Common Redpoll (Carduelis flammea) - HBW 15, p. 564

Taxonomy: Fringilla flammea Linnaeus, 1758, Norrland, Sweden.
Previously placed in genus Acanthis. Was until recently considered conspecific with C. cabaret, and evidence from mitochondrial DNA suggests that the two, together with C. hornemanni, are probably best regarded as closely related sister-species or forming a superspecies; despite wide genetic variation within their ranges, however, recent studies have found little support for lineage division between arctic-breeding and boreal-breeding redpolls, and comprehensive review of gene flow still required in order to determine species limits; pending conclusions of any review, may need to be reclassified within Acanthis. Present species hybridizes with C. hornemanni in N Norway and has hybridized with C. cabaret. Nominate race intergrades with rostrata in E Canada (NE Labrador and S Baffin I); intermediates described as race fuscescens. Proposed race holboellii (described from C Germany) considered a longer-billed and slender-billed variant of nominate with slightly longer wing and tail and slightly deeper pink of adult male; may predominate along N edge of Asian breeding range from Yamal Peninsula E to NE Siberia and in winter in Russian Altai, but intergrades with nominate occur in W Europe. Affinities of Icelandic population, which includes dark and pale birds, unclear: dark birds, similar to rostrata in size and plumage (but with bill and wing slightly shorter and slightly paler rump), proposed as race islandica, but differences considered too slight to warrant separation; pale birds similar in plumage and bill size to C. hornemanni (but usually separable by buffish, not white, wingbars and edges of flight-feathers and heavier streaks on underparts) and in wing and tail measurements to race rostrata of present species may have originated in Iceland, but now apparently rare and widely replaced by invading rostrata, although intermediates occur; further study required. Two subspecies recognized.