There are currently only about 5000 Sumatran orangutans left in the wild and Bukit Lawang is one of the few places you can see them in their natural setting. In doing so you can help protect them - a few tourist dollars into the local economy provides an added incentive to preserve both orangs and their habitat - and that habitat is facing critical threats.
Throughout their range forest is being cleared for oil palm and rubber plantations. This is widely documented and probably the major threat to the survival of this species and many others. But all is not well at the local level either, and visitors can really help orangutans by insisting on a responsible approach to local tourism.
Too many of the guides are not well trained, and some commit the serious error of offering food to orangutans encountered when on forest treks. This is both irresponsible and dangerous, setting back the rehabilitant orangutans who are learning to become less dependent on human care, and increasing the risk of disease transfer. It doesn’t help the tourists either – one 30 odd year old female orang (“Meena”) has become aggressive and can be a risk to visitors. It is very tempting to touch the orangutans, but you would only be adding to the problem.
Take advice from the Park authorities and people like Samsul (of "Sam's Bungalows"), to recommend good and responsible guides who know and respect the forest and do not put the orangutans in danger. Then you can relax, learn about the forest and leave only the imprints of your boots in the soft forest floor.