TCS Daily

Tigers and Rhinos and Pandas, Oh My!

By Iain Murray - May 28, 2002 12:00 AM

There's a reason the World Wildlife Fund uses a Giant Panda as its symbol. An endangered, attractive mammal is a magnet for sympathy. They would never think of using a burrowing insect or a slimy mould, however endangered they were.

So it is not surprising that media the world over found the claim that a quarter of the world's mammal species faced extinction the most important aspect of the United Nations Environment Program's (UNEP) new report on the outlook for the environment over the next 30 years. The Associated Press began its story with the claim "A quarter of the world's mammal species -- from tigers to rhinos -- could face extinction within 30 years," while The Independent of London argued that this was evidence of a "sixth wave of mass extinction." These extravagant claims, however, are hard to back up with hard data.

The UN claims 11,000 species face extinction over the next 30 years, including one quarter of all mammals (1,130) and 12 percent of birds (1,183). These figures, though, seem remarkably high when we compare them to the historic evidence. We have pretty good data about extinctions of the higher species -- mammals and birds -- since about 1600 AD, and a quick look at those figures puts the environmentalists' claims into perspective. There are about 4,500 documented mammalian species, but only 110 have gone extinct in the past 400 years. Similarly, there are about 9,500 species of bird, with only 103 recorded extinctions. In this era of conservation, when we know more about what causes extinctions than ever before, the suggestion that the extinction rate might increase so violently flies in the face of logic.

In fact, the total rate of extinctions claimed by UNEP -- about 11,000 species over the next thirty years -- is not far off what reasonable estimates of the problem suggest. Models based on experimental data rather than theories suggest a modern extinction rate of about 0.7 percent of species over 50 years. We would therefore expect around 11,000 extinctions among the 1,500,000 documented species we currently monitor. However, only about 30 of these would be mammals and 70 birds. The vast majority of extinctions would be among insect life. UNEP, however, does not categorize many insect species as being threatened, which is probably an artifact of how much attention is paid to these species. The rules for categorizing a species as endangered, for instance, include specific measures in square kilometers of the animal's habitat. These numbers take no account of the size of animal, an obvious bias towards the bigger animals.

This area of research is prone to wild exaggerations. Dr. Norman Myers made headlines in 1979 when he claimed that the earth experiences 40,000 extinctions a year. However, this figure simply results from dividing a totally speculative figure of 1,000,000 extinctions in the last quarter of the century by 25. Dr Myers had no basis for claiming the figure of 1,000,000 extinctions. The best available data he had at the time suggested that 1 species per year had gone extinct up to 1900, which might have increased to 100 a year by 1974. The 40,000 figure, however, entered popular consciousness, and has been repeated and exaggerated even further by other scientists. Famed biologist E.O. Wilson puts the figure at between 27,000 and 100,000 a year, while in 1981 Paul Ehrlich of "The Population Bomb" fame estimated 250,000 extinctions a year.

To the extent that the UNEP researchers have toned down the claims of Myers, Wilson and Ehrlich, they are to be congratulated. What they have done instead, however, is to play up the threats to the "cuddly" animals -- mammals and birds -- and thereby maximize media attention. The media, for their part, have ignored the nuances of the UNEP report. If an animal is "threatened" that does not mean it is on the verge of extinction. According to the latest figures from the World Conservation Monitoring Center, only 169 species of animal and 168 species of bird are "critically endangered." Thankfully, it is those species that are among the most protected in the world. These data make clear just how realistic claims of a "sixth mass extinction" really are.


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