One in Four Mammals at Risk of Extinction

Kimberly Johnson
for National Geographic News
October 6, 2008
One in four of the world's 5,487 known mammal species face extinction, according to a new conservation "report card" unveiled today.

Marine mammals face even steeper odds, with one in three species at risk of disappearing, according to the study.

The assessment, done as part of the International Union for Conservation of Nature's (IUCN's) Red List of Threatened Species, took more than 1,700 experts from 130 countries five years to complete.

The report's findings were released today in conjunction with this week's IUCN meeting in Barcelona, Spain, and will appear later this week in the journal Science. "Our results paint a bleak picture of the global status of mammals worldwide," the study authors wrote.

(See photos of animals on the new list.)

Humans are mostly to blame, as habitat loss, pollution, and hunting continue to squeeze at-risk species.

Under Threat

The new report updates the last IUCN survey conducted in 1996 and adds 700 species not previously assessed.

"Perversely, the species that humans show greatest affinity toward—the largest mammals such as primates, big cats, and whales—are significantly more likely to be threatened with extinction," Barney Long, a biologist at the World Wildlife Fund in Washington, D.C., said in an email.

Some of the most threatened species are found in Asia, a region undergoing rapid human population and economic growth.

"This is leading to habitat loss due to agricultural expansion; development of infrastructure such as roads, which fragment critical landscapes; and increasing areas for industrial crops such as oil palm and pulp for paper," said Long, who helped create the new assessment.

Currently, 79 percent of Asia's primate species face extinction.

(Read: "Extinction Threatens Half of Primate Types, Study Says" [August 5, 2008].)

Worldwide, habitat loss affects roughly 40 percent of threatened mammal species, while human hunting affects 17 percent, Long said.

Seventy-eight percent of marine mammals are threatened by accidental deaths, such as becoming bycatch in fishing nets intended for other species.

Marine mammals are "threatened purely because humankind does not care enough to mitigate deaths that do not even benefit our species," Long said.

"All these threats represent human-driven activities that, if not controlled, will soon lead to a dramatic increase in the 76 species of mammal that are known to have gone extinct since 1500," Long said.


Timothy Ragen is executive director of the U.S. government's Marine Mammal Commission in Bethesda, Maryland.

"We are causing a period of excessive decline or loss in the diversity of nonhuman life over time," he said, adding that the problem will only get worse as human populations grow.

"If we expect to be good stewards, we will have to reexamine our relationship with other forms of life and be willing to make the changes needed to conserve our natural world," Ragen said.

The IUCN Red List is apolitical in scope, but political will is required to reverse species' downward spirals, added lead study author Jan Schipper, director of global mammal assessments for IUCN and the nonprofit Conservation International based in Arlington, Virginia.

"The species that are recovering are the ones we're focusing restoration and recovery efforts on," he said.

According to the report, 5 percent of threatened species have seen rebounds due to conservation efforts.

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