NOTES ON THE BREEDING OF THE CHAFFINCH.
Some years ago, a friend who had bred many hybrid Finches of different kinds told me that hybrids could not be obtained from the Chaffinch, because that bird would not breed in confinement, a flight being necessary for the union of the sexes. This information, and the frequent exhibition of a swooping flight by a pair of Chaffinches, led me to conclude that the swooping flight might be really necessary to the breeding of the Chaffinch; and it may be mentioned that Mr. W.H. Yale, in his 'Handbook of Hybrid Birds' (1896), records that he has not been able to find an authentic instance of a Chaffinch mule.
My present purpose is to offer some remarks on the question whether a love-flight is necessary to the Chaffinch. By "love-flight" I do not mean the common straight Cuckoo-like flight of the male when he is leading a female from tree to tree, and flying with a constant and even succession of wing-beats; but I mean the swooping flight performed by both birds together, in which they are very near each other, if not actually in contact.
During this swooping, the birds always utter the call-note which they particularly address to each other and to their young. It is a little soft sound, something like "chirri" pronounced very rapidly. In April and May this note may be constantly heard. But during the love-flight another sound is sometimes uttered, and this deserves very close attention. Perhaps the simplest mode of describing it will be to give a few instances of its occurrence.
On April 5th, 1896, a pair of Chaffinches near each other in an Austrian pine in a garden at Stroud, in which tree the species nests nearly every season, were uttering the love-call, "chirri."
They suddenly darted forth and swooped and swerved close together, both of them uttering the call many times; and during the flight the whole song was given by one of the birds (doubtless the male), but in a hurried manner, ending in a very full low rattle, seemingly lower in pitch than the usual termination of the
