The world’s loudest-mouthed bluffers and braggarts are these dwellers in the high treetops. They swear in an ancient tongue evolved over centuries for the effective cursing of hovering white hawks, black vultures and lurking wild cats. Now they curse, loudly and most profanely, airplanes which sweep low over Panama and Costa Rican jungles. They have not found it necessary to invent any new expressions to convey their contempt for the new monsters of the skies.
Their voices are their only weapons. These have proved quite effective throughout the lifetime of the race. The howlers have been able to threaten their enemies with perdition so convincingly that these enemies have believed the threats. Largely as a result, the big black monkeys have been left alone as the dominant animals of the weird, perilous green world at the top of the jungle. They never have had to fight with fists, claws or teeth. All they have done—all it has been necessary to do—is talk about it.
The scream of the howler, hurled defiantly at a possible enemy or raised in a diapason to the sunrise or in a ritual of worship to the full moon, is the most fearsome sound of the jungle. As one zoologist has said: “It’s a combination of the bark of a dog and the bray of a mule magnified a thousand-fold.” It can be heard, and clearly discriminated, eight or ten miles away. Some say that the howl not only sounds like the voices of fiends let loose from the pits of Hades, but that the appearance of the animals themselves is just about what one would picture for the infernal beings. The loudness and carrying power is due to the monkey’s peculiar throat structure, which enables the sound to reverberate. This throat structure is the weapon which nature has provided for the animal and it has enabled him to more than hold his own in the endless struggle for survival of the fittest. Even more, it has made him supremely contemptuous of all lesser-voiced creatures, such as men on foot or men in airplanes at whom he howls defiantly.
Of all apes or monkeys, the howler probably looks the least like his distant cousin, man. He is at very best a grotesque caricature of a chimpanzee or a gorilla. Attempts have been made to oust him from the monkey race altogether and to degrade him to the pseudo-monkeys, the lemurs. But in biology there is nothing to justify this.
Fortunately for students of animal behavior the howler is a daylight animal. He usually goes to bed at sundown and stays there until sunrise, except on occasions when the full moon awakens him and arouses some uncontrollable frenzy which finds expression in the weird howling. So about everything he does is open to observation.
The creatures remain about the least acceptable of the monkey and ape race in human company. The feeling apparently is reciprocal. The howler is an almost untamable wild animal. He never will dance at the end of a hurdy-gurdy grinder’s leash, and seldom will be on exhibit in zoos. He dies quickly in captivity, but only after becoming such a nuisance with the howling of a broken heart that zoo keepers are glad to be rid of him. Only one specimen has been kept in captivity at Barro, Colorado—a baby rescued by one of the Indian guides after she had fallen out of a tree. This happens not infrequently to the little howlers before they have mastered the acrobatics of the forest canopy. They are not climbers at birth, any more than seals are able to swim.
In the strange treetop realm among his own the howler is a much more engaging personality than he appears down below. He is the “man” of the green canopy 100 feet above the earth. He is the dominant creature, intellectually if not always physically, and he appears to have evolved a complex form of social organization.
From two to three hundred of the big black monkeys inhabit Barro, Colorado. They are split into groups of from ten to twenty individuals. These groups are probably extended families, each consisting of two or three adult males, a few younger males, and the remainder females and babies. Each clan possesses an area of from 250 to 500 acres. This is the “home town” and few of the monkeys ever stray across its borders.
Within such an area are “roads,” path of long branches and heavy vines by which a troop can pass easily from one treetop to another. These same ways are maintained year after year. The howler requires solid footing. Despite his lofty, wind-tossed habitat he is not much of a gymnast. For one reason, his body is too heavy. He appears quite clumsy compared with his lighter, more volatile relatives, the spider monkeys of the same high realm. Howlers, for example, very seldom have been observed leaping from tree to tree. Occasionally, probably only in cases of dire necessity, a swinging vine may be used as a trapeze. Any aerial acrobatics, however, appear far from this monkey’s ideas of good sport.
Through its allotted area a group usually moves in single file, the adult males leading the way and the females with young clinging to their backs or breasts bringing up the rear. The treetop roads seldom are wide enough to permit two monkeys to move abreast. When any of the troop drops behind, the procession is held up to wait for him. If he does not appear in a few minutes scouts are sent back to find out what has happened. About the worst to be anticipated is that a mother has dropped her baby. She immediately will descend to retrieve it from the ground or, as is more likely, from some of the lower branches which have broken its fall.