Social Unit Organization in Three Wild Pig Populations

Abstract

Wild pig (Sus scrofa) social unit organization was compared in three introduced populations in the southeastern United States. Group size, age and sex composition and types of social unit were recorded from field observations. Groups of two or more individuals were significantly more frequent than solitary animals in all three populations. Mixed adult/immature groups were the largest social unit of two or more individuals, followed by groups of immature animals and the various types of adult groups. In two of the populations, this same trend among these groups types was seen for the frequency of occurrence (i.e., with the adult/immature group being the most common). In the third population, the frequency of the adult/immature and immature-only groups were reversed. Size variation within all except the mixed-sex adult group type was similar among the three field sites. Adult males were the most frequently observed solitary category. Increased percentage of hardwood forest was significantly correlated with a decrease in the percent frequency of immature-only groups and an increase in adult/immature groups. Increasing annual harvest by man was significantly correlated with an increase in the frequency of immature-only groups and a decrease in those of adults/immatures. The biased removal of females through trapping would be consistent with the apparent shift from adult/immature groups to immature-only groups among the three field sites.