For the early-morning visitors to the ancient Primate House at Lincoln Park Zoo, there is no indication this crisp October day that they are about to learn a wonderful and not too well publicized truth: Chicago has become the gorilla capital of the world.

G. gorilla gorilla. The western lowland gorilla from equatorial Africa. Sinbad. the fierce-looking giant male who occupies two connecting cages, is a worthy representative of his species. Morosely beetle-browed, he surveys the passing parade of visitors on the other side of the thick, protecting plate glass. In Cameroon, where Sinbad was captured as a baby, big silver backed males like him lead groups of 15 to 30 gorillas, deciding where the group should sleep and what shrub is safe to eat.

Gorillas need fear no predator except for man. C. gorilla gorilla is fast vanishing. There are said to be fewer than 5,000 of them left in the wild. In Gabon, people hunt them for food; new factories and railroads invade their habitats. In Cameroon, farms and logging destroy their rain forests. By the year 2000, say the naturalists, the last gorilla in the wild will be gone.

But wait; A marvel is happening.

Not until late 1956, at the Columbus (Ohio) Zoo, was a gorilla born in captivity. In 1977, a world survey covering the previous 15 years recorded 635 western lowland gorillas in 137 zoos and research institutions, only 138 of them born in captivity. Traditionally, gorillas reproduced poorly in zoos. Their jaillike cells and their solitary confinement were not conducive to teaching gorillas how to be gorillas Mothers didn't learn how to nurse their young. "Aunties" weren't around to help with the baby-sitting. Couples didn't even know how to mate.

From January 1, 1962, until June 30, 1970, a sparse 33 baby gorillas around the world were born in captivity. But zoos then began mending their ways. In the next six years 105 gorillas were born. As of last year the US. gorilla population had reached 191, of which 131 were born in captivity. Instead of jail cells the zoos had begun housing their gorillas in "habitats," like Lincoln Park Zoo's $ 3.2-million Great Ape House, opened in 1976, which permits its gorilla colony to cavort on three-story high climbing poles and live in groups of as many as 13 animals. The baby gorillas here have no trouble learning how to be gorillas.

Assistant zoo director Dennis A. Meritt, Jr., can hardly contain himself as he re counts his zoo's good fortune: Since 1970 19 gorillas have been born at Lincoln Park; 12 of them are alive. Not counting Sinbad, the zoonow has 22 gorillas, including a female on indefiniite breeding loan from the Milwaukee Zoo (with both zoos sharing equally in her offspring). Best of all, Lincoln Park has a highly fertile male named Kisoro on loan to a zoo in Canterbury, England. He is a champion producer of babies, with two of his male offspring already in Chicago; more will be coming from England when they are old enough.

"We now have three very nice groups of sexually mature gorillas producing babies," says Meritt. "Because of the males we're getting from England, they won't be too inbred. New great-ape houses are being built all over the world, but there are no animals to stock them. When we have enough animals in the right ages and sexes for the next 25 years, we'll declare a surplus. We won't relinquish ownership of the animals, but we'll put them on breeding loan to share in the offspring. Then, God forbid, if a virus or an unknown disease strikes us in Chicago we'll be protected, with animals all over the world."

Yes, Lincoln Park Zoo is in the catbird seat. When, in the late 1960s, zoo director Lester Fisher began building the present collection of apes, he had to pay only $2,500 to S3,000 for wild-caught baby gorillas. These can no longer be imported: ~they are protected by the U.S. Endangered o Species Act and by the Convention on International Trade in Endangered Species. Last year the Cincinnati Zoo sold a young female to the San Francisco Zoo for $100,000. Is a prime breeding adult like Lincoln Park's Otto worth one million dollars? "It's pointless to speculate," says Fisher. "He's not for sale and won't be." Dennis Meritt says, however: "Without question, ours is the largest collection of gorillas in the world, the most reproductive, and therefore the most valuable."

The zoo's population explosion, which accelerated with the move to the new Great Ape House, left Sinbad behind. A virgin, and the second oldest gorilla in captivity (he came to the zoo 34 years ago), he would snap at females instead of wooing them. "If we had moved him, he would only have displaced one of the three young breeders we had," says director Fisher. "Also, he had spent nearly his entire life in the Primate House. The move would have been just too confusing. So we kept him where he was."

