Fig. 6

Plumage differences between the two taxa of Blue Chaffinches; (a) lateral view of five polatzeki (left) and eight teydea (right), (b) dorsal view of the same birds, (c) abdominal view of two polatzeki (left) and two teydea (right) specimens. Note the brighter wing bars, smaller body size and more whitish belly in polatzeki. The specimens were photographed in the collection of American Museum of Natural History, New York [see Additional file 2]