Lizards are probably the most familiar of the reptiles because of their diversity and wide distribution Examples include the ocellated green lizard 1 fat tailed gecko 2 western skink 3 1 blue-tongued skink 4 a sharp-snouted snake Pygopodidae 5 and Colorado checkered whiptail 6 3 4 2 6 5 The emerald boa above is threatened by the destruction of tropical rain forest since it feeds and gives birth in trees Destruction of habitats also removes huge numbers of insects which are an important part of the food chain and support other species of reptile especially lizards Plowing is particularly dangerous to creatures that live in isolated areas of grassland see pygmy blue-tongued skink pp 10 11 and plowing a field could possibly wipe out a whole population of a particular reptile species In addition since many reptiles bury their eggs they are destroyed by such activities Particularly vulnerable are those species that lay small clutches since it is more difficult for population numbers to increase for example Fijian crested iguanas and leopard snakes Farming and industry bring additional threats such as chemical pollution and waste products The effects of pollution are many and varied spraying insecticides for example wipes out the insects on which many lizards rely it can also directly poison reptiles see blunt-nosed leopard lizard pp 8 9 Turtles need clean unpolluted water while some can withstand a degree of certain types of pollution the danger is that the aquatic creatures on which they feed are wiped out Drainage of swamp areas for farming and building forces some species into an ever-decreasing habitat Habitats have become fragmented in many parts leaving a few isolated areas that prevent contact between populations see Jamaican boa pp 20 21 That causes inbreeding which eventually produces weaknesses deformities and reduced fertility in future 6
generations further affecting survival Leisure activities affect reptiles many beaches used by marine turtles for thousands of years for nesting have disappeared under development see hawksbill turtle pp 14 15 Reptiles such as snakes and lizards are sometimes killed to avoid frightening tourists Off road vehicles cause great damage to the burrows and nests of reptiles see gila monster pp 32 33 Hunting and Exploitation Deliberate killing of some reptile species is quite common Many people believe that all reptiles are venomous although very few are in fact dangerous to humans Large reptiles such as alligators and crocodiles can however be dangerous to people and can prey on domestic livestock see Chinese alligator pp 26 27 American crocodile pp 28 29 so they are often killed They have also been regarded as big game and hunted for sport In many parts of the world some reptiles feature in the diet of the native people Where hunting is excessive it can be a serious threat to the survival of a species see Galápagos giant tortoise pp 18 19 Turtle eggs and some lizard eggs are taken for food which combined with other factors causes endangerment Exploitation includes the use of reptile skins and shells Huge numbers of reptiles are used in traditional medicine in various regions the rarer a creature is the more its value The pet trade is often accused of depleting reptile populations This may be true in some cases for example yellow blotched sawback map turtle pp 16 17 but controls on the trade are continually being tightened Despite this smuggling livestock for trade skins food and medicine still occurs in many regions of the world Threats to Island Populations Island populations are highly vulnerable to collection for food see Galápagos giant tortoise pp 18 19 destruction of their habitat see Milos viper pp 24 25 or competition for food see Komodo dragon WHAT IS A REPTILE A crocodile head ashtray This and similar grisly souvenirs are hardly essential to humans but many people are still tempted to buy them Often they are from an endangered creature and it is illegal to sell or import them in many countries pp 12 13 and natural disasters The vegetation of many islands has been eaten by introduced animals such as goats and pigs that escaped and reproduced with devastating results Rats cats and dogs colonized many islands Without any natural predators to keep numbers down they too have taken their toll of reptiles living in restricted island habitats see Jamaican boa pp 20 21 The Situation Today Extinction of some species is part of a natural process but it normally takes thousands or even millions of years Today with the growth of the human population extinction has speeded up and will no doubt accelerate further Although relatively few of the total number of reptile species are listed as Endangered many face similar threats to those that challenge their Endangered relatives Certain species such as the Galápagos land iguana Galápagos giant tortoise pp 18 19 and Komodo dragon pp 12 13 stand out more than others and their plight has made them the focus of well publicized conservation work Conservation attempts will continue but some species will become extinct because of the pressure on their habitats from expanding human populations Zoos and other institutions have limited space and funds and so must limit the creatures they keep Conservation in the wild is also restricted by funds and needs the support of local people It is often difficult to convince people that creatures they fear or dislike are worth saving but attitudes are slowly changing 7