Visiting Sinbad is visiting gorillas as they were a generation ago. Sinbad actually occupies the old quarters of Bushman, the world's most famous gorilla, who died on January 1, 1951. I was working rewrite on the Chicago Sun-Times that New Year's Day and wrote his obituary: Bushman the gorilla who won the heart of Chicago and the nation, died in his sleep Monday morning at Lincoln Park Zoo.

The world's most famous gorilla apparently suffered a heart attack. For six months 22-year-old Bushman had battled the crippling effects of arthritis, heart disease and old age.

His millions of friends were shocked. Hundreds of visitors crowded into the zoo monkey house and stared at his empty cage.

Zoo Director R. Marlin Perkins told them: "This is a great blow to all of us."

You can inspect Bushman's stuffed remains at the Field Museum and see how magnificent he was: 575 pounds, six feet two inches tall, an arm span of ten feet. The American Association of Zoological Parks and Aquariums called him "the most outstanding animal of any zoo in the world and the most valuable."

But Bushman had his dark side. I remember walking behind his cage and having to duck as he wound up like a baseball pitcher and splattered me with his fecal matter—one of his standard and least amusing tricks. Photographer William Sturm's face turned purple when Bushman seized his necktie and refused to let go; a keeper had to pull out his pocket knife and slash the tie in half so that Sturm could get free.

Sinbad, too, has his dark side. At 500 pounds—one of the world's largest gorillas—he has been known to pick up a tractor tire that weighs several hundred pounds and hurl it into the back bars at a passing keeper. He, too, throws feces, and that can hurt. One day he flung a tiny piece of carrot at the front glass with such velocity that it passed right through like a bullet. A heavy steel barrier has been erected in back of the cage to protect the keepers.

Pamela Jensen, blond, blue-eyed, and only five feet three inches tall, has worked with Sinbad for nearly five years; she personifies the new generation of zoo keepers with her degree in physical anthropology. "I never let my guard down," she says. "He still makes grabs for me."

But Sinbad has his gentle side. In the morning, when Jensen gives him his threetimes-daily cocktail with nonfat powdered milk from a two-quart oil can (containing every conceivable vitamin, and nine aspirin-and-Maalox tablets for the terrible pain of arthritis that afflicts his hips), he makes a purring sound as he bangs on the bars, running from one side of the cage to the other and trying to get Jensen to do the same.

"He's a very dignified animal," Jensen says. "If he sees that you saw him slip while playing on his tire, he shudders; if you laugh, it's terrible." For treats Jensen buys him bismarcks from Dunkin' Donuts, putting them in a paper bag that he loves to rummage through. "For a while, to stimulate him, we showed him TV soap operas, with lots of close-ups of people. But he lost interest. Then we played country-and-Western songs for him. Best of all, he likes to play with bits of hose and parts of a burlap bag. He arranges them in a semicircle and sits in the middle; in the wild, gorillas make nests like this, using vegetation."

Each day, except Sunday, when he diets, Sinbad puts away 18 pounds of food (cut back from 26 pounds because of his arthritis). Along with his morning milk he is given a pound of high-protein monkey chow and three pounds of ground-up horsemeat. At 11 a m. he gets his lunch: a "salad" of two apples, three bananas, a handful of green beans, three carrots, a celery stalk, a large bunch of grapes, a lemon, two heads of lettuce, eight oranges, half a sweet potato, and a cup of raw peanuts or sunflower seeds.

Although his outdoor cage is open to him for the warmer months of the year, Sinbad usually goes there only in the early morning when there are no people on the zoo grounds. If a visitor approaches he will go back inside; occasionally, having picked up a stick or a stone, he will tap with it on the bars until Pam Jensen runs over with a handful of grapes and says, "OK, let's trade." Instead of holding the grapes out for him to pick up from her outstretched hand,

The Great Ape House facts

The only nonprimates living in the Great Ape House are some 20 finches, a cardinal, and a South American red-breasted blackbird, which coexist with the gorillas but not with the chimpanzees. "The dumbest of the birds have been eaten by the chimps," says senior keeper Jim Higgins. "The chimps trap them by setting out monkey chow as bait and then grabbing any birds that come close."

