The Hair-Raising Jungle Chorus

By “Awake!” correspondent in Suriname

IT BEGAN as an eerie sound: “Rohooo, rohooo, rohooo.” Then more voices joined in a moaning that built up to a long, vibrating crescendo like the roar of a gale blowing through a tunnel. The cries waned for a moment, only to burst out with renewed force. Finally the voices fell silent, and the echoes died away. Gradually the buzzing of insects and the chirping of birds filled the jungle air again.

I listened in amazement while sizing up the performers of this hair-raising jungle chorus: five sturdily built baboens,a as the red howler monkeys are called here in Suriname.

“Here in Suriname,” a biologist told me, “you find them from the swampy coastal areas in the north to the dense jungle in the south. They live high up in the trees, especially in the forests along the rivers, in groups of four to eight and sometimes more.”

As I watched, the star performer, an old male standing almost three feet (0.9 m) tall, bigger and heavier than the other four, came closer and growled. His head, half of it consisting of a huge lower jaw, sat deep between his shoulders, giving him a hunched appearance.

The naked face contrasted with his orange-red body hair. And a distinct yellowish-orange beard proclaimed his dignity and covered the source of all those spine-tingling roars​—his swollen throat. Why is it swollen? The Jivaro Indians have an amusing answer:

‘One day,’ goes the story, ‘the howler showed the spider monkey how to break coconuts by pounding them together. When the spider monkey tried it, his thumbs got caught between the nuts and were lopped off. Determined to revenge his loss, he told the howler, “Don’t crack them at all. They taste much better when swallowed whole.” The howler followed his advice, but the coconut got stuck in his throat and left its mark on all his offspring, while the offspring of the spider monkey went without their thumbs.’

But when the Jivaro Indians shot a howler and looked inside its throat, there was no coconut. What did they see? A cup-shaped, hollow sound box of enlarged bones in the swollen throat. This built-in echo chamber, the size of a lemon, is 25 times bigger in the male baboen than the same body part in other similar-size monkeys, and it is unique among mammals. As he contracts the muscles of his chest and stomach, air is forced across an opening in this hollow sound box, and his voice is amplified so much that it can be heard over two miles (3.2 km) away.

Observers have found that on moonlit nights the howlers get “talkative” and do not mind skipping their night’s rest and disturbing yours. But don’t think they will sleep in the next morning. Just before sunrise they are up for a howling, and at the end of the day the chorus lines up again for their embarrassingly off-key serenade.

Wildlife author Richard Perry adds that “a clap of thunder or sudden downpour, a passing aeroplane or even a flight of butterflies” will get them howling. You wonder: Do they ever take a break?

“They do,” a former zoo director told me. “The two howlers in my collection loved to take sunbaths. They selected a barren branch, wrapped their tail around it, and stretched out belly down. With long arms and legs dangling loose, they dozed off.”

But even sunbathing whips up an appetite. The old male decides it’s time to eat. He makes a gobbling sound, and the others get up and follow him to another tree. All have a set place in the train​—the leader up front and another male at the end. Secured in between are the females. Playful youngsters sometimes break ranks, but a reproving growl is enough to bring them back on the right path. And that path is always the same. One researcher wrote that they have their own traffic roads and follow a fixed route across the same horizontal branches.

While feeding, they use their handy tail. Hanging by it with head down, they swing with arms and legs free, grabbing fruits, flowers, and seeds. However, many kinds of leaves​—and lots of them—​form their staple diet. But vegetarians, beware! Don’t order from their menu!

An experienced naturalist told me: “Whenever you’re lost in the jungle, you can survive by eating what the monkeys eat.” However, the natives warn: “Whatever the spider monkey eats, humans can also eat, but not what the baboen eats. That’s because the howler eats poisonous plants. So after a time their teeth get a brown color, like that of a chain smoker.”

White or brown, all teeth are shown when other monkeys come too close to the group. They love their privacy to the point of being unsociable. But other monkeys don’t care much for them either! When one animal collector felt pity for a lonely baby howler, she wanted to cheer him up by giving him a gentle female monkey as a companion. But the female “took one look at the ugly howler and started screaming as if she’d seen a bogeyman!”

William, a veteran hunter from Guyana, once spotted a howler with a stranger​—the spider monkey. The two were standing on a branch facing each other. But it was cutthroat business. Recalls William: “Their tails were coiled around the branch for support, and their free arms were slashing out, grabbing at each other. They were screaming and biting, but the howler had the upper hand.” Were they still arguing about that coconut?

Even other red-howler groups are told, ‘Mind your own business.’ When one group of baboens dares to invade another’s territory, a vocal battle explodes that lasts until one group retreats. Conclude most researchers: “Keep your distance!” is the main message of the jungle chorus.

The “Parson” in Charge

The howling may sound like bedlam to us, but actually it has arrangement. “The domri [parson] is the chorus leader,” said Raymond, a gold-seeker who observed howlers around his bush camp.

“Domri?” I asked.

“Yes, so we call the old male. In the church here it’s the custom that the domri sings the first verse of a hymn, and then the other church members join him. The baboens do the same.”

Raymond further explains that before the chorus begins, the leader walks up and down and looks gloomily at the members of the group, like a stern conductor inspecting his orchestra. When satisfied, he starts warming up with a series of chesty roars. Then the others add their howling, their lips shaped into a funnel as they gravely look at each other. “It’s really funny,” says Raymond, “those glum faces. All work and no play.”

Their Enemies

There are moments, though, when even the conductor forgets about order. When jaguars or harpy eagles attack, there is utter confusion, with all chorus members jumping helter-skelter for their lives and even swimming across a river to get away.

However, the howlers’ most dangerous enemy is man. Although the howlers are protected by law, they are hunted for their meat. ‘In one Amerindian village with a population of 450 persons, 56 howlers were shot and eaten in one month,’ revealed one study. No wonder that in some areas their numbers are decreasing. And those that survive retreat deeper into the jungle.

But whenever their chorus swells from faraway hiding places, they remind us that they are still there​—broadcasting their cry: ‘We are here. Keep your distance!’

Will man get the message?

[Footnotes]

[Blurb on page 23]

His voice is amplified so much that it can be heard over two miles away

[Picture Credit Line on page 21]

cZoological Society of San Diego

[Picture Credit Line on page 22]

cZoological Society of San Diego