Through a Window (17 page)

Satan moved on again, but when he looked back and saw the
others were not following he paused: he was not prepared to go on by himself. After a moment, however, Jomeo followed, then the rest.

Ten minutes later the soft whimper of an infant was heard just ahead. Instantly, after glancing at each other, the males and Gigi raced towards the sound. Just as they reached a tall, sparsely foliaged tree a female leapt down. She might have got away, but her infant, between two and three years old, was still up in the branches, screaming now in fear. The mother raced back, seized her child and once more hurled herself to the ground. But she had lost valuable time—the Kasekela patrol was upon her. Goblin was the first to seize the stranger, hitting and biting her and stamping on her back. A juvenile, who had also been in the tree, quietly climbed down and vanished into the dense bush. Satan and Mustard leapt to join Goblin as he continued the attack, and a moment later Figan and Jomeo hurled themselves into the fray.

During this fierce assault, Evered seized the infant and charged off through the bushes, flailing it against the ground as though it were the branch of a tree. Then, hurling the little body ahead of him, he turned back, racing to join the other males who were still attacking the mother. Gigi was there too, on the outskirts of the mass of screaming, yelling bodies, getting in a hit whenever opportunity offered.

Some ten minutes after the start of the attack the female managed to pull herself free and, still screaming in terror, clambered into a tree. Goblin was the only male who followed. He attacked her briefly, then watched as Gigi, obviously determined to have the last word, climbed up and delivered a final series of hits. The stranger pulled free, took a huge leap to a neighbouring tree, another to the ground, then headed towards her infant, who was still screaming in the undergrowth. The whole encounter had lasted some fifteen minutes. There was a great deal of blood on the flattened vegetation where the worst of the fighting had taken
place, and some under the tree where Goblin and Gigi had meted out the final punishment.

For the next five minutes the Kasekela chimpanzees, in a state of excitement that bordered on frenzy, charged back and forth around the scene of conflict, dragging and hurling branches, throwing rocks, uttering the deep, low-pitched hooting calls that sound like roaring. Eventually, still in a noisy and boisterous mood, they turned and moved back the way they had come.

At least once a week the Gombe males, usually in groups of not less than three, visit the peripheral areas of their community range. There is no clearly marked boundary between neighbouring social groups; usually, in fact, there is an area of quite extensive overlap between them. When the males discover some good source of food in such an overlap zone, they often go back the next day to feed, accompanied then by females and youngsters. On expeditions of this sort, the chimpanzees typically ascertain the whereabouts of their neighbours before commencing to feast. Thus when they reach some high ridge overlooking neighbouring territory the expedition members pause and very carefully scan the country ahead. If all seems clear they usually utter loud pant-hoots, then listen intently. Only if they hear nothing, or if there is a reply from very far away, will they advance confidently and begin to feed.

Sometimes, as a group of chimpanzees wanders along foraging, pausing occasionally to rest and groom, the adult males suddenly begin to travel in a brisk manner, heading towards some outlying part of their community range. This sudden sense of purpose, this air of determination, usually indicates that they are setting off to monitor the whereabouts of their neighbours. At this point mothers and young who have been travelling with the males typically drop back—except pink females, who usually tag along behind.

When patrolling males detect the presence of strangers, they begin to move cautiously, sniffing the vegetation, alert to
the slightest sound. The discovery of discarded wadges of fruit peelings or abandoned termite fishing tools arouses immediate interest. If a fresh sleeping nest is seen, the males usually climb up to investigate it thoroughly, then display wildly through the branches until it has been virtually destroyed. If they actually see chimpanzees from the neighbouring community their response will depend on the size of that group relative to theirs—particularly with regard to the number of adult males. If one of the groups is larger than the other, or has more adult males, then the smaller one typically retreats discreetly and silently to a safer place. If the other males notice they will call loudly and give chase but, provided there is more than one male in the fleeing group, the pursuers will not try to catch up: they are content simply to provide a show of strength. If honours are about equal—with similar numbers of males in each patrolling group—then members of both sides, usually keeping several hundred yards apart, hurl threats at each other. First one group, and then the other, performs wild displays, charging through the undergrowth, slapping and stamping on the ground, drumming on tree trunks, throwing rocks, and all the while uttering loud, fierce calls. Finally, after half an hour or more, each side retreats towards the safe central part of its own home range. This vigorous and noisy behaviour serves to proclaim the presence of the legitimate territory owners and to intimidate the neighbours. Fighting is not necessary.

