Odors in traps: Does most recent occupant influence capture rates for house mice?

Responses of house mice (Mus domesticus) to odors in live traps were studied in a series of eight 0.1-ha outdoor field enclosures. It was assumed that the most recent mouse capture would provide the predominant odor in a trap for at least one week. Three different populations were tested, one in 1989 and two in 1992, involving over 800 different mice. Similar response patterns were recorded from all three groups. Two types of questions were tested: (1) Were there any biases contingent upon what had been previously caught? (2) Were there consistent responses of mice of particular age, sex, or reproductive classes to trap odors? Traps soiled by juvenile females caught adult females significantly less often than expected, but there were no consistent relationships in terms of the effects of specific residual odors on the subsequent capture at a particular trap. For various age, sex, and reproductive classes, (1) adult males preferred odors from juvenile and estrous females and avoided odors of other males significantly more than expected, (2) juvenile females selected traps with odors of other juvenile females and avoided all other types of female odors significantly more than expected, (3) nonestrous females exhibited a significant preference for adult male odor, and (4) estrous females selected traps containing odors from adult males but avoided those that had previously contained either nonestrous or pregnant/lactating females significantly more than expected. These findings have potential implications with regard to both the methods used for trapping small rodents and the social biology of house mice.