When it comes to sleeping, gorillas like to hit the hay as soon as it gets dark. On the rare occasions when the Lincoln Park Zoological Society throws a party in the ape house, the gorillas are kept up late. "And then they're crabby all of the next day," says keeper Higgins.

Otto, the prime breeding gorilla of the ape house, is named after the late Otto Kerner, a former Illinois governor who served a prison term for income-tax evasion. The late Franklin Schmick, a Chicago Park District commissioner who donated Otto to the zoo, was a close friend of Kerner's. Jensen throws them into his mouth from a safe distance on the other side of the bars. Sinbad is just too strong to be trusted. In this respect he is not unlike the late Gargantua, the famous Ringling Brothers and Barnum & Bailey circus gorilla, who played tug of war with a dozen roustabouts. "He could always win if he wanted to," circus owner John Ringling North said, "but each time the gorilla threw the end of the rope out he would shorten it, hoping thus to lure the human player closer so he could grab a bite." Gorillas have huge canine teeth. .Life in the Great Ape House is much different from that in the old Primate House, for besides a couple of families of orangutans and chimpanzees there are three gorilla groups living behind laminated safety glass 1 5/8 inches thick that costs $4,000 a pane and can withstand an impact up to 1,300 foot-pounds. The glass enables visitors— some four million a year—to get very close to the gorillas, even following them upward on a spiral ramp as the animals climb three stories on an arrangement of poles and ropes.

One of the most popular gorilla habitats (zoo officials hate for the word "cage" to be used in this building) holds the smallest ape group, consisting of only two gorillas: Otto, a splendid 450-pound male captured as a baby in Cameroon in 1965, and Mumbi, a 200-pound grandmother born in 1961. Otto is the zoo's champion ape breeder, having fathered ten of the 19 gorillas born here. But there is a reason for Otto's being kept alone most of the time, with only a succession of female companions.

"He's too mischievous," says senior keeper Jim Higgins, a bearded man of 36 who has helped care for Otto since 1968. "He's been known to snatch babies from the arms of his ladies [gorilla babies are very small at birth, weighing only three to four pounds] and put them into his mouth. Then he climbs up high, with only a tiny leg or arm sticking out between his big teeth. It's a horrible sight but he means no harm; he's only teasing the mamas. Just like when he pokes the ladies to get them to scream and run after him."

Otto may not mean any harm, but as the biggest gorilla in the Great Ape House he's not to be crossed. "I've seen him tug at the one-inch manila ropes hanging from the ceiling of his habitat [they're up to 1,000pound test] until they snap apart," says Higgins.

That's why Otto's escape last summer was so worrisome. Somehow, around nine o'clock on a July morning, he managed to scale an 11-foot barrier enclosing the outdoor habitat atop the ape house, avoid two electrically charged wires, and embark on a 30-minute stroll around the zoo grounds. Getting a huge gorilla back into his cage takes some doing. When, in the 1940s, Bushman escaped into the service corridor behind his cage, he bit his long-time friend and keeper Eddie Robinson, who finally frightened him back into his cage by waving a long garter snake at him (gorillas are said to have an irrational fear of snakes). When, in the late 1960s, Sinbad got into the same corridor, separated from the outdoors by only a thin screen door, he had to be put to sleep with a tranquilizer gun.

"In Otto's case, what I was afraid of," says keeper Higgins, "was some cop coming along with a .357 Magnum and wasting him." There was also the possibility that Otto, frightened, might literally tear some passer-by into pieces; gorillas are strong enough to do just that. Instead, zoo veterinarian Dr. Thomas P. Meehan, 30, saved the day, driving up in a truck outside the Lion House, where Otto was resting. Meehan, who practices shooting tranquilizer darts at small paper boxes from a distance of ten or 12 feet, took careful aim at Otto with a Palmer gun and winged him in the quadriceps muscle of the left thigh. Within five minutes Otto was sound asleep. Ten strong men lifted him onto a litter, and Otto was driven back in the truck to his home in the Great Ape House.

