The potential energy stored up in the small richly colored eggs of this northern sandpiper is almost beyond comprehension. The downy chicks, as soon as they are out of the shell, show wonderful activity. When they are but 30 minutes old, their apparently slight legs carry them over the ground with great rapidity. They know at birth how to hide among the hummocks and vegetation so as to defy the sharpest eyes. In three weeks they are awing and six weeks later they are off on their long journey to the south, crossing mighty mountain ridges, great stretches of land and of sea. According to W. H. Hudson (1920), the pectoral sandpiper arrives in the La Plata region, in southern South America, about the end of August, and he writes: Among these first comers there are some young birds, so immature, with threads of yellow down still adhering to the feathers of the head, and altogether weak in appearance, that one can scarcely credit the fact that so soon after being hatched they have actually performed the stupendous journey from the northern extremity of the North American continent to the Buenos-Ayrean pampas. _Plumages._--The young pectoral in down is a beauty and is distinctively colored. The forehead, back to the eyes, lores, sides of the head and neck, and the breast are from "cinnamon buff" to "cream buff," paling to white or grayish white on the throat and belly. There is a broad, black, median stripe from the crown to the bill, a narrow, black loral stripe, which is joined by another, still narrower, malar stripe under the eye, extending to the auriculars; below the ear is a dark-brown spot. In the center of the crown is a black spot, surrounded by a circle of buffy white dots; around this the crown is a mixture of black and "burnt sienna," bordered with buffy white, except in front; and around this border, or along each side of it, is a narrow stripe of blackish brown above the buffy superciliary stripe. The nape is grizzly brown, buff, and whitish. The back, wings, and thighs are variegated with black, "chestnut," and "burnt sienna," and decorated with small dots of buffy white in an irregular pattern. The juvenal plumage is much like that of the summer adult, except that the feathers of the mantle, scapulars, and the median and lesser wing coverts are edged with brighter colors, "tawny," "ochraceous-buff," and creamy white; and the breast is more buffy or yellowish. This plumage is apparently worn all through the fall and winter or until the first prenuptial molt in February and March, when the body plumage is renewed. At the first postnuptial molt, the next summer, the young bird becomes indistinguishable from the adult, having molted the entire plumage.