n out
six or eight times without the slightest alteration. Such freaks as
these, however, are different from the linnet's _Mary Ware_, inasmuch as
they are certainly the idiosyncrasies of single birds, not a part of the
artistic proficiency of the species as a whole.

During this month I was lucky enough to close a little question which I
had been holding open for a number of years concerning our very common
and familiar black-throated green warbler. This species, as is well
known, has two perfectly well-defined tunes of about equal length,
entirely distinct from each other. My uncertainty had been as to whether
the two are ever used by the same individual. I had listened a good many
times, first and last, in hopes to settle the point, but hitherto
without success. Now, however, a bird, while under my eye, delivered
both songs, and then went on to give further proof of his versatility by
repeating one of them _minus_ the final note. This abbreviation, by the
way, is not very infrequent with _Dendroeca virens_; and he has still
another variation, which I hear once in a while every season, consisting
of a grace note introduced in the middle of the measure, in such a
connection as to form what in musical language is denominated a turn. At
my first hearing of this I looked upon it as the private property of the
bird to whom I was listening,--an improvement which he had accidentally
hit upon. But it is clearly more than that; for besides hearing it in
different seasons, I have noticed it in places a good distance apart.
Perhaps, after the lapse of ten thousand years, more or less, the whole
tribe of black-throated greens will have adopted it; and then, when some
ornithologist chances to fall in with an old-fashioned specimen who
still clings to the plain song as we now commonly hear it, he will fancy
_that_ to be the very latest modern improvement, and proceed forthwith
to enlighten the scientific world with a description of the novelty.

Hardly any incident of the month interested me more than a discovery (I
must call it such, although I am almost ashamed to allude to it at all)
which I made about the black-capped titmouse. For several mornings in
succession I was greeted on waking by the trisyllabic minor whistle of a
chickadee, who piped again and again not far from my window. There could
be little doubt about its being the bird that I knew to be excavating a
building site in one of our apple-trees; but I was usually not