Comparison of the Spatial Distributions of Sika Deer (Cervus nippon) Detected by Light Census and Aerial Photographs Taken by Drone

Abstract

The recent rapid increase in the number of sika deer (Cervus nippon) and the expansion of their habitat has caused serious damage to the forest ecosystem. In order to reduce the damage caused by deer, population reduction and physical control could be considered. For this purpose, knowledge of the population in target areas is important. However, it is difficult to estimate the population in such areas by conventional methods such as a light census. Therefore, development of new population estimation methods is needed. In this study, we compare the spatial distribution and number of sika deer in Ozegahara detected by light census and aerial photographs taken using a drone to contribute to the above-mentioned objective using a remote sensing technique. Results showed that although the survey efficiency of the light census was higher than that of the drone, the number of deer detected by drone was more than four times higher. This was because the light census could not detect deer in places far from the boardwalk. In contrast, aerial photographs could detect the deer in any place. Thus, aerial photographs taken by drone may play an important role in monitoring deer populations in places, such as Ozegahara, where it is difficult to apply a light census to the whole area.