Anne E. Russon is a professor in the Department of Psychology at York University in Toronto, Canada

Orangutans 101 I chose to study orangutans because most researchers in the field of great ape intelligence had ignored them, despite hints that beneath their sluggish exteriors they are exceptionally thoughtful. But if there wasn't much information on their intelligence, there was plenty on other facets of their adaptation; efforts to study wild orangutans began in the late 1950s. The job turns out to have its easy side. Orangutans spend their time slowly and serenely meandering through the treetops, just minding their own business. Unfortunately they do it in the almost inaccessible, swamp-logged, leech-laden tropical rainforests of Borneo and Sumatra. They also, on occasion, chase researchers out of their forests. It would take humans as obstinate as orangutans themselves to brave the discomfort of that environment to study them. Fortunately, there have been some. They now number in the dozens. The great red Buddha Orangutans signature feature has to be their red-orange color. Surprisingly, that is also one of the main reasons they are hard to study, because it makes them especially difficult to find. Finding a wild orangutan makes finding a needle in a haystack look like a kindergarten task in comparison. As a hint of how hard it can be, in the late 1950s George Schaller logged only 5.75 hours of direct observation of wild orangutans, after months of work. Part of the difficulty is that orangutans come quietly, in ones and twos, way up in the canopy, half hidden in foliage. On top of that, believe it or not, their orange color lets them vanish. Many researchers, myself now included, can attest to watching an orangutan disappear right before their eyes. The explanation lies in the way sunlight penetrates the forest. Because the rainforest is so deep and dense, most sunlight that filters through the canopy does so by bouncing off vegetation. Vegetation reflects green light -- the color we see -- but absorbs red and orange. By the time sunlight has bounced down through the canopy it has been robbed of its ability to register reds and oranges. In the midst of forest vegetation or on the forest floor, orangutans become large, dull brown lumps, just like the dead wood littered everywhere. Beyond color, orangutans' most prominent feature is size. Like all great apes, orangutans are exceedingly large -- in scientific terms, they come under the heading of megafauna. Largest by far are adult males, reaching 1.25 meters tall and over 100 kilograms in weight. Their strength is legendary, reputedly seven times as great as a man's. So much larger are adult males than other orangutans that the Iban Dayak people of north Borneo call them a separate species of orangutan, the biggest of three. The other two "species" are the middle-sized and the small (the Dayaks say they never get large). The middle-sized ones would be adult females and near-adult males and females, who are close to a meter tall and 35 to 50 kilograms, about half the adult male weight. Little ones would of course be youngsters. They weigh only 1.5 to 2 kilograms at birth and remain under about 25 kilograms for six or seven years. In this phase they grow so slowly, they could seem permanently small. Their growth spurts at adolescence, at least in males, but then they change so much as to be virtually unrecognizable. Adult males also differ from other orangutans in having cheek pads. a great drooping throat pouch, long, shaggy hair that can look like dreadlocks, and a distinctive "long call." Cheek pads are subcutaneous accumulations of fibrous tissue between eyes and ears that give their faces the look of giant pieplates or blinkered horses. Peter Rodman and John Mitani have suggested they may help aim the male's long call so that it travels farther, and their visual impact -- massive size -- makes a very convincing threat. These features are likely important to orangutans' mating system, in which adult males compete

Wealth of data... about the natural history, day-to-day behavior, and fate of these intelligent creatures.

A first-hand account of the lives of orangutans including a scientific history of orangutans, a description of orangutans and their natural habitat, their behavior patterns, rehabilitation operations, the politics of orangutan rescue work, and a look at orangutans released back into the forest.