The male suddenly gets up from the snow-clad ground, and producing the most beautiful flutelike notes, following an oblique line with rapid wing strokes, mounts to an enormous height often so high that he can not be followed with the naked eye. Up here in the clear frosty air he flies around in large circles on quivering wings and his melodious far-sounding notes are heard far and wide over the country, bringing joy to other birds of his own kin. The song sounds now more distant, now nearer, when three or four males are singing at the same time. Now and then the bird slides slowly downwards on stiff wings with the tail feathers spread; then again he makes himself invisible in the higher regions of the air, mounting on wings quivering even faster than before. Only now and then the observer--guided by the continuing song--succeeds for a moment in discerning the bird at a certain attitude of flight, when the strong sunlight falls upon his golden-colored breast or light wings. Gradually, as in increasing excitement he executes the convulsive vibrations of his wings, his song changes to single deeper notes--following quickly after each other--at last to die out while the bird at the same time drops to the earth on stiff wings strongly bent upward. This fine pairing song may be heard for more than a month everywhere at the breeding places, and it wonderfully enlivens this generally so desolate and silent nature. The song will at certain stages remind of the fluting call note of the curlew (_Numenius arquatus_), but it varies so much with the temper of the bird that it can hardly be expressed or compared with anything else. _Nesting._--The nesting habits of the knot long remained unknown; Arctic explorers were baffled in their attempts to find the nest; and the eggs were among the greatest desiderata of collectors. This is not to be wondered at, however, when we consider the remoteness of its far northern breeding grounds, its choice of its nesting sites on high inland plains, its widely scattered nests, and its habit of sitting very closely on its eggs and not returning to them after flushing. Col. H. W. Feilden (1879) writes: Night after night I passed out on the hills trying to find the nest of the knot. Not a day passed without my seeing them feeding in small flocks; but they were very wild, rising with shrill cries when one approached within a quarter of a mile of the mud flats on which they were feeding. It is very extraordinary, considering the hundreds of miles traversed by myself and my companions--all of us on the lookout for this bird's eggs, and several of us experienced bird's-nesters--that we found no trace of its breeding until the young in down were discovered.