Assessment for the wildlife crossing structures along the Qinghai-Tibet railway

Previous Qinghai-Tibet railway studies have lacked a comprehensive understanding of wildlife crossing structures (WCSs) distribution and suitability for local wildlife, focusing instead on individual underpass usage. We addressed this gap by modeling the habitat distribution of 11 nationally protected mammal species along the railway using maximum entropy modeling and distribution data, and we found that WCSs density met standards for all species except Tibetan gazelles (Procapra picticaudata), whose average WCSs distance was 1.65 km. After evaluating 23 underpasses with line transects and infrared cameras, we found that all underpasses were used by wildlife, with nine protected mammals recorded, while Tibetan antelopes (Pantholops hodgsonii) used exclusively larger underpasses during migration. Smaller underpasses located further from highways were more effectively used. This first assessment of WCSs distribution and density along the railway, comparing large and small WCSs, recommends prioritizing larger WCSs construction tailored to Tibetan antelope migration needs in future designs.