Some species in the world are endemic to one area. Endemic (in animals) means native and restricted to one place. For example, kangaroos are endemic to Australia. They are native to Australia and are found nowhere else in the world. Certain families of birds are endemic to specific zoogeographic realms. Here is an incomplete list of bird families and the regions they are endemic to.

Neotropical – Rhamphastidae (toucans); Tinamidae (tinamous)
Ethiopian – Struthionidae (ostrich); Musophagidae (turacos)
Oriental – Irenidae and leafbirds
Australasian – Dromaiidae (emu); Cacatuidae (cockatoos)

There are no bird families endemic to either the Nearctic or the Palearctic regions, but some birds are endemic to the Holarctic realm, which is the Nearctic and the Palearctic combined. These families include Gaviidae (loons); Tetraonidae (grouse) and Alcidae (murres, puffins & auks).