With Otto asleep, Dr. Meehan had a rare chance to examine an otherwise unexaminable patient. Blood was drawn for a variety of laboratory tests and his right eyelid was injected with tuberculin test material. Gorillas are highly susceptible to tuberculosis. "Normally, the tuberculin test is done on an arm, but to check for a positive inflammatory reaction three days later would require putting him to sleep again," says Dr. Meehan. "By doing the test on the eyelid you can easily see if it's swollen."

If Otto is not to be trusted with babies, another big silverback named Fred is just the opposite. Also from Cameroon, Fred, who is 22 and weighs 365 pounds, loves infants, allowing them to crawl on his head and poke fingers in his eyes. Because of his steadiness, Fred is permitted by zoo officials to be the leader of the largest ape group of 13 gorillas, of which ten were born in captivity. The gorillas occupy two connecting habitats, and their daily activities give zoo visitors a pretty good insight into what gorilla life in the wild must be like.

Visiting the gorillas recently, I saw the youngest child in Fred's group, Matadi, sired by Otto and born last February, getting a gymnastics lesson from her mother, Helen, who is wild-born. Gorilla babies remain babies until about age three, and until then are carried around and breast-fed (gorilla milk, by the way, is relatively low in cholesterol, with only 30 to 50 percent of the butterfat content of human or cow's milk). Helen puts Matadi down and, to get her to walk, moves away a few feet. Matadi, alarmed, grunts " Oooh-oooh-oooh" and stumbles after her mother. Gorillas mature sexually at about seven, but physically and intellectually they are adolescents until 12 or so. In the wild, when mature, they usually leave the group in which they grew up to seek out another one; this avoids inbreeding.

The pecking order of gorillas is constantly shifting. Two of the younger apes in Fred's habitat commence a screaming dominancy fight, showing their fearsome teeth and chasing each other around the habitat. Enough is enough. Fred ambles over, surprisingly swift on all fours for such a big ape! and barks a warning. The brawlers immediately desist; otherwise Fred might lash out with a slap. Like most dominant silverbacks, he values peace and quiet.

Besides his warning bark, Fred has some half dozen other vocalizations (as zoo people call them) in his vocabulary. " Wah~seah~s~oowoo," for example, is a distress call. When keeper Higgins hears this, he calls back the same cry as reassurance.

Fred, like all gorillas, is probably smart enough to enroll in elementary school. Koka, a lowland gorilla owned by the San Francisco Zoo, was taught 645 of the hand signs that deaf people learn; when given the Stanford-Binet l.Q. test, several times she scored between 85 and 95, nearly average for a human. Perhaps she would have scored higher if there had not been a built-in human cultural bias in the test. For example, asked where she would take shelter from rain (hat, spoon, tree, or house), Koka picked "tree" and was marked wrong! (The correct answer was given as "house," though, to a gorilla, a tree might seem like the right place.)

Watching the gorillas is a joy. Twice a day recorded thunder booms out in the ape house and "rain" falls for five minutes (this helps keep the humidity a high 60 to 80 percent; the temperature is about 72 degrees Fahrenheit). A class of kindergartners laughs in delight as Fred climbs directly under a rain spigot and takes a shower, hanging by one hand as he washes an armpit.

One of the younger stars of the habitat is BaBeC (pronounced bay-bec and donated by Barry and Beverly Crown), a male nearly three years old who is so active that you'd never guess he was almost crippled about 18 months ago. The veterinarian, Dr. Meehan, was called to the habitat when BaBeC was heard crying. The baby gorilla could not walk on his left leg. Using a tranquilizer blowpipe, which is suitable for the smaller animals, the vet put Benga, the baby's mother, to sleep and then the baby, who was removed to the emergency room of Children's Memorial Hospital. BaBeC was found to have fractured his left hip, probably in a fall. He was taken back to the zoo along with a team of two pediatric surgeons and a surgical nurse from Children's Memorial. At the zoo hospital they operated on the hip, drawing it together with a huge lag screw and a plate. Today BaBeC's hip is normal, as Dr. Meehan proudly demonstrated to me on an X-ray film. I could not help noting how much like a human baby the young gorilla looked on the X ray.

