(344) Ixulus occipitalis (Blyth).
THE CHESTNUT-HEADED IXULUS.
Ixulus occipitalis, Fauna B. I., Birds, 2nd ed. vol. i, p. 321.
The Chestnut-headed Ixulus is found as far West as Garhwal and thence Eastwards on the Lower Himalayas through Nepal, Sikkim, and Bhutan to the extreme East of North and South Assam, Manipur and the Chittagong hills-tracts.
Gammie found it breeding at Rungbee, Sikkim, at about 3,000 feet ; Stevens never came across it in Sikkim but found it not uncommon in the Abor-Miri Hills and even in the plains adjacent to the hills in Winter. In South Assam it was a common bird in the humid evergreen forests between 3,000 and 5,000 feet but, although doubtless it often bred much higher, I never found its nest under 2,500 feet. Like so many other birds which breed in deep forest, they prefer little open, or comparatively open, spaces in which the greater trees thin out and let the light in. Mountain streams, perhaps so small that in places the foliage almost meets overhead, jungle paths etc. are favourite haunts, and I have taken several nests within a yard or two of village tracks. The site selected for the nest varies a good deal, and with the site the nest differs also. Some nests are built a few feet up in forest trees overhung with luxurious green moss, and in these the nest seems generally to be domed or nearly so, made of the moss with which the tree is covered and SO neatly tucked away among it that it is almost impossible to say what is nest and what is living moss. The lining in this and in nearly every other case is of fine fern- and moss-roots only.
Another place often selected is a mossy bank, overgrown with bracken, ferns, caladiums and other plants, in among which the nest is snuggled down in some hollow, a deep cup of moss with a few roots and odd dead leaves worked in, well protected overhead by some thick bunch of bracken and looking just like the mossy, leaf-strewn bank all round it. Sometimes it is built in among boulders and rocks or, occasionally, against the face of a moss- or fern-covered rock. In these positions the nest may be cup¬shaped if well protected above but otherwise it is domed or semi¬domed. The materials are generally moss mixed to a less or greater degree with dead leaves, roots and bits of bracken and, occasionally, almost entirely of these materials.
Some nests are, however, placed low down in bushes or tangles of wild raspberries, and such nests almost invariably are cup-shaped and made more of leaves, bracken and roots, bound together with tendrils and long creeper-stems. Sometimes moss is worked into the outside, but seldom so as to cover the whole of the nests, as in the other types.
The domed nests average roughly, in external diameter, about 4 inches and in height about 5 ; some are, however, decidedly smaller, and I have one measuring only 3.1/2 by 4 inches. The cup¬shaped nests may be as much as 3.1/2 inches from lip to lip, and roughly about half as much in depth.
Both birds assist in building the nest and both assist in incubation. They are shy little birds, but a pair were once found by me building a nest in a road-side tree, in among the moss growing all over the trunk. It was easy to hide and watch the birds at their work and, by the second day, they became so used to my sitting within about five yards of them that they went on with their work without paying any attention to me.
Both birds bustled in and out of the moss, tugging away at the pieces which they fancied but, in at least three out of four times, rejecting it again. They disturbed no moss within a little distance of the nest but seemed to collect most from the opposite side of the trunk. The male evidently took part in the actual building for, though it was almost impossible to see exactly what he did, he used to disappear with his material and come out again without it. The nest was very quickly built ; half finished only when first discovered, it was completed, lined and roofed-in in the next 48 hours and the first egg deposited the next day, and on my return seventeen days later contained three lusty young birds.
The breeding season is throughout May and June but I have taken eggs both in April and July, though I do not think they are normally double brooded.
The number of eggs laid is four, occasionally only three, never, so far as I know, five, though the Nagas, who are wonderfully reliable field-naturalists, say that this number is sometimes laid.
Looking at a series of eggs of this bird one gets the impression that they are a glorified lot of Swallows’ eggs, very heavily and handsomely marked. The ground is a pure white, in a few cases only faintly tinged with brown. The markings consist of primary blotches of brown varying from slightly reddish-brown to a deep umber-brown. These blotches are sometimes numerous over the whole surface though, nearly always, thickly scattered at the big end. In some they are decidedly more numerous at this end and in a few they are thick here and sparse elsewhere. Normally there are no secondary marks, but a close examination of a few eggs may show pale brown marks underlying the top layer of calcium. One abnormal clutch taken by myself has the marking confined to a deep brown cap at the extreme larger end, whilst in a second clutch one egg has large smears and blotches of brown, one is marked in the usual manner and two are intermediate.
In shape the eggs are long ovals, compressed towards the smaller ends but never very pointed. The texture is fine and smooth but glossless, though a few of the least-marked eggs have a Smooth sheen on their surface.
Sixty eggs average 19.3 x 14.2 mm. : maxima 21.3 x 14.0 and 20.1 x 15.0 mm. ; minima 17.3 x 14.0 mm.
344. Ixulus occipitalis Blyth
(344) Ixulus occipitalis (Blyth).