Every year Hoh Xil, in the northeast corner of the vast Qinghai-Xizang Plateau, witnesses the annual migration of Tibetan antelopes. To ensure their safe passage across the Qinghai-Xizang Highway, rangers from the Wudaoliang Conservation Station carry out strict traffic controls and impose a ban on car horns. Sometimes it could be a test of the drivers' patience to wait for the suspicious antelopes to cross, as it could take a  dozen trials back and forth before they eventually make it.