The Esculent Swallow. BIRDS. The Esculent Swallow. 285 
species engaged in the production of the edible nests 
will be found to correspond with the description of the 
illustrious Swede ; there being several concurrent testi- 
monies in the works of the older travellers and natu- 
ralists, to the effect that the Esculent Swallow has 
white spots on the tail feathers. Should this prove 
correct, there will be at least three known species of 
these birds, namely — 
Collocalia esculenta of Linna;us ; 
CoUocalia fwiphciga of Thnnberg (since described by Mr. 
G. R. Gray as C. nidifica, on the ground that Thun- 
berg’s name is erroneous) ; and 
Collocalia lAnchi of Horsfield and Moore, a species very 
nearly allied to O.fuciphaga. 
Although, as already stated, Thunberg had adopted' 
the notion that these Swifts procured the materials of 
their nests from the sea-weeds cast upon the shore by 
the waves, and other writers maintained a somewhat 
similar opinion, namely, that the glutinous matter 
was derived from the spawn of fishes or the bodies 
of mollusca, the Rev. J. Hooyman published in 1781 
a paper, in which he completely disproves these 
views, and approaches very nearly to the true solu- 
tion of the problem. He declares that the food of 
the birds consists of insects — a statement which has 
been confirmed by subsequent observations. He de- 
scribes the habits of the birds as very similar to those 
of the other Swifts ; they resort during the day to 
marshes, inland lakes, and plains, over which they 
hover in pursuit of the insects which abound in such 
situations; and it is difficult to suppose that those 
numerous individuals which inhabit the interior of such 
large islands as Java and Sumatra would undertake 
a journey to the sea-coast and back in search of the 
materials for their nests. Mr. Hooyinan’s idea of the 
mode in which the glutinous material of the nest is 
procured is, that it is elaborated from the food of the 
bird, by a peculiar organic effort resembling secretion. 
In this it will he seen that he was not far from the 
truth, for Sir Everard Home and Mr. Blyth both state, 
that the glutinous matter is undoubtedly a secretion 
from the enormously-developed salivary glands, and 
chemical analysis of the nests has confirmed this 
conclusion. 
We have stated above that the Collocalice producing 
edible nests are found in great numbers both on the 
Indian continent and in the islands ; but it is principally 
in Java that any information as to the natural history of 
the birds and the mode of collecting the nests has been 
obtained. This island appears to be peculiarly adapted 
for the dwelling-place of these birds, which congregate 
in large flocks in caverns and fissures of the rocks, and 
build their nests upon the walls of these. Both in the 
interior and on the coast extensive hollows are formed 
abundantly in the rocks, probably caused to a consider- 
able extent by the volcanic action to which the island 
is so subject. Here the Swifts swann in vast flocks, and 
the management of the nests, especially in the caverns 
of the southern shore of the island, is laid down by 
regulations established by the 'government. So well 
is this singular harvest regulated, and so well has 
experience taught its managers the conditions under 
which it is to be realized, that the average quantity of 
nests to be expected from each cave may be estimated 
before the season for gathering them, with remarkable 
accuracy. 
The collection of the nests is undertaken in Java at 
three periods in the year. The principal harvest is 
gathered in the month of October, after the birds have 
been left undisturbed for about six months ; the other 
two gatherings are in December and March, so that 
there are two intervals of three, and one of six months, 
between the gatherings. The shorter periods scarcely 
allow tlie birds time to build their nests and bring their 
progeny to maturity, so that both in December and 
March great numbers of young birds are necessarily 
destroyed ; on the other hand, the nests obtained at 
these gatherings are of superior quality, clean and 
white, and very free from any extraneous matters. 
During the longer interval of six months the birds are 
enabled to rear two broods ; thus the quantity of nests 
becomes very large, and the maintenance of a sufficient 
number of the birds is provided for. In collecting the 
nests, various contrivances in the shape of ladders 
and scaffolding are necessary; and notwithstanding 
these aids, the gatherers appear to be exposed to con- 
siderable risk. 
The number of nests collected in Java is very great, 
the quantity passing annually through the market of 
Batavia on its way to China being estimated by both 
Raffles and Craufurd at two hundred peculs, or two 
hundred and fifty hundredweights ; but this is nothing 
in comparison with the Sooloo Archipelago, which 
produces no less than five hundred and thirty peculs. 
The total value of the edible birds’ nests imported into 
China is said to be 1,263,570 Spanish dollars, or 
£284,290 sterling. This, however, can give us but an 
imperfect clue to the actual quantity of this article of 
luxury wliich finds its way to the Chinese markets ; 
the price paid for the nests varying greatly according 
to the quality of the different samples. Thus the best 
and purest sorts fetch 3500 Spanish dollars per pecul, 
or about £5 10s. per pound ; the second quality will 
not bring more than 2800 dollars ; and the third only 
fetches about 1600 dollars. These prices will give 
some notion of the way in which these birds’ nests are 
prized in China, but they still only indicate the value 
at the place of importation. This value increases to a 
very considerable extent as the delicacies are conveyed 
away from the coast, and we are told tliat in some 
parts of China, a catty, or about one pound and a 
quarter of these nests, has fetclied no less than 40 
Spanish dollars, equivalent to £9 sterling. 
Family III.— HIRUNDINID^. 
In this family, which includes the well-known species 
of true Swallows, we meet with characters very similar 
to those presented by the Swifts, which form the pre- 
ceding family. The differentia] characters of these 
two groups were, to a certain extent, indicated under 
the head of the Cypselidae, so that -we need not dwell 
upon them here at any length. In their general form 
the Swallows closely resemble the Swifts, as they do 
also in their mode of life ; but their wings are shorter 
and broader, their nostrils of small or moderate size, 
