Global trends in bird species survival indicator: data sources and methods, chapter 3

3. Data

3.1 Data source

Data for this indicator come from the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. The Red List categorizes species in terms of their risk of extinction, as determined by assessment against a set of standardized, quantitative criteria. Information on species' population size, population trends, and geographic range are applied against these criteria to categorize species into one of nine Red List Categories: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient or Not Evaluated. Detailed definitions and guidance on the IUCN Red List classification and criteria have been developed.

Most assessments included in the Red List are carried out by members of the IUCN Species Survival Commission (SSC) Specialist Groups, IUCN Red List Partner organizations, appointed Red List Authorities or participants of Global Biodiversity Assessment workshops, a joint initiative of the IUCN/SSC and the Center for Applied Biodiversity Science at Conservation International. For more information on how assessments are conducted, see the IUCN Assessment Process website.

BirdLife International is the Red List Authority for birds and hence provides all the assessments for birds on the IUCN Red List. BirdLife International maintains all assessments and associated documentation in the Species Information System, which is co-managed with IUCN.

Terrestrial biogeographic realms are provided by the World Wildlife Federation (Olson et al., 2001). A generalization that includes ocean areas was provided by the United Nations Environment Programme - World Conservation Monitoring Centre (UNEP-WCMC) for visualization purposes.

3.2 Spatial coverage

The IUCN Red List is a global-level assessment. The Red List Index (RLI) is calculated for all bird species, and can also be disaggregated to show trends for species in different biogeographic realms, ecosystems, and taxonomic groups.^{Footnote [1]}

3.3 Temporal coverage

The first global assessment of bird species was completed in 1988 with comprehensive assessments conducted in 1994, 2000, 2004, 2008 and 2012. The first RLI was calculated in 2004, using data on bird species for the period 1988 to 2004. The RLI has been periodically updated since then, most recently in 2012.

3.4 Data completeness

All bird species assigned to threat categories on the Red List are included in the calculation of the RLI. As a result, the RLI is geographically highly representative, with the current RLI based on assessment of 9870 species, or 99.4% of the world's living bird species. Sixty species classified as Data Deficient are excluded.

3.5 Data timeliness

The indicator is current to December 2012.