km2), and the orangutans here are found in social groups more often than anywhere else they have been studied. In addition, the site is home to four species of monkey (Macaca fascicularis, M. nemestrina, Presbytis thomasii and P. cristatus), two species of gibbon (Hylobates lar and H. syndactylus), plus tigers (Panthera tigris sumatrae), bears (Helarctos malayanus), wild pigs (Sus sp.) and a remarkable diversity of other wildlife.

Yesterday, chainsaws were felling trees within only about 25 meters of the dock, along the river at the base of camp. From the main camp building, we could see some of the trees falling and heard trees crashing down at a rate of one every three to four minutes. The area where the loggers were working had been an active phenology plot, where the growth and productivity of various species of trees that produce food for orangutans were being tracked. It is estimated that all of the trees over about 20cm in diameter were being removed.

The logging is definitely having an impact on the behavior of the wildlife in the area. Though encounter rates have not been systematically recorded, the impression of many of the researchers and assistants is that the frequency of encounters with orangutans and tigers inside the research area has increased in the last two months, probably due to a loss of other suitable habitat in the surroundings. The noise and disruption from the logging also has a direct effect on the behavior of some animals. While logging was going on along the river near camp, many hornbill birds were disturbed, fluttering around and squawking in distress. The sound of crashing trees evoked a long-call response from an adult male orangutan.

The station manager, the Leuser Management Unit, and foreign researchers have asked the government for assistance from the police or military in stopping the illegal logging and protecting the safety of those working at the research site, but no help has been forthcoming in recent months. The loggers are making no effort to hide their illegal activities within the park, because they believe the regulations will not be enforced. Just yesterday as I was leaving the station, a logging truck filled with timber was blocking the road leading out of the park, well within the national park boundaries and in the middle of the day.

The current logging is also making further research nearly impossible. Several research assistants have been threatened, told that if they were to interfere with the logging, the chainsaws would be used on them. These research assistants are people who were hired for their skill at taking data. They are not armed beyond a small knife to help them keep the trails clear, and are not trained or expected to provide defense. They have avoided confronting the loggers, and though most encounters with loggers and poachers have been quiet and peaceful, a few have ended in threats of violence from the encroaching parties. Even in the center of the research area, where no logging has been seen yet, loggers and poachers are being encountered more often, and the student researchers and research assistants fear for their safety.

Suaq Balimbing is one of the world's most important research sites for primate behavior, as it is the only site where orangutans are known to regularly make and use tools to get food. The orangutans at Suaq use tools to get honey and insects from holes in trees, and to get the rich seeds from a fruit with a tough husk and stinging hairs. Though the use of tools by wild chimpanzees has been well-documented, we have just begun to investigate orangutan tool use and its implications for understanding the origins of human material culture. The high level of sociality seen among the orangutans at Suaq may be directly related to their use of tools.

Is the flowering of sociality and hence culture we see in the orangutans at Suaq a reflection of past glory or the opening of a new path? This depends on whether we think the habitat, and subsequent population density, we find at Suaq is typical of what most orangutan habitat was like before widespread habitat modification by humans.

If such swamp forests were more common thousands of years in the past, then we might expect that the population density and behavior of the orangutans at Suaq is "normal" and "natural" -- in fact, these might be the circumstances under which the orangutan's tremendous capacity for social learning evolved. This would mean that Suaq Balimbing is one of the last remaining "normal" orangutan habitats, and everywhere else we currently find orangutans is marginal habitat where their behavioral repertoire has been limited.

On the other hand, if the high population density at Suaq is a result of an "unnatural" squeezing due to pressures of habitat loss elsewhere, we might be witnessing the first steps of a key evolutionary change: the transformation of intelligent extractive foragers into cultural beings.

Either way, the incredible significance of this site and the population of orangutans who inhabit it cannot be overstated. They must be saved!

Taking action in defense of the forest in and around the Suaq Balimbing research situation is vitally important, and it must be done quickly if there is to be anything left. Please give any assistance you can to help preserve this amazing and threatened resource.

Sincerely,

Michelle Y. Merrill
Ph.D. Student
Department of Biological Anthropology and Anatomy
Duke University

* The original posting contained some errors. The affected area (144 hectares) and some taxonomic errors and misspellings (Macaca nemestrina, Presbytis cristatus, Hylobates syndactylus, Helarctos malayanus, Sus sp.) have been corrected.

The addresses for writing letters (also updated) are now available here.

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