These Ptarmigans prefer the shelter of birch or willow trees, and where such abound are frequently met with in very large numbers, one pair living close to another, but each holding its own small domain (usually measuring about fifteen paces) with the utmost intrepidity against all intruders; no sooner, however, is the breeding season over than the various families unite into large flocks, and wander over the country to a considerable distance. In disposition this species is lively, and its movements generally restless and rapid, its broad, thickly-feathered feet enabling it to run with equal facility over fresh snow or unsafe moss-covered earth. Whilst in motion the head and tail are usually held down; but when the bird is quite secure from danger, the body is kept much elongated, and the head boldly raised erect. The flight is graceful and light, that of the male accompanied by a loud resonant note as he is about to descend, but the female utters no sound when on the wing. During very severe seasons, or when an enemy is at hand, the Willow Ptarmigan frequently takes refuge in the snow for warmth or shelter; and in very sharp wind, or biting frost, it is not uncommon to see a whole flock snugly buried in a snow-bed, close to each other, with only their heads protruding, to enable them to detect the first sign of danger, in evading which they exhibit a most wonderful instinct. Their food consists of leaves, buds, blossoms, berries, and various kinds of insects; grain of all kinds they also devour. The nest of this species is concealed with great skill in some retired nook, and slightly lined with grass, earth, and feathers. The small pear-shaped eggs are laid at the end of May or beginning of June; they are from twelve to sixteen in number, and have a yellowish shell, thickly covered with reddish-brown dots and streaks. No sooner are the young capable of walking than they are at once led forth to seek their food upon the neighbouring marshes and bogs, as the insects and larvæ of which such localities afford a rich supply are particularly acceptable to the delicate little family. Throughout the whole of the breeding season, many and fierce encounters take place between the male birds, and from ten o'clock in the evening till early morning their loud calls may be heard challenging each other to a trial of strength, which usually continues until the females gently warn their pugnacious partners that it is time to retire to rest. THE ALPINE OR GREY PTARMIGAN.