Wild pigs are gregarious, forming herds or 'sounders' of varying size depending on locality and season, but usually of between six to 20 individuals, though aggregations of over 100 have been reported (34). The basic social unit is a nucleus of one or more females and their last litters. The female-dominated sounders consist of barren sows and mothers with young led by an old matriarch. Male boars leave their sounder at the age of eight to 15 months, while females either remain with their mothers or establish new territories nearby. Sub adult males may live in loosely knit groups, while adult and elderly males tend to be solitary outside the breeding season. However, the latter tend to stay in relatively close contact with one or two female groups at other times of the year, and sub adult males or mixed sex groups of sub adults may also form longer-term associations.