Reflectance Spectra of Plumage Areas Colored by Green Feather Pigments

-Only rarely are green plumage colors due to the presence of green pigments. The best known is turacoverdin. Two galliform species (Ithaginis, Rollolus), Jacana and some anseriform species (Somateria, Nettapus) also have green pigments. The reflectance spectra of plumage pigmented by turacoverdin are characterized by distinct minima at about 570 and 610 nm. These minima represent absorption bands as confirmed by a transmittance spectrum of a turacoverdin extract. Surprisingly, the spectra of the two galliform species and Jacana also exhibit the characteristics of the turacoverdin spectrum, while that of Somateria is different. I show that the pigments of Ithaginis, Rollolus, and Jacana also resemble turacoverdin in containing copper in relatively high concentration, and conclude that these pigments are identical with or closely related to turacoverdin. Intraand interspecific variation in reflectance spectra is assumed to be largely determined by the presence of dark, nongreen pigments in the plumage. The spectrum of turacoverdin supports the hypothesis that the pigment is closely related to the well-known red pigment of turacos (Musophagidae)-turacin. However, the chemical constitution of turacoverdin remains unknown. The presence of turacoverdin and turacin in the plumage of the Musophagidae hitherto has been considered an autapomorphy of the turacos. The fact the turacoverdin also is present in two possibly related galliform taxa argues for phylogenetic relationships between the Musophagidae and the Galliformes. Received 3 April 1991, accepted 10 January 1992. GREEN, noniridescent plumage colors can be produced in a number of ways (Auber 1957). The combination of a structural blue color with yellow pigments, as found in parrots, is best known (Frank 1939, Dyck 1971). The olive-green colors obtained by the juxtaposition of yellow and blackish pigments (apposition colors; Auber 1957, Dyck 1978) also are widespread. Central to my two studies is the question of the evolution of plumage colors that resemble the green colors of leaves, without chlorophyll being available as a feather pigment (Needham 1974:81). In principle, the simplest way to produce a green plumage color is to deposit a green pigment within the feather keratin. This possibility has been realized in only a limited number of cases. The best-known green feather pigment is turacoverdin. This is found in some turacos (Musophagidae), especially the species of Tauraco and Musophaga, and possibly also in the Great Blue Turaco (Corythaeola cristata; Krukenberg 1882, Moreau 1958). Preliminary chemical studies have been carried out (Moreau 1958). Other known green pigments are zooprasinin in the remiges of the Jacana (Jacana spinosa, Jacanidae; Rensch 1925), phasianoverdin in belly feathers of the Blood Pheasant (Ithaginis cruentus, Phasianidae; Gotz 1925), and a green pigment in much of the plumage of the Roulroul (Crested Wood-Partridge, Rollolus roulroul, Phasianidae), especially the female (Volker 1961). The green pigments in some anseriform species (Nettapus, Somateria; Auber 1957) are poorly known (Brush 1978). I describe the reflectance spectra of green plumage areas in several species and discuss factors that influence the shapes of the spectra. I compare the reflectance spectra with the spectrum of turacoverdin in extract and from this infer the probable identity of some of the pigments. MATERIALS AND METHODS Most measurements were performed on study skins from the Zoological Museum, University of Copenhagen, and the British Museum (Natural History). A few measurements were also carried out on mounted specimens. The spectrum of the nape of an adult male Eider (Somateria mollissima) was scanned on feathers taken from a newly dead bird. Feathers plucked from live birds were obtained from the Zoological Garden, Copenhagen, and kept four months in the dark before measurement. Reflectance spectra were obtained on a Beckman DK-2A spectrophotometer with a reflectance attachment and using a reference of magnesium oxide. The illuminated spot was approximately 8 x 8 mm.