Brazil has one of the richest bird diversities in the world. The avifauna of Brazil include a total of 1825 confirmed species of which 238 are endemic. Five have been introduced by humans, 78 are rare or vagrants, and four are extinct or extirpated. An additional 21 species are hypothetical (see below). Brazil hosts about 60% of the bird species recorded for all of South America. These numbers are still increasing almost every year, due to new occurrences, new species being described, or splits of existing species. About 10% of the bird species found in Brazil are, nonetheless, threatened.