Let us take our way to some pond or lake, thick with duckweed and beloved of wild fowl, and we shall find a different state of affairs. We surprise a group of mallard ducks, which rush out from the overhanging bank and dive for safety among the sheltering green arrowheads. But their outspread wings are a mockery, the flight feathers showing as a mere fringe of quill sticks, which beat the water helplessly.
Another thing we notice. Where are the resplendent drakes? Have they flown elsewhere and left their mates to endure the dangers of moulting alone? Let us come here a week later and see what a transformation is taking place. When most birds moult it is for a period of several months, but these ducks have a partial fall moult which is of the greatest importance to them. When the wing feathers begin to loosen in their sockets an unfailing instinct leads these birds to seek out some secluded pond, where they patiently await the moult. The sprouting, blood-filled quills force out the old feathers, and the bird becomes a thing of the water, to swim and to dive, with no more power of flight than its pond companions, the turtles.
If, however, the drake should retain his iridescent head and snowy collar, some sharp-eyed danger would spy out his helplessness and death would swoop upon him. So for a time his bright feathers fall out and a quick makeshift disguise closes over him—the reed-hued browns and grays of his mate—and for a time the pair are hardly distinguishable. With the return of his power of flight comes renewed brightness, and the wild drake emerges from his seclusion on strong-feathered, whistling wings. All this we should miss, did we not seek him out at this season; otherwise the few weeks would pass and we should notice no change from summer to winter plumage, and attribute his temporary absence to a whim of wandering on distant feeding grounds.
Another glance at our goldfinch shows a curious sight. Mottled with spots and streaks, yellow alternating with greenish, he is an anomaly indeed, and in fact all of our birds which undergo a radical colour change will show remarkable combinations during the actual process.
It is during the gray days that the secret to a great problem may be looked for—the why of migration.
A young duck of the year, whose wings are at last strong and fit, waves them in ecstasy, vibrating from side to side and end to end of his natal pond. Then one day we follow his upward glances to where a thin, black arrow is throbbing southward, so high in the blue sky that the individual ducks are merged into a single long thread. The young bird, calling again and again, spurns the water with feet and wings, finally rising in a slowly ascending arc. Somewhere, miles to the southward, another segment approaches—touches—merges.
But what of our smaller birds? When the gray days begin to chill we may watch them hopping among the branches all day in their search for insects—a keener search now that so many of the more delicate flies and bugs have fallen chilled to the earth. Toward night the birds become more restless, feed less, wander aimlessly about, but, as we can tell by their chirps, remain near us until night has settled down. Then the irresistible maelstrom of migration instinct draws them upward,—upward,—climbing on fluttering wings, a mile or even higher into the thin air, and in company with thousands and tens of thousands they drift southward, sending vague notes down, but themselves invisible to us, save when now and then a tiny black mote floats across the face of the moon—an army of feathered mites, passing from tundra and spruce to bayou and palm.
In the morning, instead of the half-hearted warble of an insect eater, there sounds in our ears, like the ring of skates on ice, the metallic, whip-like chirp of a snowbird, confident of his winter’s seed feast.