ECOLOGY OF FEMALE SOCIAL RELATIONSHIPS - HANUMAN LANGURS (PRESBYTIS-ENTELLUS) AND THE VAN SCHAIK MODEL

The ecological model of Carel van Schaik provides clear predictions fo r female-female relationships in relation to scramble or contest withi n-group competition and contest between-group competition. These predi ctions were applied to data from a 12-year field study on Hanuman lang urs (Presbytis entellus) that ranged freely around Jodhpur (India). It appears that hierarchical relationships between females (unstable, in consistent, individualistic, with low rates of agonistic coalitions) r eflect scramble within-group competition. Such competition, however, r esults in individual evolutionary advantages (differential feeding tim e; differential reproductive success) so that dominance effects mirror contest within-group competition. Between-group contest competition a t Jodhpur is strong (low predator pressure, high population density, g ood food defensibility, essential role of females during intergroup en counters, loud vocalization of males). The results are discussed in th e light of langur feeding habits.