Sika deer (Cervus nippon) cause serious damage to trees in Japanese forests. Browsing, bark stripping, and tree abrasion with antlers account for 50% of total wildlife damage over the past decade. The extent of forest damage depends on deer population density. We determined the spatial distribution of sika deer population density on Mt. Hiko (Fukuoka Prefecture, southwestern Japan). We also investigated changes in population density distribution over time. Determinants of population density were examined, with particular emphasis on the hunting cull. Deer densities in 1999 and 2004 were estimated by fecal pellet counts at 86 sites. We used kriging, a geostatistical technique that is a component of geographic information systems, to interpolate site-specific point data over large areas of landscape. Mapping procedures showed that high-density (≥30.0 deer km−2) and low-density sections of landscape (≤10.0 deer km−2) decreased in areal extent between 1999 and 2004. Contractions of high-density sections were attributable to intensive hunting. In low-density landscape sections, reduced hunting pressure allowed increased persistence of adult animals whose high fecundity led to population growth and higher deer densities. Landscape tracts with medium deer densities (10.0–30.0 deer km−2) expanded, adding further difficulties to the task of wildlife management. Given the scale of the problems caused by deer, it is clear that reliable estimates of population size across space and time are essential components of the wildlife manager's toolbox.