THE RESPONSE OF SUBORDINATE MALE-MICE TO SCENT MARKS VARIES IN RELATION TO THEIR OWN COMPETITIVE ABILITY

Previous work has shown that dominant male mice, Mus musculus, are usu ally attracted to scent-marked areas while subordinates avoid them. In this study, the responses of subordinates were highly variable, and t he idea that the probability of intruding onto a scent-marked substrat e depends on their competitive ability was tested. Subjects were kept in dominant/subordinate pairs of males and tested with scent marks of an unfamiliar male. Subordinates who were large in relation to their d ominant partners were more likely to choose a scent-marked substrate i n a Y-maze choice against a blank substrate; relatively small subordin ates were more likely to avoid scent marks. Males that chose scent mar ks also tended (P=0.08) to be more often involved in escalated contest s with their dominant partners. Body size is known to affect the outco me of fights between strangers and these results could be explained if relatively large subordinates are (1) more likely to be able to defea t the resident of a scent-marked area (and thus benefit from its resou rces) and (2) if large subordinates pose a greater threat of a dominan ce reversal to their dominant partners than would a relatively small s ubordinate. (C) 1996 The Association for the study of Animal Behaviour