THE PRIMING EFFECTS OF URINE SUBSTRATE MARKS ON INTERACTIONS BETWEEN MALE HOUSE MICE, MUS MUSCULUS-DOMESTICUS SCHWARZ AND SCHWARZ

Abstract. Behaviour during encounters between males within captive populations of wild house mice was analysed to test whether mice advertise local dominance through urine substrate marks to avoid costly interactions when two males meet. Small quantities of urine from familiar residents, neighbours and unfamiliar males of dominant or subordinate social status were introduced onto naturally established urine posts. Introduced urine differentially altered behaviour between dominant territorial males, intruders and resident subordinates, producing complex patterns of change which were in agreement with predictions. The familiarity and social status of a urine donor were important factors in determining the priming effects of marks on individual behaviour. Intruders and resident subordinates normally fled from resident territory owners before they were attacked but failed to anticipate attacks from other aggressors. Marks from familiar residents and neighbours induced specific changes in differential evasion in the vicinity of the marks. Subordinate male urine increased a resident dominant male's aggression against the urine donor, while marks from unfamiliar subordinates increased aggression between other males. Urine from unfamiliar males altered behaviour towards familiar males of equivalent social status, suggesting some generalization of response or difficulty in distinguishing between odours from mice of similar status. This system appears to provide mice with up-to-date information concerning dynamic shifts in individual dominance and territory location. Individual males use this information to avoid a marked area, to evade a male likely to attack, or to challenge the dominance of a competitor, according to their own status and previous experience.