Is the ultraviolet waveband a special communication channel in avian mate choice?

There is growing evidence that ultraviolet (UV) wavelengths play an importa nt role in avian mate choice. One of the first experiments to support this idea showed that female zebra finches (Taeniopygia guttata) prefer UV-refle cting males to males whose ultraviolet reflection has been removed. The eff ect was very strong despite little or no UV reflection from several plumage areas. However, it is not clear how the importance of the UV waveband comp ares to other regions of the bird-visible spectrum. We tested whether the r esponse of female zebra finches to the removal of male UV reflection is gre ater than to the removal of other wavebands. We presented females with a ch oice of males whose appearance was manipulated using coloured filters. The filters removed single blocks of the avian visible spectrum corresponding c losely to the spectral sensitivities of each of the zebra finch's single co ne classes. This resulted in males that effectively had no UV (UV-), no sho rt-wave (SW-), no medium-wave (MW-) or no long-wave (LW-) plumage reflectio n. Females preferred UV- and SW- males. LW- and MW- males were least prefer red, suggesting that female zebra finches show the greatest response to the removal of longer wavelengths. Quantal catches of the single cone types vi ewing body areas of the male zebra finch are presented for each treatment. Our study suggests it is important to consider the role of the UV waveband in avian mate choice in conjunction with the rest of the avian visible spec trum.