There is, however, a substantial feral population estimated at up to 700,000 in central parts of Australia, descended from individuals introduced as means of transport in the 19th century and early 20th century. This population is growing at approximately 11% per year and in recent times the state government of South Australia has decided to cull the animals using aerial marksmen, the reason being that the camels use too much of the limited resources needed by sheep farmers. For more information, see Australian feral camel.