Morphological differentiation of Icelandic Redpolls, Acanthis flammea islandica

Abstract

Capsule The analyses support the grouping of the three Acanthis species, although a large split is observed between the A. hornemanni subspecies.Aims To investigate the morphological variation in A. f. islandica among different periods of the year and its morphological differentiation from the other subspecies A. f. flammea and A. f. rostrata, and also from the redpoll species, A. cabaret and the two subspecies of A. hornemanni, exilipes and hornemanni.Methods The subspecies status of the Icelandic population was evaluated with Amadon's rule, by comparing its variation of traits to the distribution of the traits in different species/subspecies of the group.Results A. f. islandica is characterized by intermediate wing, bill and tail lengths. Based on the 75% rule, wing length and bill depth can be used to discriminate A. f. islandica from both extreme morphs of redpolls (currently classified as different species); A. hornemanni and A. cabaret, and tail and wing length can distinguish A. f. islandica from its conspecifics A. f. flammea. The overall morphological divergence within the redpoll complex is not supported by association to the studied nuclear markers.Conclusion The taxonomic status of the three redpoll species is supported by Amadon's rule, however the subspecies status of the Icelandic Redpoll remains unclear.