Shades of David & Goliath

A few days ago, toward the end of a morning run that had been fairly sparse in the bird-sighting department, I noticed a flurry of wings in the branches of an albizia tree overhead. A sizable bird, obviously a raptor of some sort, was scarcely avoiding being overtaken by a much smaller pursuer. Both found perches in the tree, having arrived, it seemed, at a temporary stalemate. Once they got settled, I was able to peg the larger of the two as an African goshawk (Accipiter tachiro) and its antagonist as an African little sparrowhawk (Accipiter minullus). The dimensional disparity was striking -- I'd never seen individuals of the two species in the same tree -- one crow-sized and the other barely larger than your average thrush. Both of these accipiters are agressive hunters, but I'm not sure what precipitated the harassment of the goshawk by its diminutive cousin. Perhaps the little sparrowhawks have a nest in the neighborhood?