Threats to Species Accelerate

by Elroy Bos

According to IUCN–The World Conservation Union, in its latest assessment of the state of life on our planet, the number of known threatened species reached 16,118 in 2006.1 The ranks of those already facing extinction were joined by familiar species like the hippopotamus and desert gazelles, along with ocean sharks, freshwater fish, and Mediterranean flowers.2 By now, 784 species on Earth have been declared extinct, and a further 65 are found only in captivity or cultivation.3

Of the 40,168 species assessed using the IUCN Red List criteria, one in three amphibians, a quarter of the world’s coniferous trees, one in eight birds, and nearly one in four mammals are now known to be in jeopardy.4 (See Table 1.) The term “threatened” includes three Red List categories of escalating threat: vulnerable, endangered, and critically endangered.

These numbers from the 2006 IUCN Red List of Threatened Species demonstrate the ongoing decline of global biodiversity and the impact that humankind is having on life on Earth. Additions to the list in 2006 included a particularly familiar face—the polar bear. This charismatic mammal is now classified as vulnerable, as it is set to become one of the most notable casualties of Earth’s rising temperature. The impact of climate change is increasingly felt in polar regions, where summer sea ice is expected to decrease by 50–100 percent over the next 50–100 years.5 Polar bears are predicted to suffer more than a 30-percent population decline in the next 45 years as the ice floes they depend on when they hunt seals slowly disappear.6

Escalating threats to desert wildlife are unregulated hunting and habitat degradation. The dama gazelle of the Sahara, which was listed as endangered in 2004, has suffered an 80-percent crash in numbers over the past 10 years because of uncontrolled hunting and is now deemed critically endangered.7 Other Saharan gazelle species are also threatened and seem destined to suffer the fate of the scimitarhorned oryx: extinct in the wild.8

In 2006, the Red List also included comprehensive regional assessments of selected marine groups. Sharks and rays are among the first such groups to be systematically assessed; of the 547 species evaluated so far, 20 percent are threatened with extinction.9 This confirms suspicions that these mainly slow-growing species are extremely susceptible to overfishing and are disappearing at an unprecedented rate.

The plight of the angel shark and common skate, once familiar sights in European fish markets, illustrates dramatically the recent rapid deterioration of many sharks and rays. They have all but disappeared from sale.10 The angel shark (moved from vulnerable to critically endangered) has been declared extinct in the North Sea, and the common skate (moved from endangered to critically endangered) is now very scarce in the Irish Sea and the southern North Sea.11

Freshwater species are not faring much better. They have suffered some of the most dramatic declines: 56 percent of the 252 endemic freshwater Mediterranean fish are threatened with extinction, the highest proportion in any regional freshwater fish assessment so far.12 Seven species, including carp relatives Alburnus akili in Turkey and Telestes ukliva from Croatia, are now extinct.13 Of the 564 dragonfly and damselfly species so far assessed, nearly one in three are threatened, including nearly 40 percent of endemic Sri Lankan dragonflies.14

Larger freshwater species, such as the common hippopotamus, are also in difficulty. One of Africa’s best known aquatic icons, it has been listed as threatened for the first time and is classified as vulnerable, primarily because of a catastrophic decline in the number of hippos in the Democratic Republic of the Congo.15 In 1994 this country had the second largest hippo population in Africa—30,000 after Zambia’s 40,000—but today numbers have plummeted by 95 percent due to unregulated hunting for meat and the ivory in hippo teeth.16

The IUCN Red List of Threatened Species has become an increasingly powerful tool for conservation planning, management, monitoring, and decision-making. It is used by government agencies and nongovernmental organizations in at least 57 countries to compile national Red Lists and is a focus for conservation action.17

Against the catalogue of decline, the latest data also show that conservation action does work. Following signifi- cant recoveries in many European countries, the numbers of whitetailed eagles doubled in the 1990s, and this species has been moved from the near threatened category to of least concern.18 Enforcement of legislation to protect the species from being killed and measures to address threats from habitat changes and pollution have resulted in increasing populations.19

On Australia’s Christmas Island, the seabird Abbott’s booby was declining due to habitat clearance and an introduced invasive alien species, the yellow crazy ant, which had a major impact on the island’s ecology.20 The booby, listed as critically endangered in 2004, is recovering thanks to conservation measures and has now been moved to the endangered category.21

Other plants and animals highlighted in previous Red List announcements as under threat are now the focus of concerted conservation actions, which it is hoped will improve their conservation status in the near future. Some noteworthy examples are the 300-kilogram Mekong catfish of Southeast Asia, the Indian vulture, the humphead wrasse, and the Saiga antelope.22

These examples also illustrate a valuable lesson: bringing about the recovery of species on the edge of extinction is much more difficult and costly than preventing the decline in the first place by, for example, protecting habitat. They also underline the need for reliable scientific data on the status of species to guide recovery efforts and for quicker responses by governments and civil society when species or habitats come under threat.

Includes the following charts and graphs
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Notes
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