Some 50 men and women—veterinarians, pediatricians, gynecologists, and so on—serve on the zoo's unpaid medical advisory board. They include Chicago's ranking medical specialists. Dr. Sandra Olson, a neurologist, who this year was named chief of staff of Northwestern Memorial Hospital, was called in after Fred had been observed periodically dragging a foot. Dr. Olson had to be content with a limited examination, letting a keeper make Fred move back and forth. She had no doubt, however, that Fred had a disc problem; Fred now gets the same medicine that Sinbad gets, aspirin mixed with Maalox.

A couple of years ago Fred was put to sleep with the Palmer gun and with an electrical device was made to ejaculate. For reasons that scientists can't comprehend, many male gorillas are infertile. A scientist at Brookfield Zoo reported last year that 13 of 26 electro-ejaculated gorillas were sterile or probably so. Poor Fred: Such a good den father, but a real father only once (of Jo Jo, born in 1980 to Leonore). Keeper Jim Higgins says that less than two percent of Fred's sperm proved viable when he was tested.

Low sperm count or not, Fred is a good model for the young males in his habitat. Thumping his chest in proper gorilla fashion, he is impressive, I note, to two young males, Kamboula and Kounda, half brothers born in England to their American father, who is in Canterbury on breeding loan.

.They watch Fred appreciatively, but politely, in the usual gorilla fashion, avoiding threatening direct eye contact. A keeper takes me up to the third level, which is closed to the public and where Kamboula and Kounda like to climb. "They really are fond of people," another keeper, Peter Clay, tells me as he accepts a bit of apple that Kounda pokes through the bars. Kamboula grunts a greeting to keeper Gene Grzanka. who grunts the same sound back. The animals let me stroke their curiously human fingers, a bit like E.T.'s, and they gently stroke mine.

There is no need to worry about anything nasty being thrown at you in this ape house. Morale is far higher here than in the old Primate House. The gorillas even help out with their own care. I watch as one of the keepers, unable to retrieve a clump of wet straw in a far corner of the habitat. points to it and calls to a young gorilla "Bring it over here!" Quickly, the ape retrieves the straw and gets a banana in exchange.

The third group of gorillas is headed by Frank, who at 325 pounds is small for a sil verback but has perfect conformation. Although he has fathered six children, of whom three are living, Frank, too, has medical problems. Through the years he has had a series of small strokes temporarily affecting both his right and left sides. Concluding that he suffers spasms in the arteries carrying blood to the brain, his neurologist, Dr. Olson, of Northwestern Memorial Hospital, has prescribed Persantine, a mild anticoagulant. The medicine seems to work.

Five females live with the 18-year-old silverback, and watching them gives one an idea of gorilla child-rearing practices. Zoo director Fisher acknowledges that too often zoos have removed newborn gorillas from the care of their apparently inept mothers and hand-raised them as they might a human infant. "What happens then," says Dr. Fisher, "is that you get a gorilla who doesn't know how to be a gorilla."

Kivu, a female born in 1978 to Benga, was ignored by her mother and had to be reared at first in Dr. Fisher's home and that of his assistant director: "Diapers, formula, pediatricians, the whole bit," says Dr. Fisher. "After a stay at the zoo nursery, Kivu was given a chance to learn gorilla behavior by having her sit just outside the habitats and watch what was going on. Then we turned her over to Debbie, an 'auntie' who had never had a baby of her own and who taught Kivu how to be a gorilla."

Dr. Fisher credits his family pediatrician, Dr. Martin Hardy, "with giving me the backbone not to immediately pull gorilla babies from their mothers. When you see a tiny three-pound baby with its huge mother, it's natural to worry that she'll hurt it or fail to nurse it. Dr. Hardy convinced me that a couple of days without milk wouldn't hurt a healthy baby and that by keeping a baby with its mother it would have a chance of ending up as a real gorilla."

