Endangered Reptiles woodland and scrub to create agricultural land has been the major cause of population declines among snakes Declines among reptiles as a result of deforestation have been particularly marked on Madagascar Roads present a particular risk to reptiles, not only because they have to cross them as they move about, but also because they are attractive places to bask in the sun Large numbers of snakes, tortoises, and lizards are killed on roads In some turtles, females are at greater risk than males, apparently because they move about more than males Animals of all kinds that live on small oceanic islands are especially vulnerable to extinction, and reptiles are no exception Island species are often very vulnerable to introduced predators, such as rats, cats, dogs, and mongooses, having evolved in an environment in which such predators were previously absent Small islands are also highly susceptible to habitat destruction and excessive hunting Among endangered reptiles that live on islands are giant tortoises such as those found on Aldabra and the Galapagos Some reptiles are vulnerable to exploitation by humans and to natural predation because they gather to breed in large numbers A marine turtle, Kemp’s ridley (Lepidochelys kempi), was reduced to near extinction in the 1970s by the commercial exploitation of breeding females and eggs, gathered at their coastal breeding sites in Mexico and Texas This species is now internationally protected and its numbers are recovering Migratory species, such as some sea turtles, are very vulnerable both because their conservation requires that they be protected in several, often distant, parts of the world and because they have to make long journeys across possibly hazardous environments The green turtle (Chelonia mydas), for example, is protected in Australia but is exploited in Indonesia Leatherback turtles (Dermochelys coriacea) nesting in Gabon in central Africa undertake huge journeys across the Atlantic, to South America or to southern Africa Satellitetracking has revealed that one female leatherback traveled 7563 km between a feeding area off South America to her nesting site in Gabon (Witt et al., 2011) Such long journeys take turtles through many areas where they are in danger of being caught by fishermen As a result, their effective conservation would require active cooperation by at least 11 different nations Commercial Exploitation Throughout human history, reptiles have been used by people for a variety of purposes Apart from being a food source, tortoise shell is used for decorative purposes Snake, lizard, and crocodile skins are used to make shoes, belts, and handbags, and the flesh of many reptiles is believed to have medicinal or aphrodisiac properties In some parts of the world, there is also a substantial trade in reptile meat Between 1979 and 1987, the hunting of alligators in Louisiana yielded 45,000 kg of alligator meat each year Many turtles are heavily exploited as a food source, both by indigenous people and the markets in developed countries to supply luxury food In Asia, the trade in turtles for food and medicines has reached crisis proportions, with 67 of 90 species categorized as threatened and 18 as critically endangered 217 The green iguana (Iguana iguana) has declined severely as a result of being hunted for food Eaten by humans in Central America for centuries, destruction of its habitat and the expansion of the human population have led to it being hunted much more intensely in the past 30 years In the late 1960s, as many as 150,000 iguanas were eaten each year in Nicaragua alone Not only is iguana flesh regarded as a great delicacy but also their fat and eggs are used for a variety of medicinal purposes, including a cure for impotence The adverse effects of the overexploitation of natural populations can, in some cases, be countered by sustainable farming There is now a thriving trade in American alligators (Alligator mississippiensis) with more than 30 farms in Florida providing more than 136,000 kg of alligator meat and 15,000 skins each year The highly durable skin of reptiles makes it an excellent alternative to leather, and reptile skins have long been used for making footwear, purses, belts, and many other accessories Many species of pythons, boas, varanid lizards, and crocodiles are declining because they are hunted for their skins In 1981, the USA imported 304,189 pairs of shoes made from boa skin and 176,204 pairs of python skin shoes In the absence of commercial breeding programs for these species, this trade was entirely based on the exploitation of wild populations Today, trade in reptile skins is increasingly regulated and sustained by breeding animals in captivity, but there remains a substantial illegal market in skins derived from natural populations Products derived from reptiles and amphibians are constituents of many traditional medicines and are used in many other ways Broths made from snakes and tortoises are believed to combat many diseases; the fat of monitor lizards (Varanus spp.) is used to combat skin infections; sea turtle eggs are used as aphrodisiacs; turtle oil is used to make perfumes and lubricants Introduced Species As the human population has expanded and people have colonized new parts of the world, they have taken with them, deliberately or accidentally, a variety of organisms that have been harmful to indigenous wildlife This is a particularly serious threat to species living on small islands where, in the absence of indigenous predators, they have lost their defense against predators Populations of many reptile species that are endemic to islands have been devastated by the introduction of alien rats, cats, dogs, and other animals that feed on them or their eggs, and introduced pigs and goats have destroyed the ground cover that supports their food supply and which they need to escape from predators The tuataras (Sphenodon) have become extinct on the two major islands and on many of the smaller islands of New Zealand and are now confined to a very few small islands that remain free of alien immigrants Intensive efforts are now being made to clear other islands of predators and prevent further releases of alien species In addition, tuatara eggs are being incubated in captivity and the resulting lizards are being released across the various protected islands in such a way as to maintain genetic diversity in these small populations (Keall et al., 2010)