cry accompanies the act of coition, and, if so, it is important if the note is sometimes heard when the two sexes are swooping together. It seems to imply that coition may actually occur in the air.
The full rattle is also deserving of observation in relation to the song of the bird, for the greater part of the song is of much the same character as this exclamation; and it is probable that if this full sound had been originally employed during coition, it might have been afterwards employed for the purposes of suggestion, and in course of time might have been elaborated into a comparatively long strain. I venture to think that ornithologists will allow that I have elsewhere ('Evolution of Bird- Song') adduced some reasons for the theory of the development of certain songs (as well as certain alarms) from a repetition of short cries, and the song of the Chaffinch is not without indications of a similar history.
Dr. Butler tells me that the song of the Chaffinch is popularly rendered—
"In another month will come a Wheatear."
The first few notes never show much variation, and in early spring they may sometimes be heard in the form of mere repetitions of the "chirri." The middle of the song consists of a rattling repetition of the same character as the full rattle I have just described. The last syllables, "wheatear," have always seemed to me to be very interesting, as relating the song of the Chaffinch to those of the Greenfinch and Lesser Bedpoll. The "wheat" is greatly varied in loudness, and is very often wholly absent, or its place is occupied by a sound like "tissi."
Near Eltham, in April and May, some of the male Chaffinches have a loud single alarm-cry, "zee," which can be heard through all the chorus of birds. This note is sometimes given in the song, but only at one particular part. It then takes the place of the hard penultimate note, "wheat," and whenever given it ends the strain. I called the attention of Mr. A. Holte Macpherson to this note, and he, like myself, had never heard it elsewhere. It seems to me to be a survival from an earlier period. The Chaffinch seems to be losing all trace of this danger-cry, and to be developing instead the full love-rattle. The "chirri," and the "love-rattle," and the "zee," uttered in succession, would constitute an excellent "skeleton" of the Chaffinch's song, and especially so if the first two cries were each repeated a few times.
