New species of reptiles continue to be discovered. This is especially true of lizards. Hence the numbers that follow are approximations subject to change. We currently recognize 285 species of turtles, 23 crocodilians, two tuatara, 4,450 lizards, and 2,900 snakes. One of the authors of this chapter (H. M. S.) has named approximately 300 species in his career and is working on projects that will almost certainly add species to the list. In countries such as the United States, where numerous herpetologists have studied the fauna thoroughly, it is relatively unlikely that new species will be dis covered. Nevertheless, herpetologists sometimes find reasons to justify the splitting of previously recognized species into two or more species. Third World countries present an entirely different situation because they possess few indigenous herpetologists, and some of these countries have only rarely been visited by herpetologists. Consequently, new species are quite likely to be found in these lands, especially those in the tropics and subtropics. It has been estimated that in most such countries, approximately 30% of the reptile fauna remains to be discovered. Thus much basic work remains to be done. At the same time, we must be mindful of the rate at which species are currently being lost to deforestation, habitat fragmentation, pollution, overharvesting, invasion of harmful exotic species, and other anthropogenic causes. We are now facing a situation in which we are losing species to extinction before they have been given proper scientific names. During the past decade, amphibian biologists have justifiably called attention to the worldwide decline of many salamanders and anurans. Without doubt this is a serious problem, but it has overshadowed the fact that reptiles have been suffering the same fate.
Many of the same factors responsible for amphibian declines have been insidiously working their decimating effects on reptiles. At the heart of the problem is the human population, now much more than six billion, and a drastically uneven distribution of resources. Many people living in areas of high reptile diversity are unable to eke out a living and are therefore tempted to exploit their native fauna, legally or illegally, and to engage in other economic activities that eventually have negative repercussions on the fauna. Hunting of reptiles occurs for local consumption, sale of hides or shells, sale of live animals to the pet trade, and sale of meat or other body parts as exotic food or medicines. China has almost extinguished its turtle fauna, for example, and has put catastrophic pressure on the turtle population in the rest of Southeast Asia. Chinese dealers also purchase several species of turtles during their active seasons in North America, particularly snapping turtles and softshells, for shipment to Asia. A team of biologists conducting a survey of tortoises in Madagascar found hundreds of dead animals, all with their livers removed. Local rumor revealed that these organs are made into an exotic pâté that is shipped to Asia. Although the mathematics of sustainable harvesting have been well worked out and can provide the basis for enlightened commercial practices and population management, the rate at which turtles have been harvested in China, Southeast Asia, Madagascar, and elsewhere is greatly exceeding the rate required for sustainable yields.
A similar situation developed in connection with hides of various reptiles, including crocodilians and several large lizards and snakes. In the case of crocodilians, management programs aimed at providing sustainable yields were developed in several countries, and these measures proved successful, so much so that the species involved recovered from endangered status. This experience indicates that the conservation strategy of management for sustainable yield can work if it is carefully implemented on the basis of good ecological and demographic data and if the harvest is carefully monitored. Enthusiastic participation of local people is an important element of the success of such programs as they have been carried out in Africa, Asia, and South America. It may not be too late to put these ideas into practice to save the turtle fauna of Asia. In the case of the crocodilians, declining populations quickly allowed several secondary events, such as explosive growth in populations of fish that were prey of crocodilians and reductions in populations of fish that depended on the deep holes made by crocodilians. An added benefit of sustainable yield programs was that these pertur-
bations were reversed as the crocodilian populations were restored. It is probable that secondary effects of Asian turtle harvesting will make themselves known in the near future because turtle burrows are homes for a variety of other creatures. Eliminating turtles makes the ecosystem inhospitable for animals that depend on turtles. In short, enlightened management may be a tool for creating sustainable yield and for habitat restoration.
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