Using Red List Indices to measure progress towards the 2010 target and beyond

Abstract

The World Conservation Union (IUCN) Red List is widely recognized as the most authoritative and objective system for classifying species by their risk of extinction. Red List Indices (RLIs) illustrate the relative rate at which a particular set of species change in overall threat status (i.e. projected relative extinction-risk), based on population and range size and trends as quantified by Red List categories. RLIs can be calculated for any representative set of species that has been fully assessed at least twice. They are based on the number of species in each Red List category, and the number changing categories between assessments as a result of genuine improvement or deterioration in status. RLIs show a fairly coarse level of resolution, but for fully assessed taxonomic groups they are highly representative, being based on information from a high proportion of species worldwide. The RLI for the world's birds shows that that their overall threat status has deteriorated steadily during the years 1988-2004 in all biogeographic realms and ecosystems. A preliminary RLI for amphibians for 1980-2004 shows similar rates of decline. RLIs are in development for other groups. In addition, a sampled index is being developed, based on a stratified sample of species from all major taxonomic groups, realms and ecosystems. This will provide extinction-risk trends that are more representative of all biodiversity.Keywords: indicators; birds; amphibians; IUCN Red List; threatened species; extinction-risk IUCN RED LISTThe World Conservation Union (IUCN) has published lists of species at risk of extinction since the 1950s, compiling these as Red Data Books since the 1960s and as Red Lists since the 1980s. Initially, species were assigned to qualitatively defined categories. To improve objectivity and consistency of application (Fitter & Fitter 1987) the IUCN Species Survival Commission initiated the development of quantitative criteria in 1989. After several rounds of review and revision, a system was adopted in 1994 (IUCN 1994), with further revisions published in 2001 (IUCN 2001).There are three principal categories for species at high risk of extinction: critically endangered, endangered and vulnerable. Species are assigned to a category if they meet the appropriate quantitative threshold for at least one of five criteria (table 1). Four criteria are based on the size and rate of decline of the population and/or geographical range, with the fifth relating to quantitative models of extinction-risk such as population viability analyses. Precise information is not essential to apply the criteria: assessors can use expert knowledge along with the best information available to make estimates about the relevant parameters, so long as the uncertainties are explicitly specified (IUCN 2001). Species close to qualifying for the thresholds for vulnerable are classified as near threatened (although there are no definitive quantitative thresholds for this category, guidelines are given). Extinct species are categorized as extinct in the ...

The 2010 challenge: data availability, information needs and extraterrestrial insights

“…First, the majority of the schemes make use of data collected for other purposes (Loh et al 2005 Butchart et al 2005). This means they are potentially unrepresentative (from the perspective of the 2010 target) in their coverage.…”

“…There is considerable scope for the development and wider implementation of improved methods (Buckland et al 2005) for post-stratification, and the calculation of indicators, but indicators that depend upon incomplete existing data collected for other purposes will always be weakened by the impossibility of excluding all potential sources of bias. In other cases, data are either complete (the Red List Index of Butchart et al 2005), or made up of a carefully chosen sample (Gregory et al 2005;Mayaux et al 2005; and the scheme proposed by Nic Lugadha et al 2005). However, even in these cases, it is important to assess critically the wider representativeness of the data (e.g.…”

“…However, even in these cases, it is important to assess critically the wider representativeness of the data (e.g. what can we infer about overall extinction risks from those of mammals, birds and amphibians (Butchart et al 2005), and are common farmland birds representative of farmland biodiversity as a whole (Gregory et al 2005…”

The changing fates of the world's mammals

“…An important aspect of the RLI is that it can be disaggregated according to geography, taxonomy and ecology to show trends at finer scales [33,34]. Disaggregated by biogeographic realm (following the classification of Olson et al [48]), the RLI shows that the rate of deterioration has been most severe in the Indomalayan (22.0%) and Australasian (21.4%) realms (figure 1).…”

“…The RLI is calculated from the change in IUCN Red List categories of all assessed species in a taxon over time [33][34][35]. To avoid introducing errors owing to non-genuine changes in categories discussed above, the RLI only considers genuine deteriorations (i.e.…”