Environmental correlates of nest site selection by wild boar Sus scrofa

Location of nests, built by free-living wild boars Sus scrofa Linnaeus, 1758, was analysed in order to assess the importance of environmental and social conditions in piglets' survival during the first days after birth. The research was carried in a Mediterranean forest with different habitats and high density of natural predators. The results indicate that most nests were already constructed before the beginning of March, being located preferentially in areas with: (1) abundant plant cover, (2) water nearby and (3) a warmer temperature than in other places. These results suggest that female wild boar try to diminish mortality caused by natural predators by constructing their nests in places with dense cover. Water is very important because of the females' new necessities derived from milk production. Warm nesting places might diminish deaths after birth in a species with important thermoregulation deficiencies. The distance between nests is also important because in this period the wild boar develops a territorial behaviour, possibly with the objective of establishing bonds between the mother and her offspring before returning to the familiar units made up of several females and their piglets, all of them of a similar age.