It is when two or more males encounter a lone stranger, or a couple of stranger females with infants, that fierce and brutal attacks take place. Indeed, if patrolling males hear the calls of an infant in some outlying part of their range and suspect the presence of a mother from a neighbouring community, they sometimes stalk her, persisting for an hour or more in their attempt to hunt her down. And, if they are successful, they will attack. A stranger male may be attacked also, but during the course of our years of research at Gombe we have observed only two,
relatively mild, attacks on males from neighbouring communities, as compared to eighteen severe assaults on stranger females. Males, after all, are far more dangerous adversaries, particularly when they are strangers and their strengths and weaknesses unknown. Of course a lone male could be defeated by a group of males—but he might inflict some serious injuries on one or more of his aggressors during the battle. A female, especially if she is protecting an infant, poses no danger to her assailants.

Why are these females attacked so savagely? In some mammalian societies—those of lions and langur monkeys, for example—a male who has defeated the leader of a group and taken over the females will sometimes kill all small infants. With luck, his newly acquired females will become sexually receptive sooner than would have been the case had they weaned their infants normally. The new leader will then have a double advantage: first, he will be the father of all subsequent babies born into his group; second, he has eliminated some of the offspring of his defeated rival who, had they survived, would have competed with his own. In terms of evolutionary theory, this exercise will be to the reproductive advantage of the killer male if it leads to a higher proportion of his biological kin in future populations than would otherwise have been the case.

The attacks observed at Gombe, however, were very clearly directed at the adult females themselves. Although there were four occasions when infants were, in fact, killed, each time it seemed that this was incidental to the savage assaults on their mothers. Whenever it was possible to get a good view of the victims after they had escaped we could see that they had been badly wounded, whereas their infants, except for the unfortunate four, seemed to be unharmed. It would be relatively easy for even one male on his own to seize an infant from its mother, and kill it, if that was his goal. It seems, then, that the attacks are an expression of the hatred that is roused in the chimpanzees of one community by the sight of a member of another. Strang
ers of either sex may trigger this hostility, but the unthreatening females are attacked far more often. In this way males dissuade them from moving into their territory—if, indeed, they survive—and food resources within the community range are protected for their own females and young.

There are, however, certain times when females are safe from savage intercommunity aggression of this sort. Late adolescent females typically move into neighbouring communities during periods of oestrus. And not only are they tolerated by the adult males there but, when fully pink, they may be actively recruited by patrolling males—who clearly find them highly sexually stimulating. Sometimes a young female remains in the new community after becoming pregnant. This is a tough decision. For one thing, her presence will be intensely resented, at least to start with, by the resident females. For another, she is effectively severing all ties with her family and the companions of her childhood since, once she has given birth, she will not be able to return to her own community. If she tried she would run the risk of being brutally attacked—unless, again, she were fully pink. We have observed a few encounters between community males and stranger females in oestrus and, although there were some attacks, there were many copulations also. But such incidents are rare—most females are carefully guarded by their own males when pink.

There is absolutely no question but that intercommunity encounters are highly attractive to some of the males, particularly when they are between fourteen and eighteen years old. Once I followed as Figan, Satan and young Sherry travelled slowly along the southernmost ridge of Mkenke Valley, at that time part of the overlap zone with the powerful Kalande community to the south. Suddenly Figan stopped, hair on end, and staring southward gave a loud call of alarm. I followed the direction of his gaze and there saw a group of at least seven adult chimpanzees. Obviously they were members of the Kalande community and
now, alerted by Figan's call, they began to display, vigorously and noisily.

