Most of them prefer plains to mountainous districts; nevertheless, certain species are to be met with at considerable altitudes, both in the Himalayas and the Andes. They walk extremely well, and though in swimming they are neither so graceful as the Swans nor as active as the Ducks, they row themselves along with ease and facility; on an emergency many of them will dive to a considerable depth, and the power and endurance of their flight is remarkable. When flying in companies, they always arrange themselves in a regular V-shaped phalanx, the form of which appears to be of importance; neither is it difficult to understand why they so persistently adopt the same arrangement, as it is evident that such a disposition is the only one that would enable every individual of the numerous party to have a free and unobstructed range of vision, and, moreover, it possibly facilitates their passage through the air, at all events it affords free scope for the use of their wings, which otherwise, from their crowding together, would be seriously interfered with. Very generally a flight of Wild Geese will be seen to press onward with unbroken ranks until they are quite lost in the distance; occasionally, however, they will, as it were, with one consent relax their speed, break up their phalanx, and for a short space become confusedly mixed together. Soon, however, a leader again places himself at their head; his followers resume their ranks, and the whole body moves forward in precisely the same order as before. Their flight is accompanied by a loud rushing noise, caused by the powerful strokes of their wings, and the rising or setting down of a flock presents a very bustling scene. When walking on level ground, the Geese keep the fore part of the body slightly elevated, with their neck straight or somewhat bent. Their steps are short and quick, and upon occasions many species can run with considerable speed. While swimming, the breast is deeply immersed, while the tail, on the contrary, is raised above the surface of the water. Their voice varies with the species; most of them express their anger by loud and prolonged hissing, some cackle, while others, like the Singing Swans, produce loud resonant notes that can be heard at a great distance.