Although the mountain-tops have only a few resident birds, they have numerous summer bird builders and sojourners. Many birds nest in these heights instead of going to similar conditions in the great Arctic Circle nursery. Thus most birds met with in the heights during the summer season are the migratory ones. Among the summer residents are the American pipit, the white-crowned sparrow, and the gray-headed junco, the latter occasionally raising two broods in a summer. Here, too, in autumn come flocks of robins and other birds for late berries before starting southward. The golden eagle may soar above the peaks during all the seasons, but he can hardly be classed as a resident, for much of the winter he spends in the lower slopes of the mountains. Early in the spring he appears in the high places and nests among the crags, occasionally twelve thousand feet above sea-level. The young eaglets are fed in part upon spring lamb from the near-by wild flocks. One day, while in a bleak upland above the timber-line, I paused by a berg-filled lake, a miniature Arctic Ocean, with barren rock-bound shores. A partly snow-piled, half-frozen moor stretched away into an arctic distance. Everything was silent. Near by a flock of ptarmigan fed upon the buds of a clump of arctic willow that was dwarfed almost out of existence. I felt as though in the polar world. "Here is the environment of the Eskimo," I discoursed to myself. "He ought to be found in this kind of place. Here are icebergs, frozen tundras, white ptarmigan, dwarf willows, treeless distances. If arctic plants were transported down here on the Big Ice Floe, surely some Eskimo must have been swept along. Why didn't he stay? The climate was better, but perhaps he missed his blubber and sea food, and there was no midnight sun and the nights were extremely short. The pale and infrequent aurora borealis must have reminded him of better nights, if not better days. Anyway, even for the Eskimo, there is no place like home, even though it be in a domed and dingy ice house amid the eternal snows and beneath the wonderful sky of northern lights." [Illustration: AT THE EDGE OF THE ARCTIC-ALPINE LIFE ZONE IN THE SAN JUAN MOUNTAINS]