On collecting Systematics Theme Birds on Stamps Systematics Species names A bird species is not always and forever a bird species. Scientists gather new information - and now and then one species becomes two species or two species are lumped to become one species.
Scientists disagree on lumpings and splittings.
As a result, lists of bird species may consist of from 9200 to 10100 species of birds in the world. Another consequence of new information is that the zoological, latin, name of a bird changes when the bird is considered to belong to another genus than before. Another exciting thing, not so much of consequence for birds on stamps, is the discovery of birds new to science. There are three major world lists available. A Checklist, 5th edition.