The behaviour of free ranging pigs in the Mexican tropics and its relationships with human faeces consumption

There is no information on how free ranging pigs in the Mexican tropics distribute their time during the day and how these time budgets relate to their age and social behaviour of the pigs. It is known that in these areas pigs consume human faeces, which constitutes a serious public health problem as it maintains the life cycle of Taenia solium. The study was carried out in a community of the state of Guerrero, Mexico, where five groups of free ranging pigs were observed during the dry and rainy seasons. A combination of scan and behaviour sampling was carried out to obtain information on time budgets and social interactions of adult, sub-adult, and juvenile pigs. On average the pigs spent significantly more time feeding and in locomotion during the rainy season (12.0 and 25.2%, respectively) than during the dry season (5.9 and 13.6%, respectively). Also, they spent more time resting and exploring during the dry season (69.2 and 11.2%, respectively) than during the rainy season (56.9 and 5.0%, respectively). The frequency of human faeces consumption was higher during the dry season. In both seasons the leaders of the groups, which were usually adult females, ate human faeces significantly more frequently than other pigs. On average, the pigs walked less than half the distance during the dry season than during the rainy season. In general, the frequency of non-agonistic interactions was higher than agonistic interactions in adult, sub-adult, and juvenile pigs. Adult sows were socially the most active group as they performed agonistic and non-agonistic interactions more frequently than other individuals. The interactions within age groups were more frequent than between groups. This information is useful to improve management practices of these pigs in the Mexican tropics as well as to better understand individual susceptibility to infection by T. solium as well as to how they acquire immunity to that parasite. (C) 2004 Elsevier B.V. All rights reserved.