Australia's mulga country, or bush, is a dense woodland of acacias, ghost gums and bloodwoods, all rooted in the outwash of the Central Ranges. Most woody shrubs are thirsty and demanding but these tough plants have flourished despite the dry soil and some unwelcome invaders. In the 1880s, camel trains were the only way to cross the desert. But once roads were built, the camels were abandoned and are now feral. With no natural predators they have thrived here and Australia is now the only country where one-humped camels live in the wild. In the breeding season males do their best to mate with as many females as they can. They do this by frothing at the mouth and inflating their dewlaa - a sac on the roof of their mouth. It looks grotesque, but it is obviously attractive to the females and intimidates other males. When two bulls fight, it can get very serious as they use their necks to try wrestle each other to the ground. Over half a million camels now roam the Central Ranges and they are now considered serious pests.