INSESSO'RES (Lat. perchers), or PERCHING BIRDS, an order of birds called passerine (sparrow-like) birds by Cuvier. In respect of the number of species which it contains, it is by far tire largest order of the whole class of birds. Cuvier says. " Its character seems at first sight purely negative, for it embraces all those birds which are neither swimmers, waders, climbers, rapacious, nor gallinaceous. Nevertheless, by comparing them, a very great mutual resemblance of .structure becomes perceptible." A principle characteristic is found in the structute of the feet, which are particularly adapted for perching on the branches of trees, and have three toes before and one behind, the hind toe on the same level with the others. The legs are neither very long nor very strong; nor are the claws in general very long or very sharp. The wings are often long, and the power of flight very considerable, but this is not always the case. The neck is not long. The bill exhibits many varieties in length, thickness, etc., being very short and thick in some, very slender in others, but never exhibits the characteristic peculiarities of the accipitrine beak, although there is an approach to them in the shrikes, which are a connecting link between the two orders. The insessores with short strong beaks are
principally granivorous, those with slender beaks insectivorous; but very many adapt themselves almost indifferently to both kinds of food. Some feed on pulpy fruits; some on vegetable juices; some chiefly on carrion. The stomach is a muscular gizzard. To the order insessores belongs the singing birds, and throughout the whole order a vari ously complicated structure of the lower larynx prevails. The insessores pair, but the attachment of the sexes in most of them seems to endure only for a single season. They generally build interwoven nests, and lay numerous eggs. The young are always naked and blind on coming forth from the egg.—The insessores are divided into four great tribes or sections, thortirostref, conirostres, tenui-rostres, and fissirostres. See these heads.