Birds
Birds are feathered, winged, bipedal, warm-blooded, egg-laying, vertebrate animals. All modern birds lie within the Class Aves that includes 142 families, or over 9000 species of birds. The family designation is usually indicated by ending in -dae. Birds occupy all continents and habitats. They communicate using primarily visual and auditory signals. Ninety-five percent of bird species are socially monogamous. Some species, particularly songbirds and parrots, are popular as pets.
