as a number of the desert's animals, including the southern marsupial mole (Notoryctes typhlops), and the water-holding frog do. Reptiles live in large numbers in the deserts, for example the thorny devils, bearded dragons, monitor lizards, frilled dragon and geckos. Frog species that have adapted to drought, such as the Desert Trilling Frog (Neobatrachus centralis) and the Desert Tree Frog (Litoria rubella), can also occur. The most numerous species of lizards in the world can be found in the Australian desert, there are over 40 species of them there. In addition to fish, the few permanent freshwater holes are also home to mussels, crustaceans and insects. 34 species of fish occur in Lake Eyre and others at the artesian springs (e.g. at Dalhousie Springs in South Australia). Over 40 species of frogs have been observed after heavy rains. The Dingo Fence was built to restrict movements of dingoes and wild dogs into agricultural areas towards the south east of the continent. Predators of the desert include the dingo (as the desert is north of the Dingo Fence) and two large monitor lizards, the perentie (Varanus giganteus) and the sand goanna (Varanus gouldii). Many introduced species have affected the fauna and flora of Australia's desert regions. The Australian feral camel affects native vegetation, partly because Australian desert vegetation evolved without any major herbivores present. Uncontrolled access to more sensitive areas by four-wheel-drive vehicles is also an issue. Feral cats have reduced the populations of bilbies and mulgara. Climate Australia's climate is mostly determined by the hot, sinking air of the subtropical high-pressure belt (i.e. Australian High). Dry conditions are associated with an El Niño–Southern Oscillation in Australia. Vegetation in arid areas is primarily dependent upon soil type. The average annual rainfall in the Australian desert ranges from 81 to 250 mm (3 to 10 in), which would make it a semi-arid climate. But a massive evaporation rate makes up for the higher than normal desert rainfall. Central Australia is arid, with the driest areas averaging of rainfall each year. Thunderstorms are relatively common in the region, with an annual average of 15 to 20 thunderstorms. Summer daytime temperatures range from 32 to 40 °C (90 to 104 °F); winter maximum temperatures average between 18 to 23 °C (64 to 73 °F), though will be more warmer in the north. Extensive areas are covered by longitudinal dunes. The northwestern region of the