Only last April the zoo had a disappointment when Frank's mate Terra, who is on breeding loan from the Milwaukee Zoo, failed to nurse a newborn daughter. After five days, the mother was anesthetized and the baby was taken to the assistant zoo director's home temporarily. Two weeks later it was transported to Milwaukee, sirens screaming, by a Wisconsin caravan consisting of a state police car, a TV van, and several Milwaukee Zoo vehicles.

A gorilla's period of gestation is about 260 days, a bit less than that of a human. Guessing whether a gorilla is pregnant or not takes some doing. I watch a pregnancy consultation. Benga, who has been making it with Fred, looks pregnant to a visiting obstetrician, Dr. Janice Asher, an instructor at Northwestern University Medical School, but appearances can be deceiving.

"Benga's been a mother twice before and has lost her girlish figure," says keeper Jim Higgins. "She just looks pregnant."

Dr. Asher retorts: "Just like some women."

A keeper scoops up some of Benga's urine from the habitat floor and seals it in a bottle; this is the only way a specimen for a laboratory test can be obtained.

A female gorilla's cycle is much like a human's, and gorillas usually do their mating during this monthly period—though aggressive silverbacks like big Otto sometimes appear to force themselves on unwilling females in a show of dominance. Actually, the mating process seems something like a miracle in Otto's case, because the sexual organ of even the biggest gorilla is never more than an inch and a half long.

The crowd gathered in front of Otto's habitat seems unaware of a change in the big ape's behavior. For an hour he has been teasing Mumbi, his companion, by poking her and getting her to chase him around the habitat. Now Otto starts beating his chest and making runs past Mumbi, who is sitting on a perch, her feet dangling. Otto reaches out his powerful gorilla arm and gently tickles Mumbi's toes. Mumbi reaches down and touches Otto's hand. Then, getting off the perch, she presents herself to him.

A nursery school teacher, here with her class of youngsters, is embarrassed. "C'mon, kids," she calls, tugging at the hands of two children who seem entranced. "We've got to go."

Head keeper Jim Higgins makes a written note of the happening. Who knows? Two hundred sixty days from now, Chicago's reputation as the gorilla capital of the world may be enhanced. END

The gorillas at Brookfield Brookfield Zoo's gorilla colony is of modest size compared to Lincoln Park's, but the apes live in an extraordinary environment that has visitors convinced that they're peering into a rain forest in West Africa.

Instead of being confined to narrow cages, the animals can roam freely in their 400,000cubic-foot section of Tropic World, a ninemillion-dollar building the length and width of one and a half football fields. It is also occupied by two dozen monkeys of various species, a variety of tropical birds, and a placid pygmy hippopotamus named Sassy.

At night the keepers blow a whistle to call the primates to their private holding cages for the evening meal. By day, when they are released into the main environment, the gorillas occupy themselves by seeking out treats of hay, raisins, and sunflower seeds that have been hidden by keepers all through the forest, making them forage as though they were in the wild.

The setting is realistic, with a mixture of live tropical plants, cement-sprayed trees, and vines made of epoxy-covered rope. There is a small mountain for 22-year-old Samson, a 450-pound male gorilla, to climb and a stream for him to wade in. Samson, on breeding loan from the Buffalo Zoo (a courageous act by Brookfield because the big gorilla had never been capable of fatherhood in his many years in New York), has nourished here, having mated with both Alpha, 22, and her daughter Babs, age eight. Babs bore a daughter, Aquilina (who was a year old on October 1 5th), while Alpha was carrying another daughter of her own, Becky, who will be a year old on December 15th.

The fascinated visitors can get as close as eight feet, unseparated from the animals by bars or glass, to the domestic scenes of gorilla life that unfold all day. In a few months the four apes will be joined by Mesou, a 27-yearold female gorilla on loan from the Detroit Zoo. A 230 pounder who has never repro duced, she is being kept in a holding area until ready for the big habitat, where, in the African section, it rains and thunders several times a day.

Tropic World Africa, which opened this past spring, will expand next May to include animals in an Asian background and again in 1984 for some from South America.

J. S.