Layard, the habits of the Cape Promerops, its mode of nidification, and the character of its eggs are very unlike those of the ordinary Nectariniidae.
Of the many characteristic birds may be mentioned Pycnonotidae or bulbuls, of which the Phyllornithinae are peculiar, Campephagidae or cuckoo-shrikes, Dicruridae or drongos, Nectariniidae or sunbirds; pheasants, together with Pavo and Gallus.
The extensible tongue, though practically serving the same end in both groups, is essentially different in its quasi-tubular structure, and there is also considerable difference between this organ in the Nectariniidae and the Meliphagidae.
Those known to the older naturalists were for a long while referred to the genus Certhia (Tree-Creeper, q.v.) or some other group, but they are now fully recognized as forming a valid Passerine family Nectariniidae, from the name Neetarinia invented in 1881 by Illiger.