Sex differences in the behavior and the social interactions of immature Galago senegalensis braccatus.

There is little detailed documentation of immature behavior, especially mother-offspring interactions, for nocturnal prosimians, and few studies have examined sex differences in mother-offspring interactions. This study compares the behavior of captive-born Galago senegalensis braccatus, the Senegal galago, from 1 to 20 weeks of age for 3-5 females and 4-6 males. The subjects lived in social groups, on a reversed light cycle. Three 10-min focal samples were taken each week, for each subject, during each of the 6 most active hours of the waking cycle (night). Locally weighted regression scatterplot smoothing analysis was used to test for sex differences in behavior. There were no sex differences in most forms of mother-offspring contact, including nursing, control of proximity with the mother or grooming. Females were more active than males in the rate of solitary acrobatic play and, only after the age of weaning, in locomotion. Altogether, these observations suggest that the sexes might not present more energetic 'costs' to mothers. There were tendencies for female immatures to play with the mother more than male immatures did, and a tendency for the males to investigate the cage more than the females. Male and female immatures groomed non-mother group mates in equivalent amounts. Since males are likely the dispersing sex in galagos, these differences might be reflective of later dispersal patterns. However, comparisons are needed with a female dispersal species (e.g. chimpanzees) to test this hypothesis. Alternative hypotheses concerning the 'cost' and/or 'value' of sons versus daughters need to be explored.