Description wikipedia

The African yellow warbler (Iduna natalensis), also known as Natal yellow warbler, dark-capped yellow warbler or yellow flycatcher-warbler, is a species of Acrocephalidae warblers; formerly, these were placed in the paraphyletic "Old World warblers". The African yellow warbler is a medium-sized warbler in which the whole of the upperparts and tail are yellowish-brown, with a slightly browner crown and yellower rump. The wings have brown feathers edged with yellow. The underparts are bright yellow with an olive wash on the sides of the breast, flanks and lower belly. The bill is pale on the upper mandible and blackish on the lower, and the legs are blackish. Females have duller underparts, and the juveniles are similar to the males but are buffier. The total length is 13 cm (5.1 in) and the birds weigh between 10 and 15 g (0.35 and 0.53 oz). The song of the African yellow warbler is a rapid series of throaty and varied notes preceded by a few raspy notes, for example, "chip-chip-chip- whee-lee-wheeo". The alarm call is a sharp "tsk" or "chirr".