Disruption of Pairs Produces Pair-Bond Disruption in Male But Not Female Mongolian Gerbils

Previous studies have shown that separating gerbils from established male/female pairs has consequences for subsequent social behaviour. In males, this is characterized by decreased initiation of social contact, social investigation, and either decreased aggressive behaviour or increased defense. In females, there is an increase in immobile-in-contact, which serves to terminate social encounters initiated by another animal. Although these data show the effects of disrupting established pairs, they do not, per se, demonstrate the existence of male/female pair-bonds. Three studies were performed to address this issue in more detail. In the first study, separating females from single-sex groups was found to produce similar effects to those seen following separation from male/female pairs. Generally, opposite effects were seen in males. In the second study, the effects of separating females from male/female pairs were not seen when the original cagemate was replaced with a different animal. These effects persisted in males. The third study revealed that the presence of a female until immediately prior to testing was crucial in producing high levels of social investigation and aggression in males and that the observation of decreases in these behaviours following separation from male/female pairs was dependent on this. Together, these data show that, in males, individual housing is not a critical variable, that effects seen following the breaking of male/female pairs are not attenuated by the presence of a new female, and that these effects are not seen following separation from male/male pairs. It is concluded, therefore, that the behavioural consequences of removing males from established male/female pairs are due to separation from a specific female and that this is highly indicative of the existence of a bonding mechanism in male but not female, gerbils.