But the nighthawks which soar and boom above our city streets, whence come they? Do they make daily pilgrimages from distant woods? The city furnishes no forest floor on which they may lay their eggs. Let us seek a wide expanse of flat roof, high above the noisy, crowded streets. Let it be one of those tar and pebble affairs, so unpleasant to walk upon, but so efficient in shedding water. If we are fortunate, as we walk slowly across the roof, a something, like a brownish bit of wind-blown rubbish, will roll and tumble ahead of us. It is a bird with a broken wing, we say. How did it ever get up here? We hasten forward to pick it up, when, with a last desperate flutter, it topples off the edge of the roof; but instead of falling helplessly to the street, the bird swings out above the house-tops, on the white-barred pinions of a nighthawk. Now mark the place where first we observed the bird, and approach it carefully, crawling on hands and knees. Otherwise we will very probably crush the two mottled bits of shell, so exactly like pebbles in external appearance, but sheltering two little warm, beating hearts. Soon the shells will crack, and the young nighthawks will emerge,--tiny fluffs,--in colour the very essence of the scattered pebbles.
In the autumn they will all pass southward to the far distant tropics, and when spring again awakens, the instinct of migration will lead them, not to some mottled carpet of moss and rocks deep in the woods, but to the tarred roof of a house in the very heart of a great city.
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Migration is over, and the great influx of birds which last month filled every tree and bush is now distributed over field and wood, from our dooryard and lintel vine to the furthermost limits of northern exploration; birds, perhaps, having discovered the pole long years ago. Now every feather and plume is at its brightest and full development; for must not the fastidious females be sought and won?
And now the great struggle of the year is at hand, the supreme moment for which thousands of throats have been vibrating with whispered rehearsals of trills and songs, and for which the dangers that threaten the acquisition of bright colours and long, inconvenient plumes and ornaments have been patiently undergone. Now, if all goes well and his song is clear, if his crest and gorgeous splashes of tints and shades are fresh and shining with the gloss of health, then the feathered lover may hope, indeed, that the little brown mate may look with favour upon dance, song, or antic--and the home is become a reality. In some instances this home is for only one short season, when the two part, probably forever; but in other cases the choice is for life.