The proportion of bird species in each IUCN Red List category as of 2020

Using the criteria and categories of the IUCN Red List (IUCN 2001), BirdLife International’s 2020 assessment of the world's birds concluded that 1,481 species (13.5% of extant data sufficient species, or one in eight) are globally threatened with extinction (see figure). These comprise 223 species classed as Critically Endangered (meaning that they are considered to be facing an extremely high risk of extinction), 460 species assessed as Endangered (very high risk of extinction) and 798 listed as Vulnerable (high risk of extinction). An additional 1,001 species are considered Near Threatened because they are assessed as close to qualifying as globally threatened. Hence a total of 2,482 species or just under a quarter of all the world’s birds are treated as global conservation priorities. Only 52 species (0.5% of the total) are considered insufficiently known to be able to assess their threat status, and so are classified as Data Deficient.

Threatened species are not evenly distributed among bird families. There are particularly high proportions of threatened species among albatrosses (68%), cranes (67%), parrots (28%), pheasants (21%) and pigeons (20%). Furthermore, families and genera with few species have disproportionately high numbers of threatened species (Purvis et al. 2000). Even allowing for these taxonomic effects, larger-bodied species and those with low reproductive rates (owing to small clutch sizes) are also more likely to be threatened (Bennett and Owens 1997).