The pilot was operating on a Search and Rescue watch manned from the homestead. When the aircraft did not arrive by the appointed hour, the owner of the station conducted an aerial search and found the pilot by the disabled aircraft. The pilot reported that he was attempting to land beside the portable cattle yards when he backed off to avoid the dust clouds thrown up by the main rotor. In doing so, the tail rotor struck a tree obscured by the dust. An immediate landing was initiated but a heavy touchdown resulted. The tail rotor blades separated from the aircraft before the engine was stopped and the tailboom and skids were twisted from the impact with the ground.