Wild Ducks have a powerful, sustained, and rapid flight. With one stroke of the wing they raise themselves either from the land or water, and mount perpendicularly above the summits of the loftiest trees, when they take a more horizontal course, maintaining themselves at a great height, and making long journeys without rest. Triangular columns of them may sometimes be seen directing their unerring course towards their destination, the rustling of their wings being heard at considerable distances. The leading bird, which directs the course of the band, and which is thus exposed to the first resistance of the wind, from being foremost to cleave the air, soon becomes fatigued, when it falls back into the second rank, its place in the van being immediately taken by another (Fig. 87). Wild Ducks are extremely suspicious in their nature. When they want to settle down on any spot, or to go from one pool to another, they sweep round in concentric curves, descending and ascending again and again, until they have made a complete survey of their intended halting-place. The margins of fresh-water lakes, pools, and marshes are the principal localities frequented by the Wild Duck, so long as the frosts of winter do not prevent their obtaining the water-insects and aquatic weeds on which they feed. But when the frost has congealed the stagnant waters, they take themselves off into more temperate climates, invariably following the course of the rivers and running streams. When they return northward after the great thaw--that is, about the end of February--they keep in pairs, and disperse themselves in search of breeding-places among the rushes, reeds, and sedge-grasses, constructing a bulky nest of weeds, which is simply placed on the ground, and generally near to water. [Illustration: Fig. 87.--Flight of Wild Ducks.] Much elegance is not to be looked for in the nest of the Wild Duck. A favourite situation is a thickly-growing tuft of sedge, and they content themselves with plucking off a few of the blades, the ends of which they bend down so as to form a foundation, the surface being covered with a soft layer of down. Their nests are occasionally found at some distance from the water, amidst heath or broom, or even in the fork of a tree, the female having been known to take possession of a Magpie's or Crow's nest which had been abandoned. The Duck lays from five to ten eggs, and sometimes more; their colour varies, but is generally a dull greenish white. The female sits alone, and only leaves the nest to seek her food. When leaving her nest, she covers it up carefully with any rubbish at hand; on her return, the cunning creature alights a considerable distance from it, and glides through the grass, looking in every direction to see that she is not watched; if discovered, she will even feign lameness to induce pursuit, so that she may draw off intruders.