The Red List Index: measuring global trends in the threat status of biodiversity

Richard Thomas / BirdLife Black-browed Albatross Thalassarche melanophrys, one of the species most affected by longline fishing Zoom In

BirdLife and the other partners in the Red List Consortium have developed Red List Indices based on the IUCN Red List (the most authoritative and objective system for classifying species in terms of their risk of extinction). The Red List Index (RLI) illustrates the relative rate at which species in a particular group change in overall threat status (i.e. projected relative extinction risk), as quantified by Red List categories, over periods of around five years.

• Red List Indices are robust and powerful tools for measuring biodiversity loss – they are already being used to track progress towards the 2010 target.
• RLIs illustrate the relative rate at which sets of species change in overall threat status (i.e. projected relative extinction risk), based on population and range size and trends as quantified by categories on the IUCN Red List.
• RLIs are based on the number of species moving between categories owing to genuine improvement or deterioration in status.
• The overall threat status of the world's birds has deteriorated steadily during 1988–2004. A preliminary RLI for amphibians for 1980–2004 shows similar rates of decline.
• By 2010, RLIs will be available for at least mammals, birds, amphibians and cycads, plus first assessments for reptiles, fish, freshwater molluscs, dragonflies, palms and legumes.
• A sampled RLI is also being developed, based on a stratified sample of species from a broad suite of major taxonomic groups, realms and ecosystems. This will provide trends in extinction risk more representative of all biodiversity.

The Red List Index for the world's birds

• There has been a steady and continuing deterioration in the threat status (projected extinction risk) of the world's birds between 1988 and 2004.

RLI for the world's birds

• Birds in the Indomalayan realm show a steeper rate of deterioration during the 1990s, owing to intensifying deforestation in the Sundaic lowlands of Indonesia.

RLI for birds in different biogeographic realms

• Albatrosses and large petrels have undergone recent steep declines, linked to expansion of commercial longline fisheries, which causes incidental mortality when seabirds get caught on baited hooks and drown.

RLI for birds covered by three international treaties

Related Links

• The Red List Index: measuring global trends in the threat status of biodiversity - leaflet (PDF, 110 KB)
• The Red List Index: measuring global trends in the threat status of biodiversity - poster (PDF, 860 KB)
• Butchart et al. (2005) Using Red List Indices to measure progress towards the 2010 target and beyond. Phil. Trans. Roy. Soc. B. 360: 255-268. (PDF, 207 KB)
• Butchart et al (2004) Measuring Global Trends in the Status of Biodiversity: Red List Indices for Birds. PLoS Biol. 2 (12): e383 (PDF, 1.7 MB)
• The IUCN Sampled Red List Index: Measuring progress towards the 2010 biodiversity targets (PDF, 900 KB)
• Summary of Measuring Global Trends in the Status of Biodiversity (PDF, 34 KB)
• State of the world's birds (pp.16-17) - Species are becoming more threatened (PDF 315 KB)
• Butchart et al. (2006) Biodiversity Indicators Based on Trends in Conservation Status: Strengths of the IUCN Red List Index Conservation Biology Volume 20, No. 2, 579–581. (PDF, 145kb)
• Butchart et al. (2007) Improvements to the Red List Index PLoS ONE 2(1): e140 (PDF, 219kb)