There are between 8,700 and 9,600 living species of birds today. These range in size from tiny (such as hummingbirds) to huge (such as ostriches and condors). Bird species are divided into 2 superfamilies, the Paleognathae or “old jaws,” and the Neognathae or “new jaws.”The Paleognathae family includes 5 orders, the Tinamiformes, the Rheiformes, the Casuariiformes, the Apterygiformes, and the Struthioniformes. The Tinamiformes order is comprised of some 45 species, most in South and Central America. Members of the other orders are flightless and very large. Collectively, they are often known as ratites and include the ostriches, the emus and cassowaries, the kiwis, and the rheas.The superfamily Neognathae is huge and includes most of the bird species that are alive today. While over the millennia, individuals from a large number of these species have been kept as pets at one time or another and some have been domesticated, only a relatively small number of species have been widely kept as companion animals. With some exceptions (such as swans and peacocks) these pet species have been birds that have adapted to caged life and have some specific appeal such as very colorful feathers, a pleasing range of calls, the ability to mimic human speech, or engaging behaviors.