Birds have been arranged in groups and families in various ways by different Naturalists, but the most satisfactory classification is the division into six great families. First, the Raptores, or Birds of Prey; second, the Natatores, or Swimming Birds; third, the Grallatores, or Wading Birds; fourth, the Scransores, or Climbing Birds; fifth, the Gallinaceae, or Domestic Birds; sixth, the Passerines, or the Sparrow Family. BIRDS OF PREY. The numerous Birds classified as Raptores, or Birds of Prey, are divided into two great families—the Owls or Nocturnal Birds of Prey, who hunt and kill their prey during the night; and the Diurnal Birds of Prey, including the Falcons, Eagles and the Vultures, who seek their food during the day. All the different Birds belonging to this order are characterized by a strong, hooked and sharp-edged bill, strong legs covered with feathers, four toes, three in front and one behind, which are usually very flexible, and provided with strong talons. As their name indicates, they live by plunder and blood-shedding. They correspond in the class of Birds with the Carnivora among Mammals. Like them, they live on animals, either dead or living; like them, too, they possess the strength and cunning which are necessary to secure their victims. The Birds of Prey do not possess any of the graces and power of song which characterize other races of Birds. Their only utterance consists of harsh cries or strange and plaintive sounds, and it is very seldom that their plumage is gay or attractive. Destruction is the sole object of their existence, and they are the terror of the rest of the feathered creation. They are found over the whole surface of the globe. The larger species inhabit lofty mountains, or seek a hiding place in solitary cliffs. THE OWL FAMILY. [Illustration: OWLS.] The Owls represent the nocturnal Birds of Prey. They are distinguished by large staring eyes directed straight in front, and surrounded by a circle of slender and stiff feathers, which by their radiation around the face form a nearly complete disc. They have short strong bills and sharp claws for seizing their prey. With the exception of the Barn Owl, all these nocturnal Birds of Prey lay eggs of spherical shape. They live in couples, only assembling in flocks at the time of migrating to a warmer climate. They do not build any nests but deposit their eggs in the cavities in old trunks of trees or ruined habitations. None of these Birds come out of their roosting places during the day, unless they are forced to do so. For brief and simple classification the Owl family is usually divided into two groups—the Horned Owls and the Hornless Owls. THE HORNED OWLS.