Anomalospiza imberbis
Being a brood parasite, this bright yellow, weaver-like finch spends September to April finding unsuspecting cisticola (or tawny-flanked prinia) nests in which to lay its eggs. Their small size, bright yellow colour and short, stubby bill separate them from weavers, bishops and quelia.
This awesome bird is an uncommon summer migrant, which can be very difficult to locate. I first recorded it with Skye Hartog in February 2011 at the beginning of the Zaagkuildrift to Kgomo Kgomo birding route. Other good spots for it are the birding roadside routes south of Devon as well as Suikerbosrand Nature Reserve.