New 'distance to extinction' index could sharpen conservation focus

A paper published in the journal Frontiers in Ecology and Environment has put forward a new way to measure how close a species may be to extinction. The measure, known as the SAFE index (for Species Ability to Forestall Extinction) takes a different approach to the widely used 'Red List of Threatened Species'. But the authors, from Australia's University of Adelaide and James Cook University, are keen to stress that this new index is complementary to the Red List. Used together, both measures could help to sharpen the focus of conservation efforts.

The need to carefully track the health of wildlife species, worldwide, as they come under repeated pressure from man's activities, has long been recognized. The current Red List system was developed by the International Union for Conservation of Nature (IUCN) in 1994, to replace an older approach in place for some 30 years beforehand. The Red List looks at how fast a species is losing numbers - or how small a population or area is left to it - in order to decide which 'risk category' it belongs to.

But the numbers used in the Red List, to decide whether a species is Critically Endangered, Vulnerable or Near Threatened, don't vary from species to species. That means they may paint too broad a picture to help conservationists decide where to put scarce resources. The SAFE index, proposed in this new paper, uses the a species-specific measure - the minimum viable population - as a base to make itself relevant at the species level.

Paper co-author, Professor Corey Bradshaw, from the University of Adelaide, explains the approach that SAFE uses ''The idea is fairly simple - it's the distance a population is (in terms of abundance) from its minimum viable population size. While we provide a formula for working this out, it's more than just a formula - we've shown that SAFE is the best predictor yet of the vulnerability of mammal species to extinction.''

An example of the use of the SAFE index is in deciding which of 2 threatened rhinoceros species to make a priority for help. The Red List has both the Sumatran and Javan rhinos as Critically Endangered, but the SAFE index shows that the Sumatran rhino is in a better position to recover. That could make it the best species to focus in on. With resources to conserve endangered species often tight, the more tools the beleaguered conservationist has to hand, to prioritize their rescue, the better.