“What a Nose!”

THAT reaction is common when people first see a male proboscis monkey with his pendulous, fleshy nose. * In some males, this appendage can grow to be almost seven inches (18 cm) long​—about one quarter the animal’s body length. Because the proboscis droops over the male’s mouth and chin, he has to push it aside when he eats! If your nose were similarly proportioned, it would hang almost halfway down your chest.

Of what benefit is this nose to the male proboscis monkey? * Theories vary. Perhaps his nose radiates excess body heat or adds resonance to his voice. Or it may serve as a visual warning to other males. Indeed, the dominant male’s nose swells and turns red when he becomes angry or gets excited. Another possibility is that the nose has a role in sexual attraction, setting the female heart aflutter! Most likely, though, the proboscis fulfills more than one function, perhaps including some we know little or nothing about.

Bulging Bellies

Proboscis monkeys​—male and female—​also have a distinct potbelly. In fact, their stomach contents may amount to a quarter of their body weight. As a result, both males and females tend to look permanently pregnant! Why the bulging belly?

The proboscis monkey’s stomach, like that of a cow, is filled with a soupy mixture of vegetation and bacteria. The bacteria ferment the food and break down cellulose, as well as  certain plant toxins that would kill other animals. Thanks to their amazing digestive system, proboscis monkeys are able to thrive on leaves and the nonsweet fruits and seeds of legumes, palms, and other plants​—foods on which primates with different stomachs could not survive.

The proboscis monkey’s strong digestive system, however, has a downside. The animal has to abstain from sugary fruits, which ferment rapidly. Such sweet fruits would make the monkey’s belly bloat, perhaps even to the point of causing a painful death.

Because of their cellulose-rich diet and complex stomach, proboscis monkeys need lots of time to digest their meals. So, after a hearty breakfast, they take a siesta​—sometimes for many hours—​before eating again.

A Social Animal

Whether eating or resting, proboscis monkeys are rarely alone. Dominant males preside over harems of up to eight females and their offspring. Males born into the group are evicted when they are old enough to care for themselves. These juveniles team up with other young males, forming groups that also have one or two larger males. To the untrained eye, such groups may appear to be a harem.

Proboscis monkeys have an unusual social trait​—harems often intermingle, especially in the evenings when they gather at rivers. At such times, a male will put on a show of strength if he feels that another male is taking an interest in his females. Usually the protective male​—who may weigh about 45 pounds (20 kg)—​will lean forward on all fours with his mouth wide open and stare at his rival. “If that does not have the desired effect,” says the book Proboscis Monkeys of Borneo, “the male then suddenly and unpredictably leaps through the trees, often with a loud roar, and frequently landing on dead branches which break with a sharp crack, adding to the general uproar.” Fights do occur, but they appear to be rare.

“Not only are proboscis monkeys unusual to look at; they also make the most bizarre range of noises,” says the book quoted above. The animals grunt, honk, roar, and squeal, especially in the evening, when they gather near rivers. In the midst of this cacophony, mothers may be quietly preoccupied with feeding and grooming their bluish-faced infants. Finally, by the time dusk envelops the forest, the animals will have found comfortable spots in trees​—usually tall trees by a river—​where they settle down to sleep.

Monkeys With Webbed Feet!

Besides their nose, proboscis monkeys have another oddity​—partially webbed feet. The webbing enables the animals not only to  swim well but also to walk safely on mangrove mud. Of course, thinking of tropical mangroves, you would likely also think of crocodiles. Crocodiles abound in the proboscis monkey’s domain. How do these aquatic monkeys avoid getting eaten?

One strategy they employ is to slip silently into a river and dog-paddle across single file, barely raising a ripple. When the river is narrow, however, they have been seen to use a different strategy. They climb high up in a tree, take a running leap from a branch, perhaps 30 feet (9 m) above the water, belly flop into the river, and then swim as fast as they can across the remaining stretch of water. Even mothers carrying infants use this tactic. Sometimes an entire troop will plunge into the water and make a mad dash for the other side! Their greatest enemy, however, is not the crocodile.

An Endangered Species

Officially listed as endangered, proboscis monkeys may number just a few thousand in their native habitat, and their numbers continue to decline​—largely because of humans. The man-made causes include fire, logging, unmanaged tourism, and the clearing of forests for oil-palm plantations. Another factor is hunting. Some people kill proboscis monkeys simply for sport. Others kill them for food or for use in traditional medicine. Because the animals often sleep conspicuously in trees next to rivers, they are especially vulnerable. Indeed, in one area frequented by hunters in speedboats, the number of monkeys fell by 50 percent in five years!

Conservationists are trying to raise awareness of the animals’ plight, and proboscis monkeys are protected by law in Borneo. But will these measures suffice? Time will tell. If this creature were to disappear from the wild, what a tragedy that would be, for the proboscis monkey is a study in oddities! What is more, the animal tends to fare badly in captivity.

The proboscis monkey is, of course, just one of many creatures whose future looks grim. Countless other species have already vanished. On the positive side, God has purposed to take full control of the earth, remove the wicked, and teach his people the right way to manage their terrestrial home. (Proverbs 2:21, 22) “They will not do any harm or cause any ruin in all my holy mountain,” Jehovah God promises, “because the earth will certainly be filled with the knowledge of Jehovah as the waters are covering the very sea.”​—Isaiah 11:9.


^ par. 2 The island of Borneo is home to the proboscis monkey. Local people call the animal orang belanda, or “Dutchman.”

^ par. 3 Females also have an enlarged nose, although it is not as big as that of the male.

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Proboscis monkeys have a distinct nose and potbelly

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© Peter Lilja/​age fotostock

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The male’s nose droops over his mouth. He has to push it aside when he eats

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© Juniors Bildarchiv/​Alamy

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Whether eating or resting, proboscis monkeys are rarely alone

[Credit Line]

© Peter Lilja/​age fotostock