tion, they threaten a longer flight; but on getting high enough
to see the unbroken array of roofs, on every side they speedily grow
confused, and after a few shiftings of their course dive hurriedly into
the nearest tree. It was a mistake their stopping here in the first
place; but once here, there is nothing for it save to put up with the
discomforts of the situation till after sunset. Then, please heaven,
they will be off, praying never to find themselves again in such a
Babel.

That most of our smaller birds migrate by night is by this time too well
established to need corroboration; but if the student wishes to assure
himself of the fact at first hand, he may easily do it by one or two
seasons' observations in our Common,--or, I suppose, in any like
inclosure. And if he be blest with an ornithologically educated ear, he
may still further confirm his faith by standing on Beacon Hill in the
evening--as I myself have often done--and listening to the _chips_ of
warblers, or the _tseeps_ of sparrows, as these little wanderers, hour
after hour, pass through the darkness over the city. Why the birds
follow this plan, what advantages they gain or what perils they avoid by
making their flight nocturnal, is a question with which our inquisitive
friend will perhaps find greater difficulty. I should be glad, for one,
to hear his explanation.

As a rule, our visitors tarry with us for two or three days; at least I
have noticed that to be true in many cases where their numbers, or
size, or rarity made it possible to be reasonably certain when the
arrival and departure took place; and in so very limited a field it is
of course comparatively easy to keep track of the same individual during
his stay, and, so to speak, become acquainted with him. I remember with
interest several such acquaintanceships.

One of these was with a yellow-bellied woodpecker, the first I had ever
seen. He made his appearance one morning in October, along with a
company of chickadees and other birds, and at once took up his quarters
on a maple-tree near the Ether monument. I watched his movements for
some time, and at noon, happening to be in the same place again, found
him still there. And there he remained four days. I went to look at him
several times daily, and almost always found him either on the maple or
on a tulip tree a few yards distant. Without question the sweetness of
maple sap was known to _Sphyropicus varius_ long before our human
ancesto