(933) Prinia flaviventris flaviventris (Deless.).
THE BHUTAN YELLOW-BELLIED WREN-WARBLER.
Prinia flaviventris flaviventris, Fauna B. I., Birds, 2nd ed. vol. ii, p. 528.
The Yellow-bellied Wren-Warbler is resident and breeds from the Nepal Terai and all along the foot-hills of the Himalayas to Assam, both South and North of the Brahmapootra. Thence it extends throughout Burma and the Malay States to Singapore and Sumatra. It is also common in the low-lying lands in Eastern Bengal. They are birds of the plains and foot-hills but wander some distance up the hills. In the Barail Range in North Cachar I have found them breeding at 3,500 feet near Laisung, quite commonly at 2,500 feet around Gunjong and, in the Khasia Hills, up to 3,800 feet in the Umiam Valley.
They were, fifty years ago, very common all round Calcutta and bred in numbers in the “Salt Lake” area, where Parker took several nests and, later, I did the same. In the plains it keeps much to grass-land, not necessarily of any extent, bushes and scrub on the edge of cultivation, and waste land of any kind but, undoubtedly, it prefers sites near water. It will often select a patch of weeds, grass and bushes in road-side ditches or irrigation ditches in fields, while I have known them breed in the grass and weeds on the “bunds” around rice-fields. They do not breed in gardens and parks unless these are very extensive and much overgrown, and I have only known of one such nest.
In the hills they generally breed in grass-lands which are much mixed with bushes and odd trees, or else in the secondary growth of deserted “jhums” (clearings in jungles). They particularly affect those on which cotton has been grown and on which the growth reappears very slowly and for a year or two very thinly. Rarely I have taken the nest from beside jungle-paths or from the sides of streams running through forest.
Tickell speaks of a nest which was “pensile but quite Open, being a hemisphere with one side prolonged.” I have never seen such a nest, and all the many I have seen have been similar to that taken by Parker in the Salt Lake and described in Hume’s ‘Nests and Eggs’ (vol. i, p. 289):—“This bird breeds in the Salt-Water Lake, or rather on the swampy banks of the principal canals that intersect it. The nest is nearly always placed in an ash-leaved, shrub-like plant growing on the banks of the canal and overhanging the water. One taken on the 26th July, 1873, containing four nearly fresh eggs, was almost touching the. water at high tide. The male has the habit, when the female is sitting, of hopping to the extreme point of a tall species of cane-like grass, which grows abundantly on these swamps, whence he gives forth a rather pleasing song, erecting his tail at the same time, after which he drops into the jungle and is seen again no more. It is almost impossible to make him show himself again.”
Parker was quite right about making this bird show himself, but one has only to keep quiet and still and in a few minutes up he comes again and repeats his little song.
The nests may be built in grass, weeds or in bushes. About the Salt-Water Lake Parker found all his nests in a semi-creeper plant (Derris scandens) which covers the banks of the canals. I found my nests both in this and in tufts of grass. When placed in bushes or weeds the birds often select pendent twigs, but in grass they are fixed to the upright stems, two or three feet from the ground. It may be attached to several twigs or stems or only to two or three but, invariably, part of the material of which the nest is made is coiled round the supports very efficiently, if loosely.
The nest is always domed, often egg-shaped, but generally an oval equally broad at top and bottom. It does not vary much in size and nine nests out of ten are between 4.1/4 and 4.3/4 inches in height by about 2.1/4 to 2.1/2 in breadth ; the walls are very thin and the egg- chamber measures, roughly, 3.1/2 inches high by about 2 in diameter. The entrance is close to the top and in some nests the materials project above it. The nests are made of grass, both stems and fine shreds of blades being used for the purpose. Sometimes the flowering ends, denuded of the soft white down, are also woven in, but the thick seeding ends with the down are never incorporated, as in the nests of the Suyas. There is no lining but the inner part is made almost wholly of fine stems, and the whole structure is strengthened by cobwebs and silk, which are also employed in attaching the nest to the supports.
The breeding season is from July to September over the greater part of its range. Oates found them breeding in Pegu from May to September and Coltart took nests in Margherita in April after the early rains. Few birds, however, breed until the true rains have broken in the middle of June. The earliest full clutch I have taken was on the 31st May, and I have found them with fresh eggs up to the 3rd October.
The full complement of eggs is four, rarely three. I have never seen a five, but took six from the first nest I ever found.
In colour the eggs are a brilliant mahogany-red, very highly glossed. In a few eggs there is a deeper flush at the larger end and I have two clutches which are paler than usual over two-thirds of the surface, but with deep mahogany caps at the bigger third.
In shape the eggs are broad, blunt ovals, the texture very fine, close and strong for such tiny eggs.
Sixty eggs average 15.2 x 11.7 mm. : maxima 16.4 x 11.9 and 14.5 x 12.5 mm. ; minima 14.2 x 11.6 and 16.1 x 11.0 mm.
Both sexes take part in building the nest, but the male only incubates for short spells morning and evening.
933. Prinia flaviventris flaviventrls
(933) Prinia flaviventris flaviventris (Deless.).