Individual recognition by use of odours in golden hamsters: the nature of individual representations

Although much is known about individual recognition, little is known about the representations that individual animals have of other individuals. We e xamined the nature of this knowledge in golden hamsters, Mesocricetus aurat us, using habituation-discrimination techniques. Male hamsters were first f amiliarized with two females; they were later habituated to one type of odo ur (vaginal secretions, flank gland, urine or ear scent) from one of these females and tested for cross-habituation (generalization) to another odour from the same female. Cross-habituation was shown across three of these odo urs (vaginal secretions, flank gland and ear scent). This effect did not oc cur if the males had not been familiarized with the female scent donors. Th ese results show that males generalized between two scents from the same in dividual, presumably because the two odours had the same meaning. The resul ts suggest that males formed integrated, multicomponent representations of females. Additional experiments showed that the cross-habituation effect re quires interaction between individuals; mere exposure to the odours of an i ndividual in its home cage is not sufficient. Cross-habituation between dif ferent odours did not occur when urine was used as one of the stimuli, even though urine was individually distinguishable. We suggest that the reason for this is that urine is too costly to be used for communication in this s pecies because of selection for conservation of water. (C) 2001 The Associa tion for the Study of Animal Behaviour.