[Illustration: THE WHITE-THROATED PRICKLY-TAILED SWIFT (_Acanthylis
caudacuta_).]
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.
[Illustration: 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.