Farther north in Africa, the dama gazelle of the Sahara region has suffered an 80 percent decline in the past decade because of uncontrolled hunting.
Nor are land animals the only ones experiencing such declines.
Among sea creatures, the IUCN took a close look at sharks and rays, finding that one-fifth of the 547 species it assessed are threatened with extinction, probably due to overfishing.
"Marine species are proving to be just as much at risk of extinction as their land-based counterparts," said Craig Hilton-Taylor of the IUCN Red List Unit in a statement.
The Red List is the best worldwide system for ranking endangered species, even though it conveys no direct protection to any of the listed species, said Kieran Suckling, policy director for the Center for Biological Diversity, in Tucson, Arizona.
Other ranking systems, he said, are subject to political pressures that can skew the results.
"Here you have an unbiased, objective account," he said. "There's no guesswork and no political pressure. The listings tend to focus conservation energy."
The Red List now contains 40,177 species, 16,119 of which are categorized as critically endangered, endangered, or vulnerable.
Large as those numbers are, they represent only a fraction of the world's species, estimated to total somewhere between 10 million and 100 million.
Not All Bad News
The Red List update included good news for some species.
Of particular note, the IUCN found that swift conservation action has given Indian vultures a more hopeful future.
These birds, once numbering in the millions, had been accidentally poisoned by feeding on animal carcasses contaminated with a veterinary arthritis drug.
The drug, Hilton-Taylor said, has now been banned in India, and scientists are working to establish captive-breeding colonies that can be used to reintroduce the birds into the wild.
Also of note is the recovery of the white-tailed eagle, which was downlisted from "near threatened" to "least concern" due to increased protection efforts in Europe.
"These examples show that conservation measures are making a difference," Achim Steiner, the IUCN's director general said in a statement.
"It's not just the world's governments that need to be doing more," Hilton-Taylor said.
"It's everybody. Every little bit helps."
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