Evaluation of three monitoring methods for sika deer population density: block count, pellet group count and sighting per unit effort

Abstract

Indices of population density are important for management of the sika deer Cervus nippon. However, no investigation method appropriate for the steep and bushy forest of western Japan has been established. We compared consistency among three indices of relative deer density, which have been adopted by several prefectural governments in midwestern Japan, including the block count method, the pellet group count method, and sighting per unit effort (SPUE). There were strong positive correlations among them. Annual changes of pellet group density and the SPUE were highly correlated. So the pellet group count method and the SPUE were effective for evaluation of population trends. However, the pellet group count method was influenced by temperature in investigation periods, and the SPUE was also influenced by the quantity of harvest data and the investigation season. Therefore, it is necessary to use multiple indices of the relative density of deer for the appropriate evaluation of population trends.