A Blue Sunbird: Colour Variation As an Arid Climate Adaptation in the Malachite Sunbird Nectarinia Famosa

We observed, in a dense succulent thicket, a glossy blue-plumaged bird which we at first thought was a Cape Glossy Starling. We saw that this blue bird was accompanied by a sunbird with dark brown dorsal plumage and a white belly. The blue bird was then seen to be a sunbird as well. No matter which way it turned, clambering through the dense scrub, no green was observed, only a deep, royal blue. The blue bird was identified as a male Malachite Sunbird Nectarinia famosa, with aberrant plumage, and the second bird as a female of the same species. Why was typical metallic green plumage of this species blue? This paper makes suggestions. Birders need to be alert to this colour variation.