The three Kasekela males ran silently northward for a short distance, then stopped and looked back. As the strangers displayed again, moving in our direction, Figan and Satan turned and fled in silence, back to safety. But Sherry, with adolescence just behind him, did not follow at once. He stood watching the advancing strangers, absorbed and fascinated. Only when two adult males charged to within fifty metres did he turn and run after his companions. And later in the day he left Figan and Satan and returned, by himself, to the Mkenke Valley ridge. There he climbed a tall tree and sat, staring southward, for over half an hour. It was as though he simply had to have just one more look.

Another young Kasekela male, Sniff, once taunted a large group of Kalande chimpanzees, including at least three fully adult males, quite by himself—his two companions had fled. The Kalande group was in a shallow, steep-sided ravine, calling loudly and charging about in the undergrowth. Sniff, uttering deep roar-like hoots, performed a spectacular display along a trail near the top of the ravine. As he charged he hurled at least thirteen huge rocks down onto the strangers. An occasional missile—a stone or a stick—flew up from the undergrowth below, but they fell far short of Sniff. Only when two Kalande males raced towards him did Sniff retreat. And he was still roaring his defiance, still slapping and stamping on the ground and drumming on the tree trunks, when he caught up with his chicken-hearted companions.

1974 marked the start of "the four-year war" at Gombe. Ten years after I arrived at Gombe, the community whose members I had come to know so well began to divide. At that time, towards the end of Mike's reign as alpha, there were fourteen fully adult males: six of them, including the brothers Hugh and Charlie and my old friend Goliath, began to spend more and more time in the
southern part of the community range. Sniff, who was an adolescent at the time, and three adult females with their young, also became part of what we called the "southern sub-group." The "northern sub-group" was much larger, with eight adult males, twelve females and their young.

As the months passed, the relationship between the males of the two sub-groups became increasingly hostile. The northerners tended to keep out of the area used by the breakaway group, but every so often, led by Hugh and Charlie, the southern males moved northwards. And, because they almost always made such forays in a tight-knit group, and because of the fearless natures of Hugh and Charlie, the northern males usually avoided them. Still, though, the two oldest of the northern males, Mike and Rodolf, sometimes wandered about peacefully with Goliath, the oldest southerner.

Two years after the first signs of a split, it was clear that the chimpanzees had now become two distinct communities, each with its own separate territory. The southern "Kahama community" had given up the northern part of the area where it had once ranged, while the "Kasekela community" found itself excluded from places in the south where it had previously roamed at will. When males of the two communities encountered one another in the overlap zone between the two, they typically hurled noisy insults at each other, displayed long and vigorously, then retreated, each side back into the safe heartland of its own newly demarcated territory. But even then the three oldest males sometimes renewed their friendship.

For a year things continued in this vein. And then came the first brutal attack by Kasekela males on a Kahama male. It was observed by Hilali and one of the other field staff. The assault began when a Kasekela patrol of six adult males suddenly came upon the young male, Godi, feeding in a tree. So silently had the aggressors approached that Godi was not aware of them until they were almost upon him. And then it was too late. He
leapt down and fled, but Humphrey, Figan and the heavyweight Jomeo were close behind, running shoulder to shoulder, with the others racing after them. Humphrey was the first to grab Godi, seizing one of his legs and throwing him to the ground. Figan, Jomeo, Sherry and Evered pounded and stamped on their victim, while Humphrey pinned him to the ground, sitting on his head and holding his legs with both hands. Godi had no chance to escape, no chance to defend himself. Rodolf, the oldest of the Kasekela males, hit and bit at the hapless victim whenever he saw an opening and Gigi, who was also present, charged back and forth around the melee. All the chimpanzees were screaming loudly, Godi in terror and pain, the aggressors in a state of enraged frenzy.