From her favorite spot up in the climbing structure, Indah the orangutan has a sweeping view of her habitat. Janey is sprawled on the grass, the morning rays filtering through her red hair to warm her skin, while Karen somersaults her way to a spot at the large exhibit window, where she can do some people watching. Satu slowly knucklewalks from one side of the habitat to the other, dragging a large piece of burlap clenched in his right foot. Once he reaches the perfect spot, he hunkers down, methodically drapes the cloth over his head, and begins plucking leaves from a branch of browse. The two lithe, black-haired siamangs that share the exhibit with the red apes sit together on a large boulder, one grooming the other. It's another beautiful morning at the San Diego Zoo's ape habitat on Orangutan Trail.
Our orangutan group has been through some changes during the past two years. Not long ago, keepers rotated two groups of orangutans: Clyde, a male, along with females Karen and Janey, and younger male Satu with female Indah and their son, Cinta. When a zoo in Kansas needed an experienced mate for their female, Clyde moved there to take on the role.
As a result of the move, the keepers were able to put all of our orangutans together again. In the wild, orangutans are actually mostly solitary. Many may feed in the same area in their natural habitat, but there is not much interaction between individuals, except, of course, between mother and offspring and male-female courtship. Yet putting all of our orangutans out together each day works quite well. "We're seeing a cohesive group of happy apes," said Tanya Howard, senior keeper. "But the most exciting thing happening is the physical change in Satu. It's something we had heard about but never experienced."
Broad cheek pads, called flanges, long "dreadlocks," and greater body size are characteristics of a dominant male orangutan—but only the dominant male. Other males that live and feed in the same area don't develop these secondary traits, a phenomenon called suppression. But once a suppressed male gains a territory of his own, his flanges, hair, and body grow.
Life without flanges isn’t so bad; suppressed males are able to be where the food is without constant dominance battles. And while he may not look big and impressive, an unflanged male can—and will, given a chance—mate with as many females as possible. Females tend to choose flanged mates, but there’s always a chance a nondominant male can catch a break.
Since Satu grew up in the presence of his father, Clyde, keepers and Zoo members witnessed this occurrence firsthand. By the time Satu was 15 years old, his growth had slowed and he had no flanges—yet he still caught Indah's eye. Apparently, Indah didn’t get the memo about females preferring flanged males. Clyde often tried to mate with her, but she avoided him, choosing instead to solicit attention from Satu. Indah gave birth to Satu's son, Cinta, in 2004. At that time, all the orangutans lived together. However, when keepers noticed Satu beginning to act fearful of Clyde and making a great effort to stay far away from the huge guy, they created two separate groups. Still, Satu's face remained flangeless.
With Clyde's move to Kansas in 2011, his inhibiting effect went with him, and Satu began to transform. He bulked up. His hair became longer and coarser, and his face flushed with the beginnings of flanges. Satu wasn't the only one in which keepers noted a change. "When Clyde was here, Indah would stay in one or two areas of the yard, even though she wasn't out at the same time as Clyde," said Kim Livingstone, lead keeper. "Since Clyde’s departure, she's been using all areas of the exhibit."
Putting all the orangutans together has added a little spice to Satu's life in other ways. Although he had not been grouped with Karen for a few years, Satu took an instant liking to her. Janey and Indah, on the other hand, didn't seem to care about Karen's presence, which was expected. "The females generally tend to ignore each other, as they would in the wild," explained Tanya. "Well, except for Karen. She'll go right up to the other females and try to start grooming them. They scoot away at first, but if she’s really persistent, they'll give in."
From their up-close presence at the large exhibit windows (where you might wonder: who is watching whom?) to their agile movements through the maze of ropes and poles on the climbing structures, the Zoo's orangutans are crowd pleasers. In their native habitat, orangutans spend more than 95 percent of their time in trees. And as Tanya points out, "We have a very outgoing, arboreal group."
The spacious yard, active apes, and red-shirted volunteer with props and information give visitors a chance to begin to understand how important large areas of forest are to the survival of orangutans. Unfortunately, this type of habitat in Southeast Asia has been clear-cut and burned for agricultural purposes such as palm oil plantations. "There are only 6,000 to 8,000 Sumatran orangutans left in the world," said Tanya. "There are generally more people at the Zoo on any given day than there are Sumatran orangutans in the wild." With our engaging orangutans serving as ambassadors for their kind, that’s something that can change, too.