BEHAVIORAL STRATEGIES OR JUST INDIVIDUAL VARIATION IN BEHAVIOR - A LACK OF EVIDENCE FOR ACTIVE AND PASSIVE PIGLETS

We criticize the recent paper by Hessing et al. (1993, Appl. Anim, Beh av. Sci., 37: 285-295), where it is concluded that there are ''consist ent individual behavioural strategies in social and nonsocial situatio ns in pigs'', resembling the active and passive coping strategies of m ice. We argue: (1) The authors have not demonstrated that the underlyi ng distributions of individuals deviate from a normal distribution. Th us the existence of two distinct types of individuals is a premise of the research and not a conclusion. It is arrived at by choosing arbitr ary cut-off points. (2) The social test used is not suited for determi ning individual characteristics, and the so called back test is diffic ult to interpret. It has not been verified that the back test is a non -social test. (3) The two-way classification based on these two tests excludes a substantial proportion of the piglets. We conclude that the authors provide no evidence for distinct individual types of piglets.