(313) Leioptila gracilis (McClell.).
THE GREY SIBIA.
Leioptila gracilis, Fauna B. I., Birds, 2nd ed. vol. i, p. 298.
This beautiful and graceful bird is found throughout the hills South of the Brahmapootra in Assam, Manipur and the Chin Hills between 4,000 and 7,000 feet. In the Khasia Hills it is common between 4,000 and 6,000 feet wherever there are Pine forests, to which it seems to be restricted.
Godwin-Austen took this Sibia’s nest in the Khasia Hills in the Umiam Valley at an elevation of about 4,000 feet. “In the pine forest that covers the slopes of the hills descending into the Umiam Valley in Assam, one of my men marked a nest on June the 25th ; I proceeded to the spot soon after I had heard of it, and on coming up to the tree, a pine, saw the female fly off, out of the head of it. But the nest was so well hidden by the boughs of the fir that it was quite invisible from below. The birds after a short time came back and then I saw it was Sibia gracilis ; but it was shy and, seeing us, went off again. The female, however, would not venture back and I sent one of my Goorhkas up, to cut off the head of the fir, nest and all, first taking out the eggs. It contained three eggs of a pale sea-green, with ash-brown streaking and blotchings all over.
“The nest was constructed of dry grass, moss and rootlets, and the green spinules of the fir were worked into it, fixing it most firmly in its place in the crown of the pine where it was much forked.”
For more than fifty years no other nest of this bird was taken but, on my being posted to the Khasia Hills, I made a very special search for the birds and their nests. I soon found the former, already evidently paired and breeding, but the nest for a long time eluded both myself and my Khasias, first-class men, who knew the hill-birds and their habits well. Determined not to bo beaten, we carefully examined the Shillong road to the Umiam Valley by which Godwin-Austen had travelled so many years before, when he went to view the nest which had been marked down for him. There in the Pine-trees at the bottom of the hill, and just above the stream, a pair of birds were seen within a very few yards of where Godwin-Austen must have found his nest and, presently, in front of the watchers, one of these disappeared into the crown of a tall Pine just below where they stood by the side of the road. No nest was visible from any point from which the tree could be examined but, on tapping it, away went the bird, and within a very few minutes a Khasia had climbed the Pine and announced a nest with eggs.
After this every year we were successful in getting a few nests but, though the birds were common in some places, the nests were so hard to find that many must have escaped us. In one or two instances nests were built on small branches close to the main stem of the tree, but all the others were built into the crown of the Pine in the final clusters of pine-needles, which, surrounding them on all sides and built into the nests themselves, completely hid them from the closest scrutiny.
So far as I know the birds seem to have no special predilection for any particular kind of situation. As long as it is a Pine-tree they do not seem to care whether it is one in heavy or light Pine forest of whether it is one of a small cluster of trees standing on the outskirts of the heavier forest.
The nests are very well made deep compact cups, about six inches in diameter and about four in depth. The walls are made of moss- roots, a few leaves and fibres mixed with both dry and green moss and completely covered outside with the latter. Occasionally a few tendrils are wound through and under the outer moss but this is not always so. The lining is of a black fungoid rhizomorph or of fine roots, generally black moss-roots, sometimes mixed with a few red fern-roots.
Hopwood, Mackenzie and Wickham found them breeding in the Chin Hills at about 6,000 feet on Pine-trees. The nests seem to have been very similar to those found in the Khasia Hills, though Mackenzie describes the linings as being made of “fine grass, seed-stems and rootlets.”
In the Khasia Hills they breed in May and June. One nest found on the 19th August was probably a second brood. In the Chin Hills they seem to breed late in April and early May.
The eggs number two or three, one as often as the other, whilst I have also seen about half a dozen clutches of four taken during the last thirty years, mostly by my Khasia collectors since I left India.
Nine eggs out of every ten are a pale bluish- or greenish-grey in ground-colour, lightly freckled all over with reddish-brown or dark brown, generally rather more numerous at the larger end than elsewhere and occasionally forming a denser patch—one cannot call it a cap—at the larger end, but I have seen no eggs in which the markings form a ring. In density of marking and in depth of colour the eggs vary a good deal and some few eggs are very lightly marked. The next most common type is that in which the freckles become well defined though small blotches, less numerous than in the freckly type, and standing out much more than the freckles in contrast with the ground-colour. Aberrant eggs, in a few cases, show a close approximation to those of L. capistrata, whilst in others they are much like the eggs of Actinodura. Erythristic eggs occur occasionally among those of this species, the few
I have seen having all been of the freckly type, the ground being white or pinky-white and the markings reddish.
Sixty eggs average 23.9 x 17.7 mm. : maxima 26.3 x 17.5 and 23.9 x 19.0 mm. ; minima 22.0 x 17.5 and 22.5 x 16.6 mm.
Both sexes take part in incubation and in feeding the young. The male also assists in building, certainly bringing most of the material to the site and sometimes actually placing some of it in position. Both sexes have been several times trapped on the nest and they are easy to snare, though very shy and always refusing to return to it whilst anyone is in sight. They sit close but, when once disturbed, ate very loth to return. Incubation probably takes fourteen days but I am not certain ; three eggs found in a nest on the 20th June and looking as if absolutely fresh—there were only two on the 18th—were hatched on the 3rd, the chicks apparently just out of the shells, though these had already been taken away by the parents.
313. Leioptila gracilis McCIell
(313) Leioptila gracilis (McClell.).