Although population size is one factor affecting the intensity of wildlife damage, the relationship between damage and population size is unclear. We propose a new hypothesis that: the open land preference affects the intensity of crop damage. We defined the open land preference based on the behavioral traits of each individual showing dependence on farmland. If the open land preference of a population increases, crop damage increases because individuals with a high open land preference frequently use farmland. Based on ethological perspectives, this hypothesis assumes population ecology and ethology best explain damage by wildlife. We used long-term wildlife camera trap data collected from orchards. These data confirmed increased rates of damage from sika deer (Cervus nippon) were higher than the population growth rate. Initially, wildlife mainly used farmland at night during the summer, but gradually the deer changed their farmland-use patterns to other seasons and during the day. These results indicated: i) the increasing rate of damage from deer could not be explained by population size alone and ii) increased damage was accompanied by a behavioral change in deer. This behavioral change corresponds to the change in the open land preference and the data supported our hypothesis.