towers and steeples are not sufficiently numerous, these birds build in
forsaken rabbit burrows. See a curious account of these subterranean nests
in White's History of Selbourn, p. 59. Can the skilful change of
architecture in these birds and the sparrows above mentioned be governed by
instinct? Then they must have two instincts, one for common, and the other
for extraordinary occasions.

I have seen green worsted in a nest, which no where exists in nature: and
the down of thistles in those nests, that were by some accident constructed
later in the summer, which material could not be procured for the earlier
nests: in many different climates they cannot procure the same materials,
that they use in ours. And it is well known, that the canary birds, that
are propagated in this country, and the finches, that are kept tame, will
build their nests of any flexile materials, that are given them. Plutarch,
in his Book on Rivers, speaking of the Nile, says, "that the swallows
collect a material, when the waters recede, with which they form nests,
that are impervious to water." And in India there is a swallow that
collects a glutinous substance for this purpose, whose nest is esculent,
and esteemed a principal rarity amongst epicures, (Lin. Syst. Nat.) Both
these must be constructed of very different materials from those used by
the swallows of our country.

In India the birds exert more artifice in building their nests on account
of the monkeys and snakes: some form their pensile nests in the shape of a
purse, deep and open at top; others with a hole in the side; and others,
still more cautious, with an entrance at the very bottom, forming their
lodge near the summit. But the taylor-bird will not ever trust its nest to
the extremity of a tender twig, but makes one more advance to safety by
fixing it to the leaf itself. It picks up a dead leaf, and sews it to the
side of a living one, its slender bill being its needle, and its thread