The Red List Index for the birds in different species groups for 1988–2012

Red List Index (RLI) of species survival for bird species in different species groups (n = 309 non-Data Deficient raptors, 830 waterbirds, 304 pigeons, 288 gamebirds, 356 parrots and 191 pelagic seabirds), showing the proportion of species expected to remain extant in the near future without additional conservation action. Source: Analysis of data held in BirdLife and IUCN’s Species Information Service (2013).

Some species-groups have been impacted particularly seriously by human activities and have an exceptionally high proportion of species listed as globally threatened. The Red List Index (RLI; Butchart et al. 2004, 2005, 2007) can be disaggregated to show trends for species in different families that are of particular conservation interest. This shows that pelagic seabirds (those using the open seas) have been impacted particularly seriously by human activities, being substantially more threatened on average (with lower RLI values) and deteriorating in status fastest over the last two decades. This is closely linked to the expansion of commercial longline fisheries, which causes incidental mortality of albatrosses and other seabirds, combined with the impacts of invasive alien species at seabird nesting colonies.

Interpreting the RLI
An RLI value of 1.0 equates to all species being categorised as Least Concern, and hence that none are expected to go extinct in the near future. An RLI value of zero indicates that all species have gone Extinct.