Neglected elders.

• Author: Youth, Howard
• Position: Endangered reptile species and populations

Without the vociferous public support many other animals enjoy, reptiles may have a tough time weathering the growing threat of extinctions caused by the march of human development.

A brown spider vanishes from its leafy perch, displaced by a flashing white blur - the long, sticky tongue of a chameleon. A foot and a half away, the hunter snaps his mouth shut, then crunches down on his prey several times before swallowing. Splotched with bursts of lime green, kelly green, and white, the chameleon, locked to its leafy perch by clasping fused toes, is a perfectly adapted predator in the forests of Madagascar. But many Malagasies are not aware of the important role chameleons play in their forest habitat. In fact, island taboos erroneously label them as poisonous creatures, and often they are considered harbingers of bad luck. Still others see them merely as a color-changing novelty and revenue source - much in demand by the largely unregulated international pet trade.

More than half of the world's 100-plus chameleon species live only on the island of Madagascar, and most of them in its forests. But the island is also home to a burgeoning, resource-hungry human population of 12 million, which grows by 3 percent every year. Already, more than 80 percent of Madagascar's native forest has been cleared, felled by chainsaws and axes. And as habitat disappears in this crowded country, which is roughly the size of France, chameleons disappear along with it.

The plight of Madagascar's chameleons is only a microcosm of the pressures facing a vast number of reptiles today. Increased human activities have pushed many of these ancient creatures to the verge of extinction. Worldwide, at least 21 reptile species have completely vanished within the last 400 years - and these are likely only the tip of the iceberg. The 1996 World Conservation Union's (IUCN) Red List of Threatened Animals reports that 20 percent of reptiles for which there "is adequate information to assign a conservation status" are threatened with extinction: 3 percent of these are "critically endangered;" 5 percent "endangered;" and 12 percent "vulnerable."

Many reptiles share the plight of the chameleon, in that they engender intense fear or fascination in people - whether through physical encounters or through the archetypal role they play in the legends and lore of human cultures. Some cultures regard reptiles as powerful religious symbols. The cobra plays a prominent role in Hindu religion, representing Shiva, the god of fertility and death; the plumed serpent Quetzalcoatl was the chief object of worship in Aztec culture, representing fertility, death, and resurrection; the turtle generously agrees to support the earth on its shell in Mohawk and other Native American creation myths; and Australian Aborigines associate a giant rainbow serpent with the creation of life. But perhaps the most telling portrayal of reptiles - reflecting a widely prevalent attitude toward reptiles today - is the serpent described in the Book of Genesis that deceived Adam and Eve, and prompted their fall from innocence. This stigma of reptilian evil has retained a strong grip on the popular imagination, as reflected, for example, in the recent Hollywood film Anaconda, a horror-filled tale of a 12-meter-long, human-eating snake. But today, reptiles have much more to fear from humans than humans do from them.

Reptiles tend to keep low profiles - crouching under rocks, crawling through undergrowth, hiding under water, or perching in trees - and often, especially in the case of research and conservation priorities, out of sight has been out of mind. Unlike birds or frogs, reptiles do not burst into song, and they do not capture the attention of as many biologists as charismatic large mammals do. Consequently, the distribution, ecology, and basic biology of most species remain poorly studied. In fact, the scientists who compiled the Red List were only able to fully assess three of the six reptile orders: the crocodilians, the testudines (turtles, tortoises, and terrapins), and the lizard-like tuataras, each of which ranked high in the number of threatened species - 43 percent, 38 percent, and 50 percent, respectively. But the two largest orders - those of snakes and lizards - were not fully analyzed, nor was the order of legless amphisbaenians. Given these research gaps, and the high number of threatened species in the three fully assessed orders, the Red List's authors surmise that "the overall estimate of 20 percent of reptiles species as threatened is probably low for the entire class."

Although relatively little research has been done to reveal the magnitude of their ecological contributions, reptiles are an indispensable part of many ecosystems - helping to assure the health and stability of their habitats. From clothespin-sized anolis lizards hunting on the walls of Caribbean hotels to eight-meter-long pythons living in the jungles of Southeast Asia, reptiles act as critical links in ecological food chains. We are just beginning to appreciate their roles in regulating pest and insect populations, providing habitat for other species, and maintaining the stability of ecosystems as key predators. For example, in North America, owls, foxes, and rat snakes all prey on white-footed mice, but only the rat snake can crawl into a small burrow to catch a mouse and its young. The rat snake, which is common throughout much of the mouse's range, plays a major role in controlling populations of these abundant rodents.

"Reptiles exert significant control pressure on several other animal groups that pose problems for people, notably rodents and insects," says IUCN crocodile specialist Perran Ross. In overgrown areas, in forests, deserts, and even inside homes in the subtropics and tropics, small lizards such as geckos catch innumerable insects and other invertebrates, helping to curtail disease-spreading insect populations. In South America, the alligator-like black caiman has traditionally curbed populations of rodents called capybaras. But plummeting caiman populations have allowed the capybaras to flourish, which in some areas has caused...