This paper analyses the temporal variation in the size of home range and activity of adult wild boar (Sus scrofa L.). Eighteen boar were radiotracked between 1991 and 1993 in the Maremma Natural Park (Central Italy). Variations of home-range size and activity were related to sex, winter food availability and population density. The hypotheses that home-range size was inversely related to food availability and population density, and that the amount of activity was directly related to population density and inversely related to food abundance, were tested. The size of the acorn crop was used as a measure of winter resource level. No differences were found in the size of ranges, core area, and activity between males and females. In 1991-92 home-range size was larger than in 1992-93; conversely, activity increased from 1991-92 to 1992-93. Winter food availability was high in 1991-92 and low in the following year. Population density increased greatly in spring 1992 but crashed in spring and summer 1993, when a high mortality of wild boar occurred due to starvation. The decrease in home-range size during the food shortage was explained as a possible strategy adopted by wild boar to cope with starvation. The difference in home-range size and amount of activity found between the first and the second year of study were probably influenced by differences in population density, although the individual effects of food availability and population density were not clearly separable.