Page:Cassell's book of birds (IA cassellsbookofbi04breh).pdf/166

 (Casarca rutila).

the claws are weak; in the moderate-sized, narrow, and pointed wing the second quill is the longest; the short broad tail is composed of from fourteen to twenty feathers, and is either rounded or pointed at its extremity. The plumage, which is rich, smooth, and thickly interspersed with down, varies in colour according to the sex or age of the bird; that of the male is more or less brilliant, and that of the female of comparatively sombre hue. The members of this family, regarded generally, are to be met with in every climate; the number of species is, however, greater in warm than in cold latitudes, while on the contrary in northern regions individuals of the same species swarm in immense numbers. Ducks frequent both fresh and salt water, being sometimes met with on mountain lakes to a considerable elevation; at the approach of winter they migrate to southern latitudes, often in incalculable hosts. In the extent of their migrations some species emulate the Swallow itself, while others wander no further than is absolutely necessary in order to obtain food. These migrations are generally commenced at sunset; towards midnight the birds alight upon some expanse of water, and after resting for a few hours recommence their journey in the early morning. Their flight is conducted either in one long string or in a wedge-like phalanx. The power of locomotion displayed by these birds is very various; some species can walk upon dry ground almost as well as the Geese, while others waddle along with considerable difficulty. All are excellent swimmers, but they only dive exceptionally, and with considerable effort. Their flight is accomplished by rapid movements of their wings, and they are able to rise as easily from the surface of the water as from the ground. Ducks subsist upon both animal and vegetable food; some, however, prefer the former, while others confine themselves to the latter diet. They are for the most part monogamous, and generally associate during the breeding season in great numbers; a circumstance in which they differ remarkably from the Swans and Geese. Some build their nests in holes in the ground or in the