updated 5/17/2011 4:18:01 PM ET 2011-05-17T20:18:01        Since
then their population has doubled every eight or nine years.
"They are desert-adapted animals," explained Ferguson. "They
adapt very well to our conditions."  The camels can chug more
than 50 gallons of water in three minutes and their thirst often
leads to problems. Sometimes when large numbers of feral camels
converge on a small waterhole, the first animals get mired in
the holes and die, fouling the water and destroying the
waterhole completely. These waterholes are critical resources
for humans and native birds and animals.  "There's no way you're
ever going to eradicate them," said Murray McGregor of Curtin
University in Perth, whose research estimated their numbers.
"The key thing is to keep the number controlled to minimize the
environmental and cultural damage."  The camels are spread over
a 3.3 million square kilometer (nearly 1.3 million square mile)
area. McGregor's work estimated that more than 40 percent of the
camels are on Aborig