Individual strategies of aggressive and non-aggressive male mice in encounters with trained aggressive residents Benus, Rensina F.; Koolhaas, Jaap M.; Oortmerssen, Geert A. van Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Abstract. To determine whether individual differences in offensive behaviour are related to differences in defensive behaviour, the responses of male wild house mice, Mus domesticus, of an aggressive and a nonaggressive line to defeat by physically stronger residents were analysed. Individuals of the aggressive line engaged in more flight behaviour, whereas the males of the non-aggress!ve line predominantly showed immobility. The higher flight tendency of the aggressive intruders provoked more attacks by the resident, resulting in more fighting between the resident and an aggressive male than between the resident and a nonaggressive intruder. However, if offered an opportunity to escape from the home-cage of the resident, aggressive males more readily made use of it than non-aggressive intruders. Differences between aggressive and non-aggressive male mice are interpreted in terms of fundamentally different behavioural strategies adopted in response to social interaction. The response of aggressive males can be characterized as an active behavioural strategy by which they tend to determine actively their social situation. In contrast, the prevailing lack ofovert attempts to manipulate the situation by the non-aggressive mice points to passive confrontation, in an offensive as well as in a defensive context.