Parapatric distribution of Common Flicker (Colaptes auratus)

Flickers occur in two color phases, a western "red-shafted" form and an eastern "yellow-shafted" form. The two were formerly considered separate species, Colaptes cafer and C. auratus, respectively. The dark band indicates a broad zone of hybridization, the wavy lines the approximate limits of the predominance of the two forms. (Futuyma 1998 after Moore and Price 1993)