Effect of distance from farm periphery on the risk of forage damage by sika deer (Cervus nippon)

The foraging behavior of deer can be influenced by both food availability and the " critical distance" from protective vegetation cover. The effect of the distance from the farm periphery on the risk of forage damage by sika deer was investigated in a public pasture in Tochigi Prefecture in central Japan from May to November 2006 and in May 2007. The risk of forage damage by sika deer, evaluated by deer pellet group density, was compared along three line transects at different distances from the farm periphery (10, 110 and 210 m) and among 18 paddocks at different distances from the farm periphery. Deer pellet group abundance in the line transects did not differ significantly with the distance from the periphery but decreased significantly with the distance from the nearest escape cover. The transect-based deer pellet abundance was more significantly influenced by other factors such as paddock identity and survey month in a generalized linear model. Deer pellet group abundance in the paddocks showed a significant albeit weak negative correlation with distance from the periphery in May 2007, but not in November 2006. The paddock-based deer pellet abundance was more influenced by sward height than by the distance from the periphery in a generalized linear model. Furthermore, a high density of deer pellet groups was exclusively observed in the paddock just after pasture renovation. These results show that the foraging behavior of sika deer was influenced partially by the distance from the nearest escape cover but largely by other factors such as herbage quality and seasonality.