Many mammals threatened by extinction

Black-footed ferrets are one of the positive cases noted by the study. Credit -- U.S. Fish and Wildlife ServiceA new comprehensive study of the world’s 5,487 known mammal species indicates that extinction threatens 25 percent of land mammals and 36 percent of marine mammals.

Published October 10 in the journal Science, the study took five years to complete. More than 1,700 experts from 130 countries contributed to it. The group created a public database of the 5,487 mammal species.

The outlook is poor for some abundant species. The authors note that “52% of all species for which population trends are known are declining, including 22% of those classified as of Least Concern. These trends indicate that the overall conservation status of mammals will likely deteriorate further in the near future, unless appropriate conservation actions are put in place.”

The study was done in conjunction with an update to the Red List of threatened species, which is maintained by the International Union for Conservation of Nature (IUCN). A species listed as “Least Concern” by the IUCN is at the opposite end of the spectrum from “Extinct.”

On the positive side, the study notes that “at least 5% of currently threatened species have stable or increasing populations.” This includes the reintroduction of the black-footed ferret to the United States. It had disppeared from the wild, but thanks to captive breeding programs run by the U.S. Fish & Wildlife Service, it has been returned to the wild in eight Western states and Mexico. It is now listed as “Endangered” rather than “Extinct in the Wild.”

The United States has 440 mammal species. Indonesia has the most, with 670. South America, Africa and Southeast Asia have the largest, most diverse numbers of mammals.

What are the largest threats to mammals? “Worldwide, habitat loss and degradation (affecting 40% of species assessed) and harvesting (hunting or gathering for food, medicine, fuel, and materials, which affect 17%) are by far the main threats … ” However, for marine mammals “the dominant threat is accidental mortality (which affects 78% of species), particularly through fisheries by-catch and vessel strike.”

Land mammals in South and Southeast Asia are the most threatened, while marine mammals in the North Atlantic, North Pacific and Southeast Asia are most endangered.

There was some more good news as well. Overall, the diversity of mammals was richer than scientists thought. There were 700 new mammals not covered in the survey in 1996.

For more info, here’s a Washington Post article describing the study.

What do you think of the plight of the world’s mammals?

October 10, 2008

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Dan Kulpinski

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