© John Clare

The International Union for Conservation of Nature (IUCN) ‘Red List’ is designed to help conservationists and policy-makers keep track of species’ conservation status. There’s just one problem: there’s an awful lot of species. With so many described species, it’s almost impossible for each and every one to be assessed, especially given time and funding constraints. Hence there are the ‘Not Evaluated’ (NE) and ‘Data Deficient’ (DD) categories, in addition to the other seven. While the NE category simply indicates a species hasn’t been assessed, the DD category means that, while an assessment has been attempted, there wasn’t enough data available for it to be completed.

This is concerning for conservationists, especially because a significant proportion of species in all but the most-studied taxa are classified as DD. Without classification, it’s unknown whether these species need protection or not, and this risks many DD species being overlooked by conservation policy and actions.

Sam Howard and David Bickford from the Department of Biological Sciences, National University of Singapore, realised the importance of this problem and, in a recent study, developed an approach to predict what IUCN category these DD species would be in, were their assessments to be completed. They chose to focus on amphibians, both the group with the most DD species and the most threatened vertebrate group, with a third of all known species at risk of extinction and the majority experiencing declines in population. The authors developed a model that predicted the extinction risk of DD species using existing data on life history traits, environmental variables and habitat loss, and found some important results.

First, that 63% of DD amphibians would be in the IUCN threatened categories – Extinct (EX), Extinct in the wild (EW), Critically endangered (CR), Endangered (EN), Vulnerable (VU) or Near threatened (NT) – were they to be formally assessed. This is significant, as only 32% of current formally assessed species are in these categories. In other words, not only are amphibians the most threatened vertebrate group, but their risk of extinction has been substantially underestimated.

Second, by examining the areas where the predicted risk for DD species exceeded that for formally assessed species, the authors were able to identify locations which should be a focus for further research. This is because, in these areas (which primarily occur in the Andes of Western South America, the Central Africa region, Madagascar and the Indo-Burma/Chinese mountain regions), conservation priorities based on current knowledge are likely insufficient and overlook a number of highly threatened species. Urgent measures are needed in these places to obtain the data necessary to formally classify the species that are there; if this is done, they can begin to be incorporated into international conservation policy.

Finally, one particular prediction was that the rhacophorid frog, Pseudophilautus semiruber, endemic to Sri Lanka, would be extinct. While it was extant in 2012, it is likely to be highly threatened and so should be a particular focus for conservationists.

These findings are important and may help the IUCN to decide which DD species should be prioritised for classification. If this isn’t done, there’s a risk that many DD species, like Pseudophilautus semiruber, may go extinct, without us ever knowing enough to try and protect them.

September 9, 2014