(312) Leioptila capistrata pallida Hartert.
THE SIMLA BLACK-HEADED SIBIA.
Leioptila capistrata pallida, Fauna B. I., Birds, 2nd ed. vol. i, p. 298.
This Western race of Sibia is found in the N.W. Himalayas from Hazara to Garhwal, the hills of which seem to form its Eastern limit.
Dodsworth, in an excellent account of this bird (Journ. Bomb. Nat. Hist. Soc. vol. xxi, p. 249, 1911) thus seems up its general haunts:— “ Hillsides and ravines covered with dense, moist forests, especially oaks and other large trees, thickly coated with moss, are its favourite resorts ..... It is very abundant in the neighbourhood of Simla. It frequents the outer ranges of these mountains between 5,000 and 8,000 feet, but is most plentiful at about 6,000-7,000 feet. It is a permanent resident throughout its habitat.”
Dodsworth’s description of the nests is very full and Hume’s, Marshall’s and Hutton’s descriptions of the nests they took are all covered by it:—
“The nests are generally built on trees or bushes on the edges of forest, though it is by means unusual to find them towards the middle, or in the heart of a thickly-covered hill-side.
“The nests are placed either at the ends of branches, or on one of the upper forks, or where several small twigs shoot upwards from a horizontal branch, and no matter what their position, they are, as a rule, well concealed. In fact they are very difficult nests to find, but the birds themselves sometimes give away the show by uttering a sharp twitter, if a person happens to approach too close to the tree containing the nest.
“So far as my experience goes, the trees which are preferred in Simla for nesting by these birds are either Oaks or Rhododendrons. Only once I have found a nest placed in a small Holly.
“The height of the nests varied from 8 to 60 feet, but the average of 17 nests was 26.1/2 feet.
“The nests are neat cup-shaped structures, composed exteriorly of a layer of moss, in which a good many leaves, strips of bark and cobwebs are occasionally incorporated, and lined interiorly with roots of the maidenhair ferns and other plants. One nest is of very unusual shape ; it is something like an inverted cone, and it is 7.1/2 inches in height. It was placed against the trunk of a medium-sized Rhododendron, and was beautifully concealed by some twigs shooting at right angles from below it.
“The materials composing the nest are firmly interwoven together, and the structures themselves are securely attached to the surrounding twigs. Some of the nests situated at the extreme ends of branches appeared to occupy most precarious positions but I have never yet known one to be blown down by the wind.
“Both birds share in carrying materials and in building operations. I have, however, noticed, on one or two occasions, that the cock brought the materials, and the hen alone was the architect. Once a site has been chosen, building operations progress with great rapidity, but I have not yet been able to ascertain the exact length of time taken by the birds in constructing the nest. When the latter has been completed a very short period seems to elapse before the first egg is laid.
“These Sibias desert their nests on the least provocation. So far as my experiences go I do not think that the cock takes any part in the hatching of the eggs.”
Mr. A. E. Jones also took many nests round about Simla at various elevations from 6,500 to 8,000 feet but, beyond the fact that most of his nests were built on Deodar-trees, there is nothing to add to Dodsworth’s description.
Although I have never taken a nest myself I have had many sent me, and of these the measurements outwardly varied from 4 to 6 inches across and from 3 to 5 inches in depth, the cup for the eggs being roughly 3 by 2 inches or rather less.
A few birds nest in May but the majority of them breed during June and July. Dodsworth, however, found a nest with two young on the 9th of May, so that, occasionally at all events, they must lay in the last weeks of April.
They lay two or three eggs but this race lays three more often than two. In colour they are, of course, indistinguishable from those of the preceding subspecies, but I have one or two clutches which are rather unusual. One clutch of three taken by Rattray at Murree has the smudges and blotches rather smaller than usual but very densely distributed over the whole surface, whilst another pair has the blotches practically absent but the lines longer and more numerous than in any other set I have seen. Erythristic eggs occur among those of this Sibia as in those of the birds already dealt with but not, I think, so often.
Fifty eggs average 25.5 x 18.3 mm. : maxima 28.0 x 18.8 and 26.0 x 19.4 mm. ; minima 23.1 x 17.8 and 24.4 x 17.1 mm.
312. Leioptila capistrata pallida
(312) Leioptila capistrata pallida Hartert.