The implications for conservation of a major taxonomic revision of the world’s birds

A recent comprehensive revision of the taxonomy that underpins the global IUCN Red List for birds led to an increase of 10.7% (over 1000 species) in the number of recognized bird species. We assessed the implications for conservation of this revision by (1) comparing extinction risk between newly recognized and unrevised species, (2) calculating the extent to which newly recognized species’ ranges are covered by Important Bird and Biodiversity Areas (IBAs) and protected areas, and (3) identifying new hotspots of extinction risk, where high numbers of newly recognized threatened species intersect areas of low protected area coverage. Unexpectedly, newly recognized species derived from taxonomic division (splitting) were on average significantly less threatened in terms of their IUCN global threat categories than species whose taxonomic status remained unchanged, despite their significantly smaller mean range size. Newly recognized species listed as globally threatened had higher average coverage of their ranges by IBAs and protected areas than their pre-revision ‘parents’, although 25 and 21 species had no coverage by IBAs or protected areas respectively. The absolute number of globally threatened species increased slightly overall, particularly in Java and the Philippines, already recognized as hotspots of extinction risk, and in eastern Amazonia, which emerged as a new hotspot of extinction risk. All three regions have low levels of protection and should be prioritized for expansion of the protected area network. Our results suggest that while major taxonomic revisions may lead to an increase in the absolute number of species requiring conservation attention, they do not necessarily lead to a rise in average extinction risk, a decrease in the coverage of species’ ranges by site-level conservation designations or a significant increase in the number of priority areas for conservation investment.