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 examined the nature of this knowledge in golden hamsters, Mesocricetus auratus, using habituation-discrimination techniques. Male hamsters were first familiarized with two females; they were later habituated to one type of odour (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 odours (vaginal secretions, flank gland and ear scent). This effect did not occur if the males had not been familiarized with the female scent donors. These results show that males generalized between two scents from the same individual, presumably because the two odours had the same meaning. The results suggest that males formed integrated, multicomponent representations of females. Additional experiments showed that the cross-habituation effect requires interaction between individuals; mere exposure to the odours of an individual in its home cage is not sufficient. Cross-habituation between different 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 species because of selection for conservation of water. (C) 2001 The Association for the Study of Animal Behaviour.