The ornithology of tropical America exceeds in splendor that of any other region of the globe. Among the principal birds of prey are several species of eagle, including the large white-headed eagle of the United States, with vultures, hawks, kites, and owls. South America, however, possesses the largest of the vulture tribe--the gigantic condor of the Andes, which is confined to the higher peaks of those mountains, bordering on the limits of the snowy region. This is one of the most powerful and rapacious of birds, and commits numerous ravages among the cattle, deer, and other animals. The American ostrich, or emu, which dwells in the pampas of that region, is also distinguished by its size. The turkey is American, and is the only one of the domestic poultry that has been derived from the New World.[9] The toucans, distinguished by their enormous bills, are peculiar to America. The humming-birds are peculiar to the western continent, and in the tropical regions of America various birds of the most glittering plumage, together with numberless fire-flies, lend an almost magical charm to the aspect of nature. The range of the humming-birds extends over the whole continent to the southward of the 42d parallel (north lat.) and stretches upon the western side of North America as high as the parallel of 60°--an evidence of the superior warmth which distinguishes that side of the American continent. Both reptiles and insects are abundant in the New World, which, owing to its excessive moisture and dense vegetation, is peculiarly suited to the development of these departments of the natural kingdom. Venomous serpents are more numerous in tropical America than in any other part of the globe. The rattlesnake occurs in both divisions of the continent, within the parallels of 44° to the northward and of 30° to the south of the equator; the huge boa-constrictor, the largest of the serpent tribe, and the terror even of the natives, dwells in the marshes and swamps of South America. Huge caymans, iguanas, and other lizards, with numberless alligators and water-snakes, abound in the rivers and temporary lagoons of the same region. Australia possesses a zoology which is more distinctive than that of any other part of the world. Its native insects, reptiles, birds, and land animals are all strikingly different from those of other regions. The difference is greatest (or, at any rate, most obvious to ordinary observation) in the case of its land animals. Two-thirds of the Australian Mammalia belong to the marsupial order, and the kangaroo, the largest member of that family, surpasses in size any other of its indigenous quadrupeds. The Quadrumana, pachyderms, and ruminants are altogether unrepresented, nor are there any of the larger carnivora, the native dog (already verging on extinction) being the chief among them. In the present day large numbers of the Australian population are employed in rearing the domestic cattle of Europe.