The abode of the KUSAPPI (Collocalia fuciphaga) is much more easy of access than that of its congener above described, as it is either placed at the bottom of a hole, or affixed to the naked rock. In shape it resembles that of the Salangane, but its walls are partially composed of stalks of plants, horsehair, and blades of grass, not woven, but cemented together with the aforesaid gelatinous secretion, by which it is also attached to the surface of the cliff. The amount of the mucilaginous substance used varies considerably, some nests being in great measure composed of it, whilst such as are formed of very pliable extraneous materials are made to a certain extent without its aid. Bernstein gives the following account of the process of building the nests of the Kusappi, and has proved the accuracy of his statements by numberless experiments, having even drawn the slimy thread himself from the bird's beak. "Shortly before the breeding season," says Bernstein, "the glands beneath the tongue of these birds become unusually distended, and present the appearance of two large swellings, which diminish considerably in size after the nest is completed. When about to make the foundation of its future abode, the Kusappi presses its tongue against the rock that is to serve for a support, and then, retiring a few paces, draws out a long gummy thread, which dries with great rapidity; this process is repeated, until a crescent-shaped mass is formed, and firmly fastened to the stone. The bird then takes the blades of grass, or stalks of other plants, one after another, from a heap it has already prepared, and cements them together by a similar operation, producing, as it turns its head from side to side, in order to draw out its thread, the undulating lines so frequently seen upon these remarkable structures, and this process is continued until the nest has assumed the necessary dimensions." The Salangane's method of proceeding is essentially similar to that adopted by the Kusappi, but, as we have already said, it builds entirely with the gelatinous threads, without any foreign admixture. We have frequently remarked that such of these birds as are well fed exhibit a much more considerable enlargement of the glands than is observable in those that have only been able to obtain a scanty supply of nourishment. This fact explains the reason why so much difference is constantly noticeable both in the size and beauty of these much-prized nests, millions of which are annually consumed, such as are very clear and delicate often realising fabulous prices. Java is particularly rich in this article of commerce, and Epp thus describes one of the localities in which the nests are most numerously met with:—"The Karang Kallong," he says, "is a huge chalk rock, rising perpendicularly from the sea, by which it is surrounded, and is garrisoned with a force of twenty-five men, whose sole duty is to protect the birds while building. A large tree grows at the edge of the steep, and from this point of view those who venture to look down behold the busy workers swarming beneath, appearing in the distance no larger than bees. The sides of the precipice contain nine caverns, each of which has its name, and can only be entered by a man lowered from above; should the rope break, his death is inevitable, and even if this danger be escaped, the task of finding the entrance to the cavern is attended with great peril, as the foaming waves constantly dash high enough to conceal it from view. The natives who engage in this terrible undertaking fortify themselves for their task by a dose of opium, and offer up a prayer to the Goddess Njaikidul before making the descent." In 1847 no fewer than 2,700 people inhabited the summit of the Karang Kallong, and of these 1,500 men were thus employed. Enormous numbers of nests are exported annually from this place to China, and are sold at very high prices; but those who thus risk their lives to obtain the expensive luxury are but poorly remunerated. We are but little acquainted with the habits of these birds, except that they fly with great rapidity, and constantly frequent the sea-shore.
THE STEEPLE SWIFT (Cypselus apus).
The PRICKLY-TAILED SWIFTS (Acanthylis) are distinguished from other members of their family by the very peculiar construction of their tail-feathers, the shafts of which extend beyond the web; the plumage is also thicker, and the tarsi longer and more powerful than in most other species.
THE WHITE-THROATED PRICKLY-TAILED SWIFT.
The WHITE-THROATED PRICKLY-TAILED SWIFT (Acanthylis caudacuta) is about eight inches and a half long, and twenty broad; the wing measures eight and the tail two inches. The head, upper tail-covers, sides of the wings, quills, and tail are pale black, with a metallic greenish blue gloss; the back and shoulder-feathers are whitish brown, the breast and nape white. The under side is blackish brown, the lower wing-covers and a streak on the side of the head are white, more or less intermixed with glossy, blackish blue feathers. The inner web of the secondary quills is also white; the beak is black, the foot lead-colour, and the eye deep brown.
We learn from Jerdon that this species is found in the south-eastern provinces of the Himalaya, Nepaul, Sikkim, and Bhotan, and that its flight is extraordinarily light and rapid. The breeding settlements are generally at a considerable height in the mountains, but always below the snow boundary. The strange prickly tail appears to be employed to assist the bird while climbing. Further particulars as to its habits and mode of life are entirely wanting.
THE DWARF SWIFT.