These regions are not as distinctive as this listing would imply, for there are always groups of animals whose ranges extend through more than one region. In general, however, each of these areas has a distinct fauna with enough elements peculiar to it to warrant its listing as a zoogeographical region.
Most distinctive of all regions is the Australian which includes Australia and New Guinea. These areas have been isolated from other regions for so long that they have a distinctive fauna. Here are found the monotremes (egg-laying mammals) such as the duckbill; a large and varied assemblage of marsupials; and unusual birds like the emus, lyrebirds, honey eaters (honeysuckers), cockatoos, and the remarkable birds of paradise. The Australian lungfish, distinctive tortoises, and many unique invertebrates also belong to this region.
The Oceanian region includes New Zealand, Antarctica, and the oceanic islands of the Pacific. In New Zealand is found the curious lizardlike Sphenodon, only survivor of an ancient group, and the kiwi bird. The oceanic islands of this region are characterized more by the lack of many groups of animals than by the presence of particular ones. There are, however, many distinctive shore fishes about the islands.
The Neotropical region, consisting of South America, has sloths, anteaters, armadillos, monkeys with prehensile tails, vampire bats, and marmosets. Among the unusual birds are the rheas, toucans, hoatzins, guans, and cassowaries. Many distinctive snakes are found, including boas, anacondas, and tropical pit vipers.
The Oriental subregion of the Paleotropical region includes southern India, southeast Asia, and the Malay Archipelago. It has many distinctive birds including pheasants, babbling thrushes, and barbets. Among the mammals are the Indian elephants, some lemurs, tigers, orangutans, gibbons, and some antelopes.
The Ethiopian subregion of the Paleotropical is formed of Africa south of the Sahara. It contains the aardvark, chimpanzee, gorilla, lion, and many kinds of antelopes. Among the birds are the ostrich and secretary bird. Close to Africa is the Malagasy subregion, consisting of the island of Madagascar and neighboring islands of the Indian Ocean. Madagascar has crayfishes that are lacking in Africa. It also has many different types of lemurs, including the aye-aye, and such unusual birds as the extinct gigantic Aepyornis, an ostrich-like bird that may have survived until historic times.
The Palearctic subregion of the Holarctic region consists of Europe, most of Asia, and Africa north of the Sahara. The Nearctic subregion consists of Canada, the United States, and a small portion of Mexico. These two subregions have many faunal elements in common, including distinctive deer, bears, wolves, rodents, and ungulates.
The Caribbean is a transitional subregion between the Holarctic and Neotropical regions. This area of Central America, Mexico, and the Caribbean islands possesses fauna derived from both the other regions as well as some distinctive features. The Arctic subregion is characterized by severe climatic conditions and various circumpolar mammals.
While each region has its unique faunal elements, it also shares other elements with different regions. The boundaries between them are at best hazy and ill defined. Nowhere is the tenuous nature of these boundaries more evident than in the various lines drawn to separate the Australian and Papuan subregions from the Oriental subregion.
