Highlight Measuremenis and their sfafisfical analysis are suggested and fesfed in the study of sheep distribution in an arid pari of Australia. The use of aerial phoiography and an elecironic compuier make fhe job possible and relatively cheap. The possibility of predicting fhe condifion of a range from patterns of grazing behaviour is suggested. 1 The work would not have been possible without the generous help and personal interest of Mr. Tedd Marr, the owner of Mt. Murchison and Messrs. Frank and Brian Clark, owners of Kayrunnera. We wish to acknowledge also, the skilful photography of Mr. C. Totterdell and precision flying by Mr. H. Debney of Barrier Air Taxis Ltd. Messrs. I. G. Bush and H. Simpson, and Mrs. R. Jarasius are thanked for technical assistance.