Camels, weeds and ecosystem service

My 1st reaction to this story is that the camels provide ecosystem service of biological control. But wait a second, camels are invasive species themselves, aren't they? So we are using one invader to control another, although these camels for sale were probably not feral. Still can we make sure these big fellows are only going to nibble weeds not native species? How selective are they? According to this document though, they don't have big impacts on native species or water supply unless we have a drought.

Um, drought, that is another word we hear a lot these days.