As primates who share 99 percent of the same DNA as humans, gorillas have personalities, character traits and quirks that etch them as individuals, much like people. Some are showboats, some are shy. Some are aggressive and snappish around their peers, others are diffident and conciliatory. There even are ne’er-do-well gorillas that have a carpe-diem, devil-may-care attitude about their place in gorilla society, and others so committed to properly raising the next generation that they could be paragons of “family values” for both apes and humans. Debbie, a rotund and placid 33-year-old female at Lincoln Park Zoo, is that family-values kind of gorilla. To the humans who know her best, in fact, she may be “the most valuable gorilla in any zoo anywhere.”
Debbie is a “founder,” one of a distinguished group of nine wild-born lowland gorillas, four males and five females, that Lincoln Park Zoo purchased in the late 1950s and early 1960s. Most came here as babies and were raised to establish a captive breeding colony.
The experiment has turned out to be a long but fascinating process. Over the years, zoo visitors and especially keepers have seen the gorillas, a species humans have driven nearly to extinction in Africa, reveal behavior that eerily echoes our own. It ranges from love, jealousy, anger, glee, lust and sadness to perhaps even altruism.
As the “founders” grew up, they began breeding, with spectacular results. Their 44 children, grandchildren and great-grandchildren now account for about 10 percent of the combined North American zoo gorilla population. Only the Cincinnati Zoo, with 47 births, has had more gorilla babies.
In a zoo that takes rightful pride in getting its resident gorillas to live together in a family society closely resembling gorilla society in the wild, Debbie is prized for behavior that does not exist in the wild. When baby gorillas in the wild suffer severe injuries or when their mothers fail to lactate, the babies die. In zoos, they go to hospitals and then are hand-reared by humans for months or even years. When it comes time to rejoin their own kind, the gorilla infants are often so imprinted by human behavior that they think of themselves as humans. That can be dangerous, as adult gorillas often have no patience for self-centered, human-style infant behavior.
Taking on human-reared gorilla youngsters and coaching them in the complex protocols of gorilla life has become Debbie’s mission, and she has taken on 10 such youngsters in the last 20 years. Each time, Debbie sat patiently while a human-raised infant gorilla–scared to death of being left with a big, hairy ape–has slapped, scratched and bitten her for days. But once they come to trust Debbie, the young gorillas begin a slow behavioral metamorphosis that almost invariably leaves them as tightly bonded to Debbie as any normal infant is to its birth mother.
An estimated 3 million visitors annually go through Lincoln Park’s Lester Fisher Great Ape House, the zoo’s most popular attraction. Humans are separated from the animals by floor-to-ceiling reinforced glass windows, giving them a remarkably close-up, intimate view of gorilla life.
“You can stand a foot away from a living gorilla, each species (human and gorilla) looking right into the eyes of the other,” says Kristen Lukas, an animal psychologist hired last year as Lincoln Park’s primate curator. “If you don’t take something away from that experience, something is wrong.”
Debbie is usually little noticed by the visitors, who tend to focus on the romping gorilla babies and the regal silverback fathers. In May, after living away from him for two years, Debbie moved back in with Frank, 35, a gimpy-legged runt of a silverback leader with a vast and generous heart, another of the zoo’s gorilla “founders.” He and his harem of five adult females live in the first two glass-walled chambers that zoo visitors come upon as they enter the ape house and file to the left.
Until she returned to Frank, Debbie had been in another section of the ape house bringing up two “orphans,” sisters Rollie, 3, and Mumbali, 1. Both were pulled from their mother, Kowali, for medical reasons just days after being born; they were hand-reared by humans in the Children’s Zoo. When it came time for Rollie and Mumbali to learn to be gorillas, their keepers placed them with Debbie–Rollie when she was 13 months old, and, a year later, Mumbali at 9 months.
Now all three live in Frank’s domain, where they are likely to be found together when the ape house opens daily at 10 a.m. They are easy to spot because Debbie is the only adult gorilla tending to two infants. The gorillas, fresh from a night’s sleep in their upstairs quarters, have just come down to their freshly cleaned public quarters, the floor thickly matted with straw in which keepers have hidden favorite food treats. The gorillas spend much of their morning looking for the treats, and Rollie, Mumbali and Debbie usually sit near one another while they hunt and nibble.
