The genus Chaetornis was instituted by Gray for the reception of an Indian bird which is characterized by having the rictal bristles, five in number, arranged in a vertical series in front of the eye and by having the lores naked. It is doubtful whether the genus has a spring moult, but if it has, the moult is probably confined to the wings and a few of the body-feathers. The tail is not changed in the spring, and the colour of the bird is not affected; but abrasion of the feathers, to which it is very subject, causes a great variety of changes to be observed in this bird in the course of the year. The sexes are alike, and the young are richly coloured.
This bird, like Megalurus (to which it is closely allied), has the habit of rising singing into the air, and, like birds of that genus, affects grass and reeds and feeds a good deal on the ground. It is not a difficult bird to observe.
There are no supplementary hairs in front of the rictal bristles, and the feathers of the forehead are short and smooth. With this bird the series of Reed- and Grass-Warblers with twelve tail-feathers, and characterized by the firm plumage of the forehead, ends. The bird constituting the next genus, usually considered a Reed-Warbler, is not withstanding its habits, more closely allied to hypolais and sylvia than to Acrocephalus, Locustella, and Tribura. It commences the series of Warblers in which the feathers of the forehead are supplementary hairs in front of the rictal bristles; and all these Warblers are more or less arboreal.