Abstract # 91:

Scheduled for Thursday, August 18, 2005 07:00 PM-09:00 PM: (Cambridge/Oxford Room) Poster Presentation

Sex Differences in Juvenile Phayre's Leaf Monkeys (Trachypithecus phayrei)

K. Ossi1 and A. Koenig2
1Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794-4364, USA, 2Department of Anthropology, Stony Brook University
     The long immature period in primates provides time to develop physical and social skills for adulthood. Past research focusing on female-philopatric taxa suggests that already as juveniles, females are more central and affiliative and males more peripheralized and less social. In this pilot study we compare juvenile females and males of Phayre’s leaf monkeys (Trachypithecus phayrei). Because females and most likely males disperse, we expected weak sex differences. Data were collected on 2 study groups consisting of 9 juveniles (4 females, 5 males) at Phu Khieo Wildlife Sanctuary, Northeastern Thailand. Affiliative and agonistic interactions were recorded using instantaneous and continuous focal sampling. Data on juveniles’ neighbors and spatial positions within the group spread were collected at the start and end of 20-minute protocols (67 hours of focal data). We compared proportions of time spent in different activities and investigated partner preferences by age-sex classes using Mann-Whitney U-tests (α < .05). Results suggested no significant differences in the proportions of time that immature males and females spent in affiliative behaviors or in the age-sex classes of social partners, but males tended to be more often alone than females (not significant). The distance to the group center did not differ among the sexes. Although these are preliminary results based on small samples, the general lack of strong differences between juvenile females and males supports the idea that dispersal patterns exert influence on behavioral sex differences during juvenile development. Supported by ASP General Small Grant.