In Tanjung Puting National Park, long-tailed macaques (Macaca fascicularis) are a fairly common sight along the Sekoyner River. During the late afternoon they can often be seen preparing to roost in the tall trees along the river’s banks. Amongst these riverside monkeys, dwells one group of long-tails that lives around the Rimba Orangutan Ecolodge. These high-profile monkeys have become the center of attention for the Rimba Macaque Project. Having first begun in 1999, the project is aimed to become an ongoing study to monitor the social behavior and habits of the Rimba’s long-tailed gray monkeys.
Long-tailed macaques are well-known for their fondness of human settlements and are the same species of monkey that are found in the Hindu temples of Bali and Lombok. Although historically these primates have mainly lived in primary riverine or swamp forests, they have learned to acclimate quickly to disturbed secondary habitat and human settlements. In many situations, they seem to now prefer the latter habitat types, as these smart and adaptable monkeys are attracted to the greater abundance and easier access of food sources. This is why the macaques are seen so frequently around the Rimba Lodge – they are looking for leftovers from the people.
Because of their close association with people at the Rimba Lodge, the Rimba macaques present a great opportunity for studying detailed social interactions because it is not too hard to get up close and personal with them. This may sound easy compared to tracking wild orangutans for miles in the forest, but working closely with a wild primate that accustoms to humans so easily presents its own unique problems. Macaques are known as ruffians in the primate family, and if you get too close during the wrong situation you could end up with the biggest scare of your life – or even the biggest scar of your life. Additionally, recording everything that goes on in a monkey’s high-paced social world is incredibly hard to keep up with, even when they are in plain view – which often times they are not.
The main focus of the Rimba Macaque Project thus far has been on three basic issues. First, the basic premise of Robert Trivers’ (1971) theory of reciprocal altruism is being tested by exploring patterns and sequences of social behavior exchange. The idea is that if reciprocity has an influence on exchanges of social favors then patterns of trading social acts should be observable. Furthermore, the theory of biological markets is also being tested by exploring the influences that availability and abundance of social partners can have on grooming exchanges. For example, does the abundance of available females influence how long a male will groom a female before mating, or does the abundance of available infants influence how long a female will groom a mother before handling her infant?
Finally, genetic samples are being collected from hair, urine, and fecal specimens. It is hoped that later on we will gain permission from the Indonesian government to export these samples and conduct two basic analyses. First, kin networks and offspring sired will be verified using techniques to amplify microsatellite regions of the genome. These highly repetitive regions of DNA can be matched for similarity amongst individuals and can be used as a crude measure of relatedness or to exclude potential sires of offspring. Secondly, regions of the major histocompatibility complex (MHC) will be amplified to test if partner preferences for mating can be predicted based on differences at these loci. The theory is based on the MHC regions role in an organism’s immune system. Evidence in other mammals has shown that individuals more frequently select mates whose MHC genotype will allow their offspring to develop stronger immune systems. Researchers are now seeking to find out if this occurs in primates as well.
Data was collected daily at and around the premises of the Rimba Orangutan Ecolodge by me between July 03′ and August 04′. The work is continuing at present and the project’s tasks are now being carried out by my research assistant, Peltanadanson, while I complete my dissertation at the University of Georgia in Athens. The project will continue indefinitely into the future as long as it continues to have the much needed support from the Rimba Orangutan Ecolodge and other funding sources. Overtime, it is hoped that enough support will be obtained so that the project can mature into a long-term research project that will incorporate a much broader range of research topics.
In 1999, the project was supported by John E. Schaible III, the Orangutan Foundation International, and from personal funds. A Fulbright Graduate Fellowship was awarded to continue the project during 2003-2004.