Optimal unmanned aerial vehicle (UAV) height and sampling area for aerial photography-based survey of the Manchurian zokor population

• SUN Shanshan, 
• Manduhu, 
• Weijun, 
• Chaoketu, 
• Ayan, 
• ZHANG Heng, 
• FU Heping, 
• WU Xiaodong, 
• YUAN Shuai