Our Extinction Problem May Be Far, Far Worse Than We Think
The sharp decline of land snail species in Hawaii may have frightening implications for the extinction rates of animals worldwide.
A multinational team of researchers argue that because the International Union for Conservation of Nature’s Red List — often cited as the authority on extinct and endangered species worldwide — does not look at most invertebrates, it presents a skewed picture of extinction rates, portraying them as much lower than they are.
“The focus on birds and mammals and the proportionately negligible assessment of invertebrates masks a real crisis,” the researchers write in a paper published in the journal Conservation Biology in July.
Fewer than 1 percent of invertebrates worldwide have even been evaluated by the IUCN. Yet invertebrates constitute 95 to 99 percent of animal species, including insects, worms, snails and crustaceans — meaning there’s a lot of species that haven’t been assessed.
The researchers note that the IUCN standards for evaluating invertebrate species are so stringent that assessing many of them is virtually impossible — a problem that’s been pointed out by other scientists in the past.
In order to estimate the gap between extinction rates reported by the IUCN and real extinction rates, the researchers set out to conduct their own comprehensive survey of 325 known Hawaiian land snail species and compare their findings with the numbers listed by the IUCN.
While the IUCN cites 33 Hawaiian land snail species as extinct, the newer study concludes there are 131 extinct species. Extinction rates haven’t been constant, researchers say, but have risen in connection with periods of habitat destruction and introductions of invasive species by humans.