any signalling role of fluorescence emissions, at least from the yellow crown of budgerigars, may not be as important as previously thought.
Language eng
Field of Research 059999 Environmental Sciences not elsewhere classified
HERDC Research category C1.1 Refereed article in a scholarly journal
Copyright notice ©2003, The Royal Society
Persistent URL http://hdl.handle.net/10536/DRO/DU:30022792

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