Dwindling Breed

Sex and the single gorilla

Poor Omega. Once the pride of the Brookfield (Ill.) Zoo, he is now an outcast. Rejected by two female companions, the hefty 450-lb. gorilla sits alone in his cage, forlornly munching on alfalfa or taking a lackadaisical swing on the rubber tire hanging from his ceiling. Omega's problem is that he is sterile.

Along with chimpanzees and orangutans, gorillas are man's closest kin. They are also remarkably susceptible to human ailments, including mumps, measles, even ordinary colds; and although Omega has never seemed seriously ill, his sperm count is now nil. No one is sure why. It could be his weight (obesity can interfere with gorilla lovemaking); it could also be years of sexual inactivity. Whatever the reason, says Primate Curator Benjamin Beck, Omega's condition is all too common among gorillas in captivity, and that has scientists worried.

No more than 12,000 gorillas still roam freely in their native Central Africa, and many experts feel that wild gorillas could be all but extinct by the year 2000. That leaves only zoos, primate centers and wildlife preserves as repositories of these greatest of all apes. Yet the 600 or so gorillas in captivity have been extremely poor breeders. Only about 100 animals have been born in North America in the past decade, hardly enough to ensure survival of the species.

These "second-generation" gorillas have an even lower reproductive rate than the ones brought in from the wild. Part of the problem, according to primatologists who met in Atlanta last month to discuss gorilla fecundity, is that baby gorillas have often been hand-raised by solicitous zookeepers. So they never learned the requisite gorilla social graces, including the nuances of courtship. Says James Doherty of New York's Bronx Zoo: "You get a gorilla that thinks he's people and not a gorilla."

Zoos will also probably have to give up the custom of pairing baby male and female gorillas. The practice may make them feel and act more like brother and sister than lovers when they reach sexual maturity (at about age eight). At the Cincinnati Zoo, for instance, a male named Mgolo delighted in pummeling Penelope, who had shared a cage with him since infancy. She refused to breed with him. Only after she had been moved in with another couple did she find her true love. As a result of this and similar matchmaking, the zoo now has 14 offspring.

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