Spatial variation in local population dynamics of sika deer, Cervus nippon, through intensified management

Abstract

Population reduction through hunting and nuisance control has been practiced in many parts of the world to prevent an overabundance of ungulates; however, there is limited knowledge regarding the quantitative impact of intensified hunting management and nuisance control on local dynamics within managed populations. This study examined spatial variations in the local dynamics of sika deer (Cervus nippon) along with hunting and nuisance control across 256 mesh units (23 km²/mesh unit) within the Kushiro subprefecture of Hokkaido, Japan, from 1994 to 2020 (27 years). Under enhanced management, the population declined twice but only by about 14% from the previous peak each time. Since 2017, however, the population has remained stable without further decline. Local densities ranged from 1 to 120 deer/km² within the area, with higher densities producing higher harvest rates (i.e., density-dependent harvesting). Temporal trends in local densities varied across the mesh units: in some mesh units, sika deer at a high density (≥50 deer/km²) consistently decreased by more than half, whereas in others, medium densities (25–50 deer/km²) increased following temporal fluctuations, and low densities (<25 deer/km²) remained stable throughout the same period. Thus, the extent of human-induced population reduction locally differed and was likely larger at high-density mesh units. Consequently, the impact of intensified management at the prefecture scale varies locally. Therefore, allocating management efforts to high-density mesh units is preferable for more efficient population control across the entire area.