Figure 1.

Plumage and bill colour variation in the red-billed quelea. Throughout their non-breeding season, queleas are sexually monomorphic. Female queleas lose the carotenoid coloration of their bare body parts prior to the breeding season, while breeding males retain this coloration and also moult into a bright nuptial plumage that is polymorphic for both breast colour that varies from red to buff and for face colour that varies from white to black. Flank feathers, used here as controls, never contain carotenoids in any male plumage.