EX EW CR EN VU NT LC Blunt-nosed Leopard Lizard Gambelia sila The decline of this attractive lizard dates back to the California Gold Rush of 1849 when parts of its habitat were turned over to agriculture to feed the influx of miners O the the habitat of the blunt-nosed leopard lizard is now restricted to a number of scattered areas in the San Joaquin Valley in California The lizards use the deserted burrows of small mammals for shade shelter and hibernation in winter Although they are diurnal active during the day leopard lizards tend to shelter during the hottest part of the day They are often active at air temperatures of up to 104ºF 40ºC when the soil temperature is about 122ºF 50ºC From September onward the lizards take to their burrows to spend the colder months in a dormant state Leopard lizards have predators which is part of the natural balance but when the lizards are DATA PANEL so spots become indistinct mated females and juveniles develop orange spots males have red coloration in the breeding season Diet Mainly insects other lizards and small mammals Breeding One clutch of 2 6 eggs laid per year Related endangered species None Status IUCN EN Blunt-nosed leopard lizard Gambelia sila Family Iguanidae World population Probably more than 1,000 adults Distribution San Joaquin Valley California Habitat Arid areas often alkaline saline or sandy soils with sparse vegetation rarely above 2,500 ft 800 m Size Length up to 13 in 33 cm Form Slender lizard with long whippy tail blunt nose and spotted throat variable pattern of dark spots and light bars on yellow fawn gray or dark brown background body color lightens with increased temperatures 8 forced into smaller areas by human disturbance and their vegetation cover is destroyed they become more exposed and vulnerable to these predators The Human Threat As the human population increased in the San Joaquin Valley so did agriculture and urban development This inevitably encroached on the habitat of the blunt nosed leopard lizard Further damage occurred as industries developed around the extraction of oil and minerals By 1985 barely 10 percent of the original wild land on the San Joaquin Valley floor had been left undeveloped and in 2007 the lizard was still thought to be in decline The road building and landfill dumping that accompanied development in the valley were also destructive to the lizard’s habitat and the damage to the delicate balance of the desert ecosystem largely ignored Lizards and their habitats were destroyed under construction machinery roads and irrigation ditches fragmented the lizard’s territory Pesticides sprayed on crops also had a detrimental effect on much of the wildlife Oregon Idaho Wyoming Nevada UNITED STATES Utah Colorado California Arizona New Mexico MEXICO Leopard lizards are insectivorous a large part of their diet includes insects so their food supply can be drastically reduced or contaminated by the drift from crop spraying Where the land has been adapted for pastoral farming grazing animals eat the natural vegetation and
trample rodent burrows and lizard egg sites They also break the soil surface which can cause soil erosion The removal of natural vegetation through grazing allows nonnative plants to invade eliminating the open spaces preferred by the lizard The threats to the blunt-nosed leopard lizard from continuing habitat destruction were highlighted as far back as 1954 but the species was not listed as endangered by the United States Department of the Interior until 13 years later It was given state listing in 1971 Recovery Plans The first recovery plan for the species was not prepared until 1980 revised in 1985 Since then numerous studies have been carried out including aerial surveys to determine the amount of suitable territory still existing Some areas have been purchased as reserves but lack of funding has prevented this in many areas Conservation is a complex business needing comprehensive studies of numerous aspects ecology population feeding habits breeding and genetic variability Although much information has now been gathered the scattered nature of the remaining lizard sites complicates matters because of environmental The blunt-nosed leopard lizard is active by day and prefers hot dry and sparsely vegetated areas It can run on its hindlegs to escape predators which include snakes birds and mammals variation It may be a long time before all the necessary knowledge is accumulated The blunt-nosed leopard lizard has proved itself to be adaptable often colonizing sites that have been disturbed then abandoned However unless the decline of its habitat and its continued isolation in ever shrinking areas are halted the species may never recover Its survival depends on further land acquisition and the construction of corridors to allow groups to move between fragmented sites so preventing the genetic problems that develop in small populations Its habitat must be protected improved and managed in such a way that the land is only used in a manner compatible with the lizard’s existence This is a tall order given the conflicting interests over land use Recovery of this species will take a very long time it remains to be seen if it will be successful 9
