The following extract from a Letter of the Rev. Mr. J. Darwin, of Carleton Scroop in Lincolnshire, authenticates a curious fact of this kind.  “When I mentioned to you the circumstance of crows or rooks building in the spire of Welbourn church, you expressed a desire of being well informed of the certainty of the fact.  Welbourn is situated in the road from Grantham to Lincoln on the Cliff row; I yesterday took a ride thither, and enquired of the rector, Mr. Ridgehill, whether the report was true, that rooks built in the spire of his church.  He assured me it was true, and that they had done so time immemorial, as his parishioners affirmed.  There was a common tradition, he said, that formerly a rookery in some high trees adjoined the church yard, which being cut down (probably in the spring, the building season), the rooks removed to the church, and built their nests on the outside of the spire on the tops of windows, which by their projection a little from the spire made them convenient room, but that they built also on the inside.  I saw two nests made with sticks on the outside, and in the spires, and Mr. Ridgehill said there were always a great many.

“I spent the day with Mr. Wright, a clergyman, at Fulbeck, near Welbourn, and in the afternoon Dr. Ellis of Headenham, about two miles from Welbourn, drank tea at Mr. Wright’s, who said he remembered, when Mr. Welby lived at Welbourn, that he received a letter from an acquaintance in the west of England, desiring an answer, whether the report of rooks building in Welbourn church was true, as a wager was depending on that subject; to which he returned an answer ascertaining the fact, and decided the wager.”  Aug. 30, 1794.

So the jackdaw (corvus monedula) generally builds in church-steeples, or under the roofs of high houses; but at Selbourn, in Southamptonshire, where 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.