Somewhere in the boundless desert in the eastern part of the Xinjiang Uygur autonomous region, a railway flyover spans a highway. Underneath the rails, but above the road, there is a "land bridge" 100 meters wide, specially built for wildlife to be able to safely cross the expressway.

There are two such constructions over the 515-kilometer expressway section connecting Wutongdaquan in Hami and Mulei Kazak autonomous county, as well as 60 road bridges and downslopes for wild animals.

Eighteen months after this section came into service, Mongolian wild asses and goitered gazelles can be seen traversing the overpasses and underpasses with ease.

This section is part of the G7 Expressway, connecting Beijing and Urumqi, the regional capital in Northwest China. It's the longest stretch of desert expressway in the world.

"Based on field research and monitoring data from infrared cameras, we can say that large- and middle-sized wild animals have gradually become accustomed to the wildlife passages," says Li Weidong, 67, wildlife protection expert.

He has led a program that provided consultation before and during the expressway construction, and monitored wildlife activities since its completion. During the process, he and colleagues from an NGO he initiated have also investigated the distribution and number of common species in the area, especially the ungulates.

In the 1980s, it was Li who discovered and named the Ili pika. Since then, the former public health expert has turned his career focus to wildlife protection. As he himself has put it, he "has served as a spokesperson for wild animals "for four decades.

He has joined protection programs for the Ili pika, Tibetan antelope, Camelus ferus (wild camel), and Mongolian wild asses, among others, and over the years has been consulting on, and delivering environmental impact assessments of, major construction projects in the region.