Species Spotlight: Gibbons

Picture a tree. This tree is roughly 40 meters tall. It sticks above the forest canopy by a good 15 meters . Now put yourself in the top of that tree. It is breezy up here -- unlike the steaming forest floor below where the sun tries to evaporate a month of rain in one clear day. This is your tree. From here you can see your entire territory. Picture the view: to the south, mountains; to the east, a river; to the north forest; and to the west... well, let's not talk about that yet.

Now while you are sitting in the top of this tree, feel your legs shorten to half their length while your arms stretch by a similar amount. Flex your wiry arms as  you watch them sprout thick black fur. Go ahead and keep sprouting fur over your entire body, but, just for grins make your eyebrows and beard white (yes, even you ladies). Do you look a bit like a Muppet? Good, because the fun is about to begin - and you might as well look good doing it.

Let's start with a warm-up.

Clear your throat quietly, take a deep breath, then let out a high-pitched ascending "Whoop!" followed by a brief pause, then another. As you loosen up, try a series of 3 whoops in a row. At this point, you can continue whooping, creating a hauntingly shrill song that echoes among the treetops, or you can fall off the branch you are sitting on.

Seriously, just tip over and fall off the branch, riding a few seconds of gravity through the canopy before you deftly extend your impossibly long arm, catch another branch in your hook-like hand, and swing around, underneath, and slingshot yourself back on an upward trajectory, your other hand outstretched for the next branch. This method of travel, called brachiating, allows you to fly through the tree-tops with the greatest of ease -- crossing distances of 15 meters or more and reaching speeds of 35 miles per hour. It is as if the laws of physics were created to propel you. Congratulations. You are a gibbon: natures take on what would happen if Maria Callas and Jules Leotard had a love-child created by Jim Henson.

Despite their agility, good looks, and great voice, these lesser apes tend to be overshadowed by the poster-child for Indonesian rain forests: the shaggy Orangutan. Which is unfortunate, because in many ways Gibbons share more in common with us than other non-human primates:

  • They are the only other primates that walk bi-pedally -- often strolling across the tops of branches like a tight-rope walker, their arms raised above their heads for balance.
  • Like many humans, Gibbons are monogamous, but, like many humans not necessarily for life, practicing what is known as "serial monogamy," or having multiple successive partners for a period of several years. This monogamy is possibly "aided" by the female's potentially vicious tendency to "defend" their males from other females (again just like many humans.)
  • They are territorial, and although they don't nest like most of the Great Apes, they will often return to the same tree to sleep at night and patrol their territory during the day looking for trespassers.
  • They love (and here is where the similarity breaks down for some of us) to sing in the morning, performing sunrise duets with their mate and offspring.

The song of the gibbon is one of the most recognizable sounds of Gunung Palung National Park.

The series of ascending and descending whoops, calls, hollers, and cries last for several minutes, echoing nearly two miles through the thick canopy. Often sung in duet, the female will take the lead with the male chiming in his accompaniment. The songs are thought to identify the extent of a families territory, as well as to warn off home-wrecking females (see point 2 above). However, the song of the gibbon is slowly being replaced by the song of the chainsaw.

There are 16 species of Gibbon (this number varies depending on how you divide them) found throughout Southeast Asia, ranging from southern China to Borneo, East India to Vietnam. Of those listed by the International Union for Conservation of Nature and Natural Resources (IUCN), 15 are considered "endangered" or "critically endangered," and only one species' population is stable -- the rest are decreasing.

Habitat loss threatens gibbons on a daily basis. As forests are cut for timber or cleared for agriculture and oil palm plantations, the gibbons are forced to try and survive in fragmented forests or in the upper reaches of the mountains. There, food is scarce and populations decline. Those that live on the edge of the forest run the risk of being shot by hunters for bush-meat, or captured for the pet trade.

Picture your tree. To the west, the next tallest tree, only a kilometer away, shakes awkwardly for a moment before slowly toppling to its side. You watch it silently disappear into the forest before the roar of breaking branches reaches your ears. Picture yourself listening to the sound of chain saws as you sit in the crook of the branch, your infant clinging to your fur as the rain begins again.

Loren Bell spent three years chasing gibbons while managing the Gunung Palung Gibbon and Leaf Monkey Project. This long-term research project studies how habitat quality and ecological factors affect the demographics, behavior and reproductive potential of several primate species found in Gunung Palung National Park.


About LBell | View all posts by LBell

Loren is the IT Manager at Health In Harmony, based in Taos, NM.