12 March 2009

Red List unscientific and frequently wrong?

So claim a growing number of conservation scientists, including several who help compile it. Criticism recently came to a head in a series of articles in the journal Endangered Species Research.

While no one wants to see an end to the Red List, which covers 45,000 species, many fear that the sometimes shaky methods behind the creation of the listings are downplayed, meaning time, money and effort can be misdirected trying to save "safe" species while others creep towards extinction.

Extinction risks are calculated according to IUCN criteria, such as whether the rate of decline in species numbers has passed certain thresholds.

These criteria can throw up oddball results. The green turtle, for example, is listed as endangered despite a global population of over 2 million. "Green turtles are not going to disappear," says Brendan Godley of the University of Exeter, UK, and the Marine Turtle Specialist Group. That doesn't mean we should ignore them - some populations are at serious risk from egg harvesting, for instance. "It's just not the same level of risk as a population of 50 parrots living on a small island that is being deforested."

An additional "critically declined" category was also suggested, which would act as an alert without making judgments about extinction risk.

"Thresholds are geared towards mammals," says Atte Komonen of the Swedish University of Agricultural Sciences in Uppsala. "A thousand elephants might well be viable, but 1000 beetles is very unlikely to be, not least because they might occupy a single tree that could go up in smoke." The solution would be to tailor risk to specific taxonomic groups, Komonen suggests, in this case measuring the number of occupied trees rather than individuals.

One argument against tailoring methods to individual species is that it would make it difficult to compare relative extinction risks.

But the problems may run deeper. Some scientists claim that a tendency to abide by the "precautionary principle" - encouraged by Red List guidelines - means that specialist groups end up demanding higher levels of proof for an increase in numbers than a decrease, ultimately exaggerating extinction risks. "There's a tension between following scientific principles or precautionary conservation principles," says Webb.

Good field data can also be hard to come by, and the fact that the list is "cobbled together" by volunteers only exacerbates this problem.

For many species, a lack of data means no assessment at all or relegation to the "data deficient" category. The Amazon river dolphin, for example, recently shifted from "vulnerable" to "data deficient". The IUCN emphasises that this does not mean a species is in the clear, but the listing might not be helpful. "Data deficient species tend to be neglected in terms of conservation management," says Steven Garnett, also at Charles Darwin University in Darwin.

Full articles on the wildsingapore news blog.

The Red List in Singapore

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