now it is clear again, but so modulated that the sound seems to come
from a great distance."[2]

[Footnote 1: Two races of the pine-wood sparrow are recognized by
ornithologists, _Pucaea aestivalis_ and _P. aestivalis bachmanii_, and
both of them have been found in Florida; but, if I understand the matter
right, _Pucaea aestivalis_ is the common and typical Florida bird.]

[Footnote 2: _Bulletin on the Nuttall Ornithological Club_, vol. vii. p.
98.]

Not many other birds, I think (I cannot recall any), habitually vary
their song in this manner. Other birds sing almost inaudibly at times,
especially in the autumnal season. Even the brown thrasher, whose
ordinary performance, is so full-voiced, not to say boisterous, will
sometimes soliloquize, or seem to soliloquize, in the faintest of
undertones. The formless autumnal warble of the song sparrow is familiar
to every one. And in this connection I remember, and am not likely ever
to forget, a winter wren who favored me with what I thought the most
bewitching bit of vocalism to which I had ever listened. He was in the
bushes close at my side, in the Franconia Notch, and delivered his whole
song, with all its customary length, intricacy, and speed, in a tone--a
whisper, I may almost say--that ran along the very edge of silence. The
unexpected proximity of a stranger may have had something to do with his
conduct, as it often appears to have with the thrasher's; but, however
that may be, the cases are not parallel with that of the pine-wood
sparrow, inasmuch as the latter bird not merely sings under his breath
on special occasions, whether on account of the nearness of a listener
or for any other reason, but in his ordinary singing uses louder and
softer tones interchangeably, almost exactly as human singers and