PRELIMINARY EVIDENCE FOR THE HIRED GUNS HYPOTHESIS AND INDIRECT MATE DEFENCE IN A WILD GROUP OF MAROON LANGURS Presbytis rubicunda (Müller, 1838) IN SABANGAU TROPICAL PEAT-SWAMP FOREST, CENTRAL KALIMANTAN, INDONESIAN BORNEO.

Group-living primates enjoy numerous benefits, including effective resource defence from conspecifics in other groups. Resource contest often results in intergroup aggression, for which several hypotheses exist to explain its function: direct mate defence; direct food-resource defence; indirect food defence via 'hired guns'; mate attraction via infanticide, and indirect mate defence via male resource defence. I studied a focal group of Maroon Langurs Presbytis rubicunda in Sabangau tropical peatswamp forest and examined the nature of intergroup aggression. Evidence supported direct mate defence in the majority of intergroup encounters. However, given that the resources in this frugivorous population may be defensible, and that most intergroup encounters occurred within their 'core range' of valuable resources, it is likely that the females in the group benefited from indirect resource defence as a result of aggression by the male as a 'hired gun'. The focal group was the subject of a takeover by an invading male. The post-takeover home range and core range overlapped pre-takeover ranges by 75% and 43% respectively and post-takeover, the group reused 47% of sleeping trees (N=14), suggesting that the invading male established himself in the territory of the resident females, who then continued to use the resources therein. The focal group also fulfilled three criteria proposed to predict indirect mate defence via male resource defence in colobine monkeys. Thus, it appears that indirect mate defence may have been employed by the invading male to obtain reproductive access to females. This study represents the first preliminary evidence for both indirect-resource-defence-via-hired-guns and indirect-mate-defence-via-resource-defence hypotheses in the genus Presbytis. [ABSTRACT FROM AUTHOR]