XI.

Endangered Mammals

In today's rapidly changing world, many wild mammals face an increasingly difficult struggle for survival. Data released in 1996 by the World Conservation Union (also known as IUCN) indicates that of about 4600 species of mammal known to exist, over 1000 are classified as being at risk for extinction (see Endangered Species).

The number of mammal species becoming extinct has increased consistently over the last few hundred years. The quagga, an African relative of the zebra, died out in 1883, following in the footsteps of the African bluebuck, which became extinct in 1800. During the preceding century, Steller's sea cow, an inhabitant of the Bering Sea, died out in 1768. This relative of today's manatees and dugongs could weigh over 5 metric tons, making it the largest animal to have become extinct in modern history. Some of these animals vanished as a result of hunting, others through competition from other species. Several species of mammals have become extinct in the 20th century, including the Caribbean monk seal, which was last seen in 1952; at least four species of bats; and eight species of marsupials, including the thylacine, which disappeared when the last captive animal died in 1936.

Today hunting still poses a danger to some species, particularly animals such as elephants, rhinoceroses, and tigers, which fetch high prices on the black market for their tusks, horns, and other body parts. During the past 30 years alone, the population of black rhinos has dropped by over 95 percent, and the number of tigers has been reduced to about 5000. International efforts have helped to stem the trade in products from these animals, but without further intervention, their future as wild species remains in doubt.

For mammals as a whole, a more important threat is habitat change. Deforestation threatens a third of the world's primates, while urbanization, agriculture, and water pollution have had a serious effect on a wide range of mammals, from prairie dogs to aquatic species such as otters and river dolphins. In the drive to reverse this decline, some mammals have become the focus of preservation programs aimed at increasing stocks by habitat management, and also by captive breeding.

These programs have saved several species from almost certain extinction. Mammals rescued in this way include the giant panda, which has become a worldwide emblem of wildlife preservation, the white-throated wallaby, and also the North American black-footed ferret, which was once regarded as an agricultural pest. By the late 1970s, the black-footed ferret was believed to be extinct, but a small colony of survivors was discovered in 1981. Over 400 animals now live in captivity, and a number have been released into the wild.

After centuries of exploitation, some marine mammals have also been helped by recent protective legislation. The gray whale, for example, once seemed certain to become extinct, until hunting was banned by the International Whaling Convention in 1946. Since then, the numbers of gray whales in the Pacific Ocean have risen to about 20,000, which may be close to the population before hunting began. The Cape fur seal, which breeds on the rocky coasts of southern Africa, has shown an even more dramatic increase, growing from a few thousand in the 1930s, when it was first given protection, to over 1 million today. In the United States, the Endangered Species Act of 1973 prohibits federal projects from destroying the habitat of any endangered species.