IMMATURE MALE AND ADULT MALE INTERACTIONS IN BISEXUAL LANGUR (PRESBYTIS-ENTELLUS) TROOPS

One bisexual troop of langurs (P. entellus) was investigated for 32 mo. at the Junbesi-Ringmo study site in Nepal. Observations occurred during 3 separate studies and span a period of 6 yr. All members of the study troop were individually recognized throughout the 3 studies. Data were collected on immature male (from birth to 5 yr of age) social relations with adult males. Social relations between these 2 classes of males varied both in type and in frequency of behaviors displayed. During the 1st study, when the troop was predominantly multi-male, young males directed various tense behaviors toward adult males. Monthly rates of occurrence of such behaviors fluctuated and showed a positive correlation with rates of agonistic behaviors between adult males. In contrast, interactions between the adult and immature males were considerably more relaxed during the 2nd and 3rd studies when the troop had but 1 adult male. It is hypothesized that the frequency and patterning of interactions between adult males affect adult male relations with young males.