DIET AND CONDITION OF WILD BOAR, SUS SCROFA SCROFA, WITHOUT SUPPLEMENTARY FEEDING

From 1987 to 1992 diet and condition of two populations of wild boar which received no supplementary feeding were studied in the Veluwe area, a large area of heathlands and forests in The Netherlands, and were compared with those obtained in a previous study (1974-1976), when supplementary food was provided. Composition of stomach contents depended mainly on season, mast availability, and area-specific factors, whereas sex and age were of little or no importance. Density dependence was found for the decrease in mast (tree seed) consumption from autumn to winter. In autumn, and in winters of rich mast years, mast was the main constituent of the diet. In winters of poor mast years this was replaced by broadleaved grasses in one area and by broadleaved grasses, wavy hairgrass, and roots in the other. We found no important differences between the stomach contents of animals receiving no supplementation, and the natural fraction during a period of supplementary feeding. Variation in body weight was related mainly to age and sex, but also to mast availability. Judged by relative loss of body weight and decrease of bone marrow fat, juveniles seemed to suffer more from poor mast availability than adults. The decrease in body weight from autumn to winter was greater when population density was high. In poor mast years, recruitment into the population receiving no supplementation depended on the availability of broadleaved grasses; in rich years, recruitment was still lower than in populations receiving supplementary feeding. In populations receiving supplementary feeding, recruitment seemed independent of mast availability.