The genus Tribura contains five Indian species, of which four are alpine and one an inhabitant of the plains. The former do not appear to migrate beyond ascending the mountain-slopes in summer and descending them in winter; but the latter is probably a -migrant from distant regions, spending the winter in Burma and disappearing from that country in spring.
These Warblers are birds of plain plumage, and the feathers are very soft and silky in texture. Some species are spotted on the breast. The sexes are alike. The spring moult is complete or nearly so, and there is generally a slight difference between the summer and the winter plumages. The young birds are very yellow.
The species of Tribura frequent grass and bushes, and are great skulkers, and though fond of moisture they are not particularly aquatic in their Habits.
The five Indian species of this genus are not perfectly congeneric, one differing from the other four in its extremely large bill, whilst a second species is distinguished from the other three by the shape of the wing. I keep all five together, however, but subsequent workers will do well to investigate their claims to generic separation.
In T. major the bill is as long as the head ; in the other species only half the Length of the head; in all cases slender and straight. The rictal bristles are extremely minute and invisible without a lens. The forehead is very smooth, and free from all hairs &c. The wing is fairly long, the first primary varying from rather more than a third to half the Length of the second, which is long, but falls short of the tip of the wing. The tail is very much rounded, and the feathers are rather pointed. The tarsus is sufficiently long to enable these birds to hop about freely.
Key to the Species.
a. First primary much shorter than half the second
a1. Bill at gape .8…………………T. major, p. 362.
b1. Bill at gape .65…………………T. intermedia, p. 363.
b. First primary about half the Length of the second.
c1. Sides of the head and neck and the throat ashy, the latter spotted…………………T. thoracica, p. 363.
d1. Sides of the head and neck rufous; throat whitish, unspotted. a2. Breast whitish; lower mandible yellow throughout…………………T. luteiventris, p. 364.
b2. Breast grey; lower mandible dusky, almost black at base…………………T. mandellii, p. 365.