ing flies by
the way, and crying _peent-peent_, the acrobat climbs until I look a mere
lump on the roof; then ceasing his whimpering _peent_, he turns on bowed
wings and falls--shoots roofward with fearful speed. The chimneys! Quick!

Quick he is. Just short of the roofs the taut wings flash a reverse, there
is a lightning swoop, a startling hollow wind-sound, and the rushing bird
is beating skyward again, hawking deliberately as before, and uttering
again his peevish nasal cry.

This single note, the only call he has besides a few squeaks, is far from
a song; farther still is the empty-barrel-bung-hole sound made by the air
in the rushing wings as the bird swoops in his fall. The night-hawk, alias
"bull-bat," does not sing. What a name bull-bat would be for a singing
bird! But a "voice" was never intended for the creature. Voice, beak,
legs, head--everything but wings and maw was sacrificed for a mouth. What
a mouth! The bird can almost swallow himself. Such a cleft in the head
could never mean a song; it could never be utilized for anything but a
fly-trap.

We have use for fly-traps. We need some birds just to sit around, look
pretty, and warble. We will pay them for it in cherries or in whatever
they ask. But there is also a great need for birds that kill insects. And
first among these are the night-hawks. They seem to have been designed for
this sole purpose. Their end is to kill insects. They are more like
machines than any other birds I know. The enormous mouth feeds an enormous
stomach, and this, like a fire-box, makes the power that works the
enormous wings. From a single maw have been taken eighteen hundred winged
ants, to say nothing of the smaller fry that could not be identified and
counted.

But if he never caught an ant, never one of the fifth-story mosquitos that
live and bite till Christmas, how greatly still my sky would need him! His
flight is song enough. His cry and eery thunder are the very voice of the
summer twilight to me. And as I watch him coasting in the evening dusk,
that twilight often falls--over the roofs, as it used to fall for me over
the fields and the quiet hollow woods.

There is always an English sparrow on my roof--which does not particularly
commend the roof to bird-lovers, I know. I often wish the sparrow an
entirely different bird, but I never wish him entirely away from the roof.
When there is no other defense for him, I fall back upon his being a
bird. Any kind of a bird i