No evidence of genetic differentiation between lesser redpolls Carduelis flammea cabaret and common redpolls Carduelis f. flammea

The redpoll finch complex Carduelis flammea-hornemanni has received much attention from taxonomists due to its remarkable variation in plumage and morphology. Some authors have suggested one highly variable species, flammea, while others have suggested seven species (see Knox 1988 for review). The most widely held view recognises two species, the common redpoll (including flammea, islandica, rostrata and cabaret) and the arctic redpoll (including hornemanni and exilipes). The distribution range of the common and the arctic redpolls includes the higher latitudes of the Holarctic, where the two forms breed sympatrically over large areas (Knox 1988). Observations of intermediate birds have been put forward as evidence of hybridisation, but due to improved knowledge of plumage variation, most ‘intermediate’ redpolls can now be unambiguously assigned to a species identity (Molau 1985, Knox 1988). The most distinctive redpoll form, the lesser redpoll C. flammea cabaret was until recently restricted to Britain, Ireland and the Alps. This form has recently expanded its breeding range towards Scandinavia and is now breeding sympatrically with flammea in southern Norway in years when flammea is breeding in the lowlands (Lifjeld & Bjerke 1996). Assortative mating has been found in one area in Norway and the latest recommendation was therefore to split cabaret as a distinct species from flammea (British Ornithologists’ Union 2001, Knox et al. 2001). While difNo evidence of genetic differentiation between lesser redpolls Carduelis flammea cabaret and common redpolls Carduelis f. flammea