Not withstanding the fact that the American Vultures quite closely resemble the Old World Vultures in general appearance and habits, there are certain marked differences which well entitle them to be ranked as a separate group. Among other things they have the relatively short hind toe inserted above the level of the others, lengthened, slightly hooked bills, and perforated nostrils, that is, with an opening between them inside the bill. The head is entirely naked or else partially covered with down, and the feet are provided with blunt claws which are wholly unfitted for grasping. They feed largely, though not exclusively, on decaying animal matter, and have the exceedingly offensive habit of vomiting the foul contents of the stomach when captured or surprised. They build no nest, the eggs from one to three, usually two in number being placed in a hollow tree or log or in a cave or crevice in the rocks, or even on the bare ground. The young are fed by regurgitation, or the emptying of the con-tents of the stomach into the mouths of the young.
The American Vultures are all large, though somewhat sluggish, birds with great powerful wings and are past masters in the art of flying. On this point Bendire says of the California Vulture : “Its flight is graceful beyond comparison as it sails majestically overhead in gradually contracting or expanding circles, now gently falling with the wind and again rising easily against it, without a perceptible motion of its pinions. While on the wing it looks more than the peer of any of our birds, the Golden Eagle not excepted.” The American Vultures are distributed into five genera and some nine or ten species, of which three genera and the same number of species are represented in the United States. With the exception of the northern portion of their range, they are mainly resident throughout the year wherever found.