Trochalopteron chrysopterum (Gould), apud Jerdon B. Ind. ii, p. 43; Hume, Rough Draft N & E no. 416.
The Western Yellow-winged Laughing-Thrush breeds, so far as is yet known, only in Nepal, Sikkim, and Bhutan, from all which localities we have quite young birds, but no eggs.
Dr. Jerdon says: "The eggs are greenish blue, in a nest neatly made with roots and moss." This, of course, is wrong, as the eggs are now well known to be spotted.
From Sikkim, Mr. Gammie writes: "The Yellow-winged Laughing-Thrush breeds from April to June at elevations from 5500 feet upwards. It prefers scrubby jungle, and places its nest in bushes about six feet or so from the ground. It is a broad, cup-shaped structure, neatly and strongly made of fine twigs and dry grass-leaves, lined with roots and with a few strings of green moss wound round the outside. Externally, it measures about 6 inches wide, and 4½ deep; internally 3¼ by 2½.
"The eggs are usually three in number."
Six nests of this species found between the 4th May and 2nd July in Native and British Sikkim were sent me by Mr. Mandelli. They were placed in small trees or dense bushes at heights of from 3 to 8 feet, and contained in some cases two, and in others three fresh or fully incubated eggs, so that sometimes the bird only lays two eggs. Three nests were also sent me by Mr. Gammie, taken in the neighborhood of the Sikkim Cinchona-Plantations. All are precisely of the same type, all constructed with the same materials, but owing to the different proportions in which these are used some of the nests at first sight seem to differ widely from others. Some also are a good deal bigger than others, but all are massive, deep cups, varying from 5·25 to 6·5 inches in diameter, and from 3 to fully 4 in height externally; the cavities vary from 3 to 3·5 in diameter, and from 2 to 2·5 in depth. The body of the nests is composed of grass; the cavity is lined first with dry leaves, and then thickly or thinly with black fibrous roots. Externally the nest is more or less bound together by creepers and stems of herbaceous plants. Sometimes only a few strings of moss and a few sprays of Selaginella are to be seen on the outside of the nest; while, on the other hand, in some nests the entire outer surface is completely covered over with green moss, not only on the sides, but on the upper margin, so as to conceal completely the rest of the materials of the nest, and in all the nine nests before me the extent to which the moss is used varies.
The eggs of this species are typically somewhat elongated ovals, some are much pointed towards the small end, others are somewhat pyriform, and others again are subcylindrical. The shell is fine and soft, but has only a moderate amount of gloss. The ground-colour, which varies very little in shade, is a delicate pale, slightly greenish blue, almost precisely the same colour as that of Trochalopterum erythrocephalum. The eggs are sparingly (in fact, almost exclusively about the large end) marked with deep chocolate. These markings are in some spots and blotches, but in many assume the form of thicker or thinner hieroglyphic lines. As a rule, three fourths of the egg is spotless, occasionally a single speck or spot occurs towards the small end of the egg. One or two eggs are almost spotless. In length the eggs vary from 1·1 to 1·23, and in breadth from 0·73 to 0·87, but the average of sixteen eggs is 1·17 nearly by 0·82.