A response to Ocampo-Peñuela et al. (2016); Science Advances
The IUCN Red List reflects threats to birds and other species accurately based on the latest available science, while continually working to incorporate information from the latest monitoring techniques into its species assessments.
A recent scientific study claimed that the Red List could be underestimating the number of species at risk. The study found a higher number of threatened species of birds when using an estimate of their ‘remaining suitable habitat area’ based on remote sensing data, and concluded that this was because the Red List was not estimating habitat area accurately enough.
In fact, the higher number of threatened species the study arrived at was mostly due to the fact that it used the ‘remaining suitable habitat area’ incorrectly when assessing the extinction risk of species.
The ‘suitable habitat area’ should have been applied to the ‘area of occupancy thresholds (IUCN criterion B2) but the study instead mistakenly applied it to ‘extent of occurrence’ thresholds (IUCN criterion B1), which are an order of magnitude larger than ‘area of occupancy'. This is why the study concluded that the thresholds were met for many more species than are actually threatened with extinction.
Ocampo-Peñuela et al. incorrectly state that the IUCN does not take advantage of new technologies. In reality, IUCN is already making use of new technologies, and continues its efforts to integrate new technologies into assessments. For example, Tracewski et al. (2016) published an analysis of over 11,000 species—all forest-dependent birds, mammals and amphibians worldwide—calculating their extent of suitable habitat using the same high resolution tree-cover data but correctly comparing the results with the B2 rather than B1 thresholds. The results of the Tracewski et al. study are feeding into updates of the IUCN Red List that will be published in 2017 (birds and mammals) and 2018 (amphibians).
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