HARVARD GAZETTE ARCHIVES

National Geographic researcher Cheryl Knott of Harvard University collects orangutan urine as part of an ongoing study of the animals' physiology and behavior; she has learned that female orangutans only conceive during periods of high forest fruit production and nutritional intake. (Photo by Tim Laman/National Geographic)

But she's also seen the inroads that illegal logging has made in the Gunung Palung National Park where her studies are based. She knows the apes, which live almost entirely in the forest canopy, cannot survive without the trees. And she knows that the vanishing trees at Gunung Palung make up one of the last orangutan strongholds on the planet.

"There's just been an amazing degradation of the forest in many of the areas surrounding our study site," Knott said.

When she arrived at the Cabang Panti Research Camp in 1992, Knott found pristine forest, reachable only by dugout canoe. Soon, however, she could hear the distant sound of chainsaws. Today, she can walk to the camp on foot, through paths and roadways cut by loggers. Peat swamp forests that used to support towering trees now support rice paddies to feed local people.

A widely cited estimate is that at current rates of deforestation, orangutans will be extinct in the wild in 20 years. But Knott, who heads the Gunung Palung Orangutan Project, believes all is not lost. Despite the increased logging, Gunung Palung still supports a healthy orangutan population, estimated to be about 2,500, perhaps one-tenth of those remaining in the wild. Knott says there are healthy populations at perhaps six to 10 other locations. If they can be protected, Knott said, the species can be saved.

"There are just a handful of viable populations in the world; one is at Gunung Palung. If we protect those, there's hope," Knott said.

For the past decade, Cheryl Knott has helped humans understand orangutans. With the lowest mammalian reproduction rate in the world, orangutans have very little capacity to recover from local population crashes or from major habitat disturbances. (Staff photo Rose Lincoln/Harvard News Office)

Low reproduction rates

For the past decade, Knott has helped humans understand orangutans, their treetop world, and their precarious grip on existence. With the lowest mammalian reproduction rate in the world, orangutans have very little capacity to recover from local population crashes or from major habitat disturbances.

Orangutans breed an average of once every eight years, and produce just one young per breeding. While that is extremely low compared with other mammals, Knott has found that to be in tune with the orangutans' environment.

Though the rainforest may look lush, the fruit that orangutans prefer to live on can be quite rare. The tall rainforest trees tend to produce fruit all at once, during an event called "mast" fruiting. Scientists think the rainforest trees adopted this strategy as a way to overwhelm insect pests, ensuring that some fruits get the chance to grow into new trees.

The problem, if you're an orangutan, is that these mast fruiting episodes average just once every four years, and can range as long as 10 years, though there are smaller annual fruiting peaks.

In the meantime, orangutans have learned to survive by eating lower-quality foods, such as leaves and bark. These foods provide enough sustenance for the apes to survive, but Knott has shown that their daily energy intake falls to less than 2,000 calories, compared with as high as 10,000 calories during fruiting periods.

Knott's work has shown that the orangutans' reproductive cycles are keyed to these periods of high fruit production.

By spreading plastic sheets under the trees where orangutans reside, researchers have collected samples of urine, which they've tested to determine hormone levels. Knott said hormones are higher during periods of high fruit availability. On the other hand, ketone levels, which indicate the ape is burning fat, are elevated during low fruit availability.

Knott said the picture that has emerged is that orangutans conceive their young during periods of plentiful food, which will provide them with the extra energy needed for gestation, lactation, and parenting. That makes sense, Knott said, because they can't predict food availability in the future, but they can time reproduction for when they're in the best physical condition.

Knott's more recent work, detailed in National Geographic, has focused on the two different types of reproductively mature males. One type of male is much larger than the others, much more aggressive, and is marked by large cheek pads not present in females. The second type of male is smaller, nonaggressive toward other males, more commonly engages in forced copulation, and does not have cheek pads. Males of the second type usually develop into the first type, called "prime" males, but the timing of this development is very variable and the phenomenon is poorly understood.

Knott has discovered that the males in their prime usually don't stay in that prime form very long. After a few years they become what she terms "past prime males" who rarely mate, have shriveled cheek pads, do not produce the characteristic male long call, and are nonaggressive. This is not seen in zoos where males can maintain their prime form indefinitely. Her theory is that being a prime male is so difficult - they are larger, fight other males more, and follow females around more waiting for an opportunity to mate - that an individual male can only sustain that form for a few years. Thus, she suspects, the timing of male development is critical, leading to a variable development period.

As with female reproduction, Knott suspects that the prime form is linked to food availability and that males time their passage into this phase of their lives to coincide with periods of greater food availability and greater female receptivity. The number of other prime males in the area may be a factor as well, she said.

Preservation through education

Hand in hand with the scientific work, Knott and her team are trying to save Gunung Palung through education. Though logging in the park is illegal, and police have responded to researchers' reports of illegal activities, loggers invariably return shortly after the police leave.

The multipronged education effort, begun in 1998, is attempting to raise environmental awareness in the surrounding communities in hopes a budding environmental consciousness will lead to locally grown efforts to preserve Gunung Palung and to stop illegal logging.

The work entails bringing students into the research station and letting them observe orangutans, doing outreach to the local schools through in-class lectures and teacher training, and creating an environmental curriculum as a resource for teachers.

Knott said this outreach is essential if there are to be orangutans to study in the future. Researchers are there for a year, or a season, but the local people live in and around the park year in and year out. Despite that proximity, many of the children in the surrounding towns have never seen an orangutan, either live or in a picture.

Since its inception, the program has reached 5,000 children and several hundred teachers. She said the children who visit the research site, mostly high school kids, are energized and excited by the experience. One result, she said, is that nature-lover clubs have sprouted in several local schools.

In addition to efforts targeted at schools, the project also has a regular radio show; has sponsored billboards and coloring contests; supported local park rangers; and meets regularly with government officials on the subject.

"I feel like if we hadn't been doing this the last few years, we wouldn't have a site anymore," Knott said.