1Anthropology, University of Wisconsin-Oshkosh, 2Anthropology and Biological Sciences, University of Southern California
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Red langurs (Presbytis rubicunda) are endemic to the island of Borneo and are distributed widely throughout the island. However, aside from a few short-term studies, little has been reported about the behavioral ecology of this species. Although variable patterns of ranging and possible fission-fusion sociality were suggested by previous studies this has not been confirmed through further research. Here we report preliminary data on the ranging patterns of red langurs from a newly established field site in the Wehea Protected Forest in East Kalimantan, Indonesia (01°32’46”N, 116°46’43”E). Data were collected from a single habituated group consisting of 11 individuals (1 adult male, 3 adult females, 1 subabdult male, 3 subadult females, and 3 juvenile males). Data were collected through follows each month between January-July 2011 (n=650 hours). GPS coordinates and group scan data collected every 15 minutes were used to assess ranging patterns and group cohesion and spread. We found that the study group had a home range of ~72 ha that appeared to overlap considerably with the home ranges of at least two other groups of red langurs. We observed 11 occurrences in which the study group split into two distinct subgroups separated by >300m that traveled and foraged independently for at least 1 hour, and on at least two occasions slept in separate locations. These fission events and the generally low levels of group cohesion observed may be a response to resource competition and overall low availability of resources in Borneo generally and East Kalimantan in particular.
This research was supported by Primate Conservation, Inc., the University of Wisconsin-Oshkosh, and the Univeristy of Southern California.