The SALANGANE PROPER (_Collocalia nidifica_), as we will call the species
most extensively met with, is from four to five inches long, and twelve
inches broad. Its wing measures about four inches and a half, and its
tail two and a quarter. The plumage is of a greyish brown, paler upon the
under surface; the quills and tail are blackish, and the vicinity of the
eyes marked with white. The feathers of the adult have a slight metallic
lustre that is not perceptible in the young. It was formerly supposed
that these remarkable birds were only found upon the Sunda Islands, but
modern observation has proved that they also inhabit the mountains of
Assam, the Neilgherries, Sikkim, and Ceylon. Most contradictory tales
have been told by travellers as to the materials of which their famous
edible nests are composed.
The earliest account of these nests is met with in Bontius, who tells
us that "Large flocks of very small birds of the Swallow kind come down
during the breeding season, and settle upon the Chinese coasts, where
they swarm over the cliffs that overhang the sea. In these situations
they build their strange nests, forming them of fish spawn, which they
collect from the shore. These nests are much valued by the natives, who
will often pay very large sums of money for them, in order to make them
into soup, which is considered a dainty." More modern investigators have
been equally inaccurate in their surmises, some pronouncing them to
be constructed of the flesh of a kind of snail or worm, or a peculiar
species of sea-weed, gathered from the shore. Recent observations upon
this interesting point have, however, proved that all these explanations
are incorrect, and we learn that these luxuries, in which the Chinese so
much delight, are formed of a secretion resembling saliva, drawn from
under the bird's own tongue. After a great variety of experiments as to
its component parts, Marsden pronounces that the material resembles a
mixture of gelatine and white of egg, an opinion in which Bernstein, who
is a trustworthy authority on this disputed question, entirely coincides;
we will, however, describe the nest of the Salangane before we give our
readers the real secret of its construction, as vouched for and described
by the last-mentioned naturalist. The Salangane usually builds in such
deep and dark cavities that the observation of its proceedings as it
fastens its small, thin, gelatinous nest to the rock, is attended with
great difficulty. This structure is in shape like the quarter of an
egg-shell, divided longitudinally along its entire length. Some of these
nests are white, some of a brown colour, and opinion differs considerably
as to the reason of this variety; we ourselves believe it to depend on
the age of the structure, as we have never seen a brown nest occupied,
but other authorities pronounce them to be the work of two distinct
species. In the markets the white nests command a very high price, while
such as are dark are but little esteemed. The two white eggs laid by
the Salangane are deposited at the bottom of this remarkable gelatinous
receptacle, without any further preparation for their warmth or comfort.