ed. I used to watch them in the oak groves of some Longwood
estates, but it was not till our second or third interview that I
discovered them to be the authors of a mystery over which I had been
exercising my wits in vain, a tree-frog's note in winter! One of their
amusements was to drum on the tin girdles of the shade trees; and
meanwhile they themselves afforded a pastime to the gray squirrels, who
were often to be seen creeping stealthily after them, as if they
imagined that _Melanerpes erythrocephalus_ might possibly be caught, if
only he were hunted long enough. I laughed at them; but, after all,
their amusing hallucination was nothing but the sportsman's instinct;
and life would soon lose its charm for most of us, sportsmen or not, if
we could no longer pursue the unattainable.

Probably my experience is not singular, but there are certain birds,
well known to be more or less abundant in this neighborhood, which for
some reason or other I have seldom, if ever, met. For example, of the
multitude of pine finches which now and then overrun Eastern
Massachusetts in winter I have never seen one, while on the other hand I
was once lucky enough to come upon a few of the very much smaller number
which pass the summer in Northern New Hampshire. This was in the White
Mountain Notch, first on Mount Willard and then near the Crawford House,
at which latter place they were feeding on the lawn and along the
railway track as familiarly as the goldfinches.

The shore larks, too, are no doubt common near Boston for a part of
every year; yet I found half a dozen five or six years ago in the marsh
beside a Back Bay street, and have seen none since. One of these stood
upon a pile of earth, singing to himself in an undertone, while the rest
were feeding in the grass. Whether the singer was playing sentinel, and
sounded an alarm, I was not sure, but all at once the flock started off,
as if on a single pair of wings.

Birds which elude the observer in this manner year after year only
render themselves all the more interesting. They are like other species
with which we deem ourselves well acquainted, but which suddenly appear
in some quite unlooked-for time or place. The long-expected and the
unexpected have both an especial charm. I have elsewhere avowed my
favoritism for the white-throated sparrow; but I was never more
delighted to see him than on one Christmas afternoon. I was walking in a
back road, not far from the city, when I de