Carotenoids in bird plumage : the pattern in three Loxia species and in Pinicola Enucleator

We studied the carotenoid pigments in the plumage of Loxia curvirostra, Loxia polygina, Loxia leucoptera and Pinicola enucleator. The pigments were extracted under mild conditions and the extract analysed by high-performance liquid chromatography coupled with mass and ultraviolet-vis spectroscopy. In adult females and young males of Loxia, two major carotenoids, all-trans ε,ε-carotene-3,3'-dione and 3-hydroxy-ε,ε-carotene-3'-one, were responsible for the yellow colour of feathers. Minor amounts of lutein and 3'-dehydrolutein were detected. With sexual maturation, males turn red. The red colour of feathers was attributed to 3-hydroxyechinenone (3-hydroxy-β, β-caroten-4-one); small amounts of other orange-red carotenoids such as astaxanthin (3,3'-dihydroxy-β,β-carotene-4,4'-dione), adonirubin (3-hydroxy-β, β-carotene-4,4'-dione) and canthaxanthin (β,β-carotene-4,4'-dione) were also detected. Varying amounts of the yellow carotenoids found in females and young males were present. The same red pigments are observed in the adult males of P. enucleator. In contrast, in adult female and in young male pinicola, lutein and 3'-dehydrolutein were the major carotenoids. Two other carotenoids, not previously observed in bird plumage, were tentatively assigned to 3-hydroxy-β,ψ-caroten-4-one and 3-hydroxy-β,ψ-caroten-4-one (5'-cis).