Shortly after noon, the gorillas laze about, and the babies like to nap. Debbie often lies down next to the public viewing windows, and Rollie and Mumbali snuggle by her side. The young gorillas show no sign that just a few months ago each of them despised and feared her.
Sometimes Debbie interacts with visitors on the other side of the window. With adults, she may raise one of her massive arms to splay the fingers and palm of her hand against the window, inviting the human on the other side to do the same. She is especially charmed, however, by children. For them, she has been known to play a sort of patty-cake game, alternately clapping her hands and placing her palms against the window, getting children to join in, if they catch on to her game.
“She has always been fascinated by kids,” says Cathy Maurer, the ape house’s lead keeper, who has worked around Debbie and the other apes for 17 years. “When children come dressed up for `Spooky Zoo’ during the Halloween season, she glues herself to the window and looks over the costumes the kids are wearing.”
Terry Maple, the head of Zoo Atlanta and one of the world’s reigning primate behavioral scientists, says he sees in Debbie qualities that should inspire humans.
“I don’t know of any (other) gorilla in the world that has this (Debbie’s stepparenting) kind of a record,” says Maple. “In a world where so many children are neglected and abandoned, she sets an example for all primate species, even our own.
“I think any time any organism looks after another parent’s babies, that is an extraordinary expression of altruism. Isn’t that in a way an example to us . . . that she has devoted her life to raising other gorillas’ children?”
When Debbie rejoined Frank’s family with her foster gorillas last May, their move was a part of the biggest melding of gorilla groups ever attempted in a zoo. Within two days keepers introduced a group of four leaderless females and four infants into Frank’s family of himself, two females and one baby.
Gorillas do not like new routines, and when they are placed together with animals they have never met or haven’t been around for a long time, their reactions can be unpredictable and violent. Putting babies in with a silverback male leader is especially fraught with danger. When wild silverback males take over a family or recruit new females to their troop, they kill the infants not their own to get the babies’ mothers to cycle reproductively again and thus mate with them. Gorilla infanticide occurs in zoos too. Even though Frank always has been tolerant of Debbie bringing babies he did not sire into his family, keepers use extreme caution when placing them with him.
“They never let us forget that they’re gorillas,” says Lukas, “and that we don’t know them that well.”
Since the family merger, zoo visitors tend to linger to watch the antics of the five infants, ranging from 1 to 3 years old. When they all play together–which is often–they resemble a furry pile of perpetual motion, pouncing on and wrestling with one another.
Slowed down these days by an arthritic left knee, Frank is not overly demonstrative with infants, whether they are his or not. But he lets them know he accepts them by occasionally scooping one up and placing it on his broad back for a stroll around his premises.
While Debbie takes care of her two adopted infants, the three other infants are being raised by their own mothers. Two of those mothers themselves were raised by Debbie. Tabibu, another of Debbie’s foster children in the group, is pregnant for the first time by Frank. Tabibu is a young, hand-raised female so convinced in her infancy that she was human that as an adult she still most often walks bipedally.
Lenore, an ailing 36-year-old grandmother, also joined Frank’s troop in the merger but died several weeks later of an acute abdominal infection. With Lenore gone, only three of the nine founding gorillas are left: Helen, 41, Frank and Debbie. They and the rest of the “founders” were purchased in Cameroon when they were youngsters: Helen in 1960, Frank in 1964 and Debbie in 1966. At that time, Lincoln Park and a few other zoos were just beginning to integrate information coming out in behavioral studies of wild gorillas in an attempt to unlock the secrets of getting gorillas to breed in captivity. It took more than 100 years of keeping gorillas in zoos before the first captively bred baby was born in 1956 in the Columbus (Ohio) Zoo.
Lincoln Park since the 1930s has had its identity tied in with gorillas more than most zoos. For decades it enjoyed a worldwide reputation because of one gorilla, Bushman, a 550-pound giant once voted by a national panel of zoo officials as the single most spectacular zoo animal in the world. The zoo purchased Bushman in 1930, and during the Century of Progress world’s fair in Chicago in 1933-34, reporters from around the world sent home glowing reports about the gorilla, giving the zoo an international reputation.
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When Bushman died in 1951, the zoo already had another crowd pleaser in Sinbad (1948-85), also a wild-born infant who grew even larger than Bushman. But as zoos began to see in the 1950s that wild animal populations were disappearing, they realized they had to become something more than entertainment venues.
