Description:
<p>Birds frequently display a colourful plumage which is important both in inter and intraespecific communication, and either in sexual and social contexts. In last years some methodologies have been developed to analyse plumage coloration, but the use of the spectrometers has been particularly important for UV range. Measurement of plumage coloration with the spectrometer may be taken directly on the bird or, alternatively by collecting some feathers and measuring them later in the laboratory. However, few is known about the reliability of measures obtained from feathers and whether these are really representative of plumage coloration. We tested this assumption analysing measurements of carotenoids-based coloration components (lightness, chroma and hue) and lutein peak of the yellow breast of the great tit Parus major We used two spectrometers (Ocean optics and Minolta) which calculate differently the colour components. Our results showed that direct measurement of bird was highly repeatable to determine lightness, chroma and hue for both spectrometers. Similar results we found for collected feathers procedure for both devices. Collected feathers provided high representative measurements of colour values with Minolta spectrometer. Lightness was highly repeatable when we used Ocean optic spectrometer, but chroma and hue were moderate. Lutein peak was also highly repeatable in all cases. The number of feathers used to measure plumage coloration in collected feathers procedure strongly influenced values of colour plumage variables. In general, values of lightness, chroma and hue stabilised when more than 10-15 feathers were used although we found slight differences between spectrometers. However, only four feathers were needed for lutein peak. Thus, our results stress the need to use a minimum number of feathers in measuring plumage coloration from collected feathers.</p>