| Summary: | Three experiments were conducted to investigate possible effects of rearing litters of gerbil pups to weaning in the presence of an adult male. The first experiment found animals reared without the male to be heavier than those reared with the male. There were no differences on one-day open-field behaviour, but in paired social encounters in a neutral arena those reared without the male spent less time in mutual contact. A second and more complex experiment was completed after many vicissitudes, and the weight difference was confirmed. With five days of open-field testing significant group differences on activity measures, but not on defaecation, suggested the importance of the presence of the male in the first week after birth. These differences were maintained in subsequent weekly tests which incorporated an examination of ventral scent marking, although this was not affected. The direction of the differences, especially of effects of litter size in Experiment 1, suggested that the mechanism involved was that of the maintenance of nest temperature. The interpretation of the open-field results occasioned a general discussion of the test and of the emotionality concept. The third experiment was similar to the first in design, but it did not confirm the previous effects on body weight. The direction of group differences on rearing in weekly arena tests and in social behaviour tests reversed those found previously. These problems may have reflected small procedural and situational differences but without further experimental work they must cast considerable doubt on the original findings. In view of these problems a final experiment pursued previous investigation of social behaviour, using home-cage residents faced with various intruders rather than neutral arenas. Mutual sniffing showed some differences over the subgroups of the experiment and differed from patterns of investigation in neutral arenas. As in previous experiments on social behaviour the low level of aggression between adults contrasted with the literature on other rodents; however here juvenile intruders were attacked more often, this was discussed in terms of possible dispersal mechanisms in natural populations.
|
|---|
