Scent counter marks: selective memory for the top scent by golden hamsters

Animals often scent mark where other conspecifics have marked, a pattern of behaviour called counter marking. Despite the generality of this behaviour, little is known about the functions or perception of counter marks. A series of experiments using an habituation technique was conducted to investigate what information male golden hamsters, Mesocricetus auratus, remember after they investigate partially overlapping scents of two other individuals. Five experiments were carried out using vaginal secretions of female hamsters as the stimuli and one experiment used male flank gland scents as stimuli. Counter to expectations, all experiments indicated that hamsters remembered the top and/or most recent individual scent and did not remember the bottom and/or older scent. These results indicate that hamster selectively remember just one of the two scents, the top one, and imply that hamster have previously unsuspected mechanisms for determining which individual scent is on top. The strategy of remembering the top or most recent individual scent may be an adaptive means of dealing with a complex array of social scents.