In defence of the Red List

Jeff McNeely, Simon Stuart, Jane Smart and Jean-Christophe Vié
New Scientist 3 Apr 09;

THE IUCN's Red List of Threatened Species is widely recognised as one of the best tools we have for guiding nature conservation. It is widely used to identify species in need of conservation measures and sites of crucial importance for biodiversity, and also to track progress on reducing biodiversity loss and to guide resource allocation. It is not perfect and no stranger to criticism, most recently in the pages of this magazine, where it was described as "unscientific and frequently wrong" (New Scientist, 14 March, p 8). This is wide of the mark.

The first IUCN Red Data Book was published in 1963 as an essentially subjective list of extinction risks. Over the past 45 years it has evolved considerably. It is no longer simply a register of species and their level of risk, but a rich compendium of information on where species live, their ecological requirements, the threats they face and the conservation actions that can be used to prevent them becoming extinct. It also covers common species, not just threatened ones.

As such, the Red List helps to answer many important questions. What is the overall status of biodiversity and how is it changing over time? What is the rate at which biodiversity is being lost? Where is biodiversity being lost most rapidly? What are the main drivers of the loss of biodiversity? What is the effectiveness and impact of conservation activities?

While we at IUCN welcome constructive criticism, we are exasperated by critics who fail to recognise the steady improvements IUCN has been making in trying to present an objective picture of the conservation status of species worldwide, as well as helping to ensure that biodiversity loss is recognised as a crucial issue at the highest political levels.

In recent years, a large number of articles have been published in the scientific literature championing the Red List's merits (for example Trends in Ecology & Evolution, vol 21, p 71). No other conservation tool can claim the same level of rigour, the same degree of transparency and the same amount of debate and consultation. It is important to note that the Red List is one of the very few biodiversity indices, if not the only one, for which the methodology has been published in a peer-reviewed scientific journal (PLoS ONE, vol 2, e140).

One oft-repeated criticism is that the list is excessively cautious because it assigns too many species to a category labelled "data deficient", meaning there is not enough information to assess conservation status. This is a weak argument. Rather than rushing to a judgement based on poor data, we highlight those species that need more research before an objective decision can be made. Handling uncertainty in a structured way is not common practice in the conservation world, but this is what the Red List does. Given the magnitude of the extinction crisis there is a need to provide sound advice to decision-makers who are pressing scientists to inform them about the state of biodiversity.

Similarly, we have heard arguments faulting the Red List for assigning extinction risk based on how fast a species is declining, rather than on absolute numbers. While this can lead to species such as the green turtle being listed as endangered when there are still more than 2 million individuals, criticising it on these grounds is misleading. Decline is a key indicator of extinction risk. As many conservation experts can attest, there are numerous instances of formerly abundant species declining to extremely low levels very rapidly - think of American bison and passenger pigeons in the past and, more recently, Asian vultures and saiga antelope.

Both these criticisms were addressed in a major paper that appeared in Conservation Biology last year (vol 22, p 1424). It was disappointing to see New Scientist repeating them without reference to that paper.

One criticism in the article was new even to us: that the Red List diverts resources away from species that really need them. This argument is baseless. It is like accusing humanitarian organisations of putting children in Eritrea at risk because they are publishing a report on Darfur.

Of course, the Red List is open to improvement. IUCN regularly convenes a group of respected scientists to review and refine the system, and its guidelines are constantly updated to reflect the latest scientific thinking and insights. One important issue this group is working on at the moment is how to integrate climate change into the listing process. Our preliminary results show that a large number of species that do not currently appear as threatened on the Red List are susceptible to climate change.

The Red List remains the most accurate tool for measuring the state of species. The fact that it is based on the work of more than 7000 scientists does not mean it is "cobbled together". It makes it richer, with an unparalleled reach. Yes, it is open to debate and challenge, but the diversity of the sources it draws on makes it unique and irreplaceable. There are countless examples showing that, where used properly, it can be deployed to develop conservation programmes that have enormous benefits.

It is extremely difficult to raise awareness among decision-makers about the crucial importance of giving attention to all life forms on our planet. Everybody in the conservation movement wants biodiversity to receive the same level of attention as climate change, but this is no easy task. The Red List, thanks to its objectivity and high standards, is one of the very few tools that could allow this to happen.

Jeff McNeely is chief scientist of the International Union for Conservation of Nature (IUCN). Simon Stuart is chair of IUCN's species survival commission. Jane Smart is head of IUCN's biodiversity conservation group. Jean-Christophe Vié is deputy head of IUCN's species programme