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

The traditional methods used for surveying underground rodent populations, such as the manual trapping and mound counting methods, are time consuming and labor intensive. Aerial photography by an unmanned aerial vehicle (UAV) is a flexible, easy-to-operate technology that can realize the dynamic analysis of ground data and aerial images. In this study, UAV-facilitated aerial photography, conducted at different flight altitudes and shooting areas, was used to investigate the density of ground mounds of Myospalax psilurus at 13 representative locations in the meadow grasslands of Hulunbuir. In combination with a manual ground survey of the mound numbers, the aerial images were visually interpreted to determine the number of mounds and to analyze the best aerial height of the drone. The relationship between the aerial photography area and the mound density was analyzed, and the minimum sampling area for the UAV investigation of the M. psilurus ground mounds was clarified. The results indicated that for investigating the relative population of M. psilurus in the meadow grasslands of Hulunbuir, the best aerial photography height of the drone is 50 m and the minimum sampling area is 2.21 ha.