Only the water ouzel, winter after winter, seems not to notice the hardships of the season. Lord of his small world of open water, he sings in February, wading and swimming his diminished stream to find a never-failing supply of water insects and small fish. It is a voice of spring—glad, wild, continual as the moving water—an incongruous song in this winter-shrouded land. But with the growing stature of the sun, the grip of winter softens. The firs and spruce send their loads of snow sliding to the ground. Streams begin to sing again and soon the lakes increase, the booming of splitting ice breaking the silence of the valleys. Avalanches thunder down the steeper slopes, carrying trees to the swollen streams. Rivers hiss and rage, speeding the debris along. A spring that comes too suddenly will bring flood to lower elevations. Snow geese thread through the valleys, and ground squirrels tunnel up through snow to find invasions of birds returning from the south. Soon the three-petaled wakerobins appear, chasing the snowline up the ridges. Glacier lilies and Calypso orchids are next, and with the shooting stars spring arrives. The melting snow releases a new group of animals to populate the winter-thinned land. Up come chipmunks. Bears reappear. Young red squirrels, helpless and blind, squirm in their nest holes. Hidden dens rustle with pups and kits. Soon warm days will bring them out and the business of learning to cope with their world will begin. All life responds irresistibly to the growing strength of the Sun. Cottonwood, willow, and maple come into flower and unfold new leaves; green needle clusters spot the limbs of larches that in winter had seemed lifeless snags among the other conifers. Beneath the soil of prairie, meadow, and forest, in the mud of lakes and ponds, other life stirs; armies of insects, spiders, crustaceans, amphibians, and fish will strive to complete their life cycles against the formidable odds of a predatory world. Spring reaches higher up the mountains, the lowlands passing into summer. Wapiti and mountain sheep follow the rising tide of succulent browse up to the high meadows. In forest, grove, and meadow and along the stream new fledglings appear—thrush, vireo, hummingbird, waxwing, harlequin duck, bluebird, osprey, and flicker—as holes, nests, and cavities brim with begging mouths. In the alpine meadows, where snow overlaps the spring and winter follows hard behind the summer, the growing season is short and the climate unstable. Sensing the stronger light, flowers push up impatiently through the snow and hasten into bloom. Pikas and marmots scurry and sunbathe among the rocks of scree slopes. Summer matures in ripening huckleberries, and the bears that grazed the spring grasses now gorge themselves fat. Dry days of August bring probing lightning, threatening the forests with fire.