WEAVING A TIGHT SOCIAL NET - ALLOGROOMING IN FREE-RANGING FEMALE LANGURS (PRESBYTIS-ENTELLUS)

We studied grooming among adults of a one-male multifemale troop of fr ee-ranging Hanuman langurs (Presbytis entellus) living near Jodhpur, I ndia, for 9 years. The 11-13 females devoted about 6% of their day to allogrooming. Adult males, whose tenures averaged 2.2 years, were tran sient figures in the troop's history, as reflected by their rather per ipheral role in the grooming network. Females groomed males 4-40 times more frequently (1006 episodes) than vice versa (176 episodes). Adult females received 97% of all grooming from other adult females (6655 e pisodes). Although females exhibited an age-inversed dominance hierarc hy, they did not compete for grooming access to particular troop mates . Dyads of all possible rank differences occurred as frequently as exp ected: 51% of grooming was directed up the hierarchy and 49% down it. Young, high-ranking individuals gave and received significantly more g rooming than the oldest, low-ranking females did The pattern seemed to be influenced by kin selection because of the presumably high degree of female relatedness. They invested most in troopmates with the highe st reproductive value, i.e., the youngest individuals. This trend was coupled with a preference of closest kin (mothers and daughters). Reci procity was the outstanding feature since all adult females groomed an d were groomed by all others. Such a tight social net might establish the necessary cohesion during frequent territorial disputes with neigh boring troops.