Pigments and Feather Structure of the Redpolls, Carduelis flammea and C. hornemanni

Abstract

Spectral profiles of intact carotenoid-bearing feathers and of pigments isolated from polls and breasts of Common and Hoary redpolls (Carduelis flammea and C. hornemanni) were compared to help clarify the taxonomic relationship of the two taxa. Pigments were identified by thin-layer chromatography and by partitioning experiments. Two carotenoids were present in all samples, apparently echinenone and lutein. Color differences between taxa result from differences in absolute concentrations and changes in the relative concentration of the two pigments. Orange feathers have relatively high concentrations of lutein. Pigments are restricted to feather rami. Those most intensely colored (from polls) have flattened rami and lack barbules. New breast feathers are tipped with an unpigmented band. During late winter the band becomes worn exposing the colored rami. The most intensely pigmented breast feathers (usually those of Common Redpolls) lose their barbules as spring and summer progress.