"And when do they go away again ?" "The great bird procession begins the first of March with Bluebirds, Robins, Redwings, and Meadowlarks, but it is the first of June before the latest comers, the little Marsh Wrens, are settled.

Then in autumn, from September until the first snows of December fall, the procession flutters back south again, one by one or in great flocks, dropping away like falling leaves in the forest, and the birds that we see later are likely to be Citizens.
"The early Robin may have a second brood and the Hummingbird eggs in her nest, before the Marsh Wrens have even been seen.
"In the Southern States the birds arrive and build sooner than in the Northern.

A cold spring may delay the on-coming migration, or a warm autumn retard the return movement.

But as you study birds you will soon see that each one has his own place in the procession, and usually keeps it.

Year by year this vast procession goes on in the air, back and forth, night and day, like the ceaseless ebb and flow of the tides at sea.