Global trends in bird species survival indicator: data sources and methods, chapter 2

2. Description and rationale of the Global Trends in Bird Species Survival Indicator

2.1 Description

The Red List Index (RLI) shows trends in aggregate extinction risk over time (i.e., overall improvement or deterioration in threat status) for bird species on the International Union for Conservation of Nature (IUCN) Red List. The index is derived from the proportion of species changing category due to genuine biological status changes from one assessment to the next, and acts as an indicator of the changing status of global biodiversity. A downward trend in the RLI indicates that the set of species assessed has moved to a higher level of extinction risk.^{Footnote [1]}

2.2 Rationale

World biodiversity continues to decline in the face of increasing pressures.^{Footnote [2]} In 2002, parties to the Convention on Biological Diversity (CBD) committed to significantly reduce the rate of biodiversity loss by 2010 and this target was included in the United Nations Millennium Development Goals. The IUCN RLI was developed in 2004 to serve as an indicator of progress toward achieving the 2010 goal and monitor the changing status of the world’s biodiversity. In 2010, the CBD parties adopted a new suite of targets for 2020, including the aim by 2020 of preventing the extinction of known threatened species and improving their conservation status, for which the RLI will be used to measure progress. The RLI is based on the IUCN Red List of Threatened Species, recognized as the most objective and authoritative system for classifying species at risk of extinction.^{Footnote [3],Footnote [4]}

2.3 Recent changes to this indicator

This report reflects new knowledge, revisions to status assessments and changes in taxonomic status since 2008. BirdLife International provides detailed explanations of rank changes.