Tigers, according to a new scale, should be a top priority for conservationists. Photo credit: law_keven/Creative Commons
The IUCN has established a set of categories to guide international conservation efforts. Though the scale ranges from "least concern" to "extinct" the important categories are "vulnerable," "endangered," and "critically endangered." These labels are granted based on population studies and help to prioritize species that most urgently need help.
The only problem with the IUCN Red List is that it does not offer guidance within categories. Now, a new scale developed by researchers at the University of Adelaide and James Cook University, has revealed that the range within "critically endangered" is just as significant as its proximity to neighboring Red List categories.Called SAFE (Species Ability to Forestall Extinction), the new systems builds on previous studies and creates a ranking by comparing a specie's current population to the minimum number required for survival. The greater the difference between these two numbers, the more dire the situation.
Corey Bradshaw, one of the study's co-authors, explained:
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.
SAFE is intended to be a supplement to the IUCN Red List, not a replacement.
"Our index shows that not all Critically Endangered species are equal," Bradshaw says, "a combined approach—using the IUCN Red List threat categories together with the SAFE index—is more informative than the IUCN categories alone, and provides a good method for gauging the relative 'safety' of a species from extinction."
The index also helps in conservation triage situations, deciding where limited resources can do the most good and when a species has past the tipping point.