As herds of the beautiful and endangered Tibetan antelope arrive after a long migration to give birth in Tibet's Hoh-Xil National Nature Reserve, rangers safeguard against illegal poaching by implementing an invisible surveillance network that allows them to monitor the entire reserve without disturbing the animals.

http://english.cntv.cn/program/china24/20110615/103474.shtml
http://www.bjreview.com.cn/special/2011-06/16/content_367873.htm