This is a Malachite Sunbird in non-breeding male plumage. It was a thrill to see and photograph this species tempered with the disappointment of not seeing one in full irridescent breeding plumage when they are a glossy combination of bright shiny greens. You can just about see a few green feathers on the breast amongst the yellow.  This one was hawking insects from the side of a building which was interesting to watch. If I spent more time in South Sfrica I would concentrate my attentions on the Sunbirds, they are a stunning family of birds.