Zoos began paying serious attention to their role in educating the public, especially in using their animals to tell about the danger of extinction in the disappearing wilderness and the need for conservation. To do that, zoos also had to take the lead in captively breeding the endangered species to maintain their collections, rather than relying on buying wild gorillas from commercial collectors.
Popular as they were, Bushman and Sinbad were not animals upon which the zoo could build a breeding program. They were socially dysfunctional animals unable to live with other gorillas because of their isolated upbringings. They never were introduced to female gorillas.
In the late 1950s, Lincoln Park’s celebrated director, Marlin Perkins, and his young zoo veterinarian, Dr. Lester Fisher, decided that if Lincoln Park were going to remain famous as a place for gorillas, it would have to breed them. Field researchers just then were revealing how gorillas in nature lived in families of multiple females led by a single silverback male. Lincoln Park set out to mimic those social groupings in the zoo to stimulate proper breeding and nurturing.
To do that, Perkins and Fisher (then Fisher himself after he became the zoo’s director in 1962) went for several years to Cameroon to buy its last generation of wild-caught gorillas, the founders: Frank, Freddy, Otto, Kisoro, Mumbi, Lenore, Mary, Helen and Debbie. As they reached sexual maturity, the group members did breed. Mumbi and Kisoro produced the zoo’s first captive-bred baby in 1970. The female baby, Kumba, still at the zoo, was only the fifth captive-born gorilla in the world and eventually became a mother and grandmother herself. All of Lincoln Park’s “founders” went on to become successful breeders except for Debbie, who has mated with Frank all her adult life.
When the earliest zoo-bred babies were born, most zoos pulled the infants immediately from the mothers and hand-raised them, fearing the parents would not know how to care for them. Fisher, who retired from the zoo seven years ago, planned to pull Mumbi’s baby, Kumba, when she was born, too.
“I had a neighbor in those days, a pediatrician, Dr. Martin Hardy,” says Fisher, “who gave me the inner strength to not pull the baby right away. He thought I could go two or three days, leaving the baby to see if the mother was able to properly feed and care for it. If she couldn’t, we still could safely pull the baby after 72 hours or so. The hope was that the animals would prove to be good moms, so we could leave them to raise their own babies, which Martin thought would be best.”
When Kumba was born July 22, 1970, Fisher left her with her mother. Mumbi did a good job taking care of her at first, but after about five weeks began ignoring the baby, forcing the keepers to pull Kumba to bottle-feed and care for her.
Beginning with the second gorilla baby born at the zoo, about three-quarters of Lincoln Park’s babies have been mother-reared. They have grown up more naturally, learning the nuances of gorilla life not just from mothers, but from every family member, each of which takes turns watching over family infants. Keepers try to intrude as little as possible.
“We don’t necessarily interfere with their lives,” says Maurer. “We jump in if they’re sick, but we don’t overstep the bounds of their living space. They know they can look to us for comfort and food, but they don’t look too much for us. If there is a squabble, we let them work it out on their own. If you don’t let the silverback have his way, you upset the family dynamics. You have to let them handle stuff like that. Once it’s settled, it’s over. They don’t hold grudges.”
In the wild, gorillas have about a 40 percent infant mortality rate, due to mothers not being able to lactate, maternal abandonment or illness, accidents or injuries to the babies. Those things happen in captivity, too, but keepers have lowered infant mortality to 25 percent by intervening to bottle-feed a neglected baby or to get medical care to a sick or injured one.
Once pulled from their mothers for hand-rearing, the babies must eventually be reintroduced into gorilla society. Most zoos try to place the babies with various females in the collection, hoping a relationship is sparked that will carry the baby into the female’s family. If that does not work, they place the baby in a habitat away from adults, bring in other gorilla youngsters to play with, then hope for the best.
Placed in the same cage with other gorillas, the hand-reared babies usually cry for their human “parents” and lash out at the other animals, biting and punching them. In gorilla society, where size and social standing are paramount, such aggression from a pipsqueak newcomer can have serious repercussions. The danger is that larger animals will react by hitting and biting back with force.
“Gorillas have awfully awkward social skills,” says Lukas.
Life in even the most well-adjusted gorilla families is marked by occasional angry eruptions and physical confrontations, especially between adult females who constantly compete to rise in the pecking order that determines who is the silverback’s most favored consort. A gorilla baby coming into an established gorilla family without a caring adult animal to protect it would be at high risk.
“It’s best growing up having Mom around for a sense of being loved, comforted and protected,” says Lukas. “She teaches them what is expected of them in gorilla society and brings them into a stable family situation. It’s important for gorilla babies to grow up with the influence of a silverback male heading the family.”
Lester Fisher recalls that, in the late 1970s, when he and his staff began considering the idea of gorilla foster mothers, there was no question that they would first try Debbie in the role because of her gentleness and love of infants.
“We had Kivu, a little female born in 1978 that had been rejected by her natural mom, and we had been raising her in the zoo nursery for about a year and a half when we took her back to the ape house,” he says.
Keepers prepared a small habitat near the front of the building and brought Debbie in. One of the keepers walked into the habitat carrying baby Kivu and sat down near Debbie (a practice since banned, as keepers are forbidden to enter any enclosure with an adult ape). Debbie sat patiently, and Kivu eventually approached her to show her displeasure by jumping into Debbie’s face to bite her. Displaying what has become the hallmark of her style, gentle tolerance of infant misbehavior, Debbie remained calm and let Kivu go her own way.
“Debbie waits for the babies to come to her,” says Maurer. “She doesn’t scare them by being aggressive, like most females are in an introduction, getting on top of the kid right away, poking it, prodding it, picking it up. If the babies bite Debbie, she tolerates it. But as time goes on, she begins to teach the baby some etiquette.
“If the baby snatches a favorite piece of food from Debbie, she will grab and pin the baby to the floor. That’s pretty frightening to a kid never disciplined before by an ape. But, with Debbie, we know she won’t bite the baby, just pin it firmly to the floor, so that the next time the kid understands that stealing is a big deal.”
Through those lessons, human-reared babies learn the pecking order that is observed in gorilla family life. The silverback is on top. Usually the mother with the most recent newborn is next in line.
“One of the main things Debbie’s kids have to learn is that Debbie always is going to be there to protect them,” says Lukas. “If things get crazy in the group and the older ones are snapping at each other, the little ones need to know that they can always go to Debbie, and, like a good mom, she’ll make sure they’re safe.”
Once Kivu came to regard Debbie as her mother and her safe port in a storm, she was introduced to to each member of Frank’s family, finally meeting Frank himself, thus becoming not only a family member, but a full-fledged gorilla.
Following Kivu, Debbie took on the zoo’s next six orphans over the next 15 years, successfully bringing each of them into Frank’s family.
Almost as much as Debbie, Frank is revered by the zoo staff because of his own gentleness and acceptance of babies. While adult gorilla males generally weigh from 400 to 500 pounds, Frank is just 340 pounds. Though small, he is strong and well-proportioned, a prodigious sire of 13 babies, with a 14th one on the way. His offspring are normal in size, and his female companions show him utmost respect and appropriate obedience if he has to intercede in family disputes with a chest-thumping display.
“He’s just a true leader,” says Maurer. “He tries to let his females settle their own disputes, but if it gets out of hand, he steps between them and barks and it’s over. He has their respect. And he is very gentle with the kids. If a new youngster comes into his group and tries to bite him, Frank more than likely will just try to stay away from the kid until they’re used to each other.”
Until Tabibu’s introduction, the zoo felt the proper time to introduce human-reared infants to Debbie was from 18 months to 3 years old. Tabibu (tah-BEE-boo) was 3 when she was placed with Debbie in 1995 and hadn’t been living with gorillas since she was a few days old and keepers discovered her mother wasn’t lactating.
Tabibu bit and ignored Debbie for weeks, crying continually for human attention. After weeks of impasse, Tabibu’s weight dropped suddenly and she nearly died, saved only after surgeons at Children’s Memorial Hospital found she had been suffering from a progressive bacterial disease.
When she got well, there was no place for Tabibu to go but back with the gorillas. Hoping for the best, the keepers put her into Frank’s family. Tabibu surprised keepers by coming to regard another ailing gorilla, Mumbi, one of the founder gorillas, as her mother and protector, and she quickly melded into gorilla life.
“She is fine now, a regular gorilla,” says Maurer of Tