In one study, using a habituation procedure, male South American cavies,Cavia aperea, distinguished individual differences in odors collected from three sources: perineal gland secretions, urine, and supracaudal gland secretions. In a second study, male cavies spent more noninvestigatory time and rested more on the side of a cage containing the odor of a familiar subordinate male as compared to the cage side containing the odor of a familiar dominant male. Since the odor source was a glass plate which had been left in the home cage of the donor males for three days, the actual odorous cue to which the test males responded is not known. These studies demonstrate that male cavies distinguish odors of individuals, that individual differences in odors are found in at least three different sources, and that cavies use chemical cues to distinguish between known individuals.