Redpoll

The redpolls (in Britain also historically known as redpoles) are a group of small passerine birds in the finch family Fringillidae which have characteristic red markings on their heads. They are placed in the genus Acanthis. The taxonomy of redpolls is unsettled, with several different very closely related forms of redpolls which have been considered as anything from one to five species. Some studies favour three species, but this is certainly not definite. Global lists currently support either two species (Common and Hoary Redpoll) or a single species (Common Redpoll). Most recently, genomewide analyses found differences in gene expression but no genetic divergence, suggesting that plumage forms have originated recently, within a single interbreeding lineage, and do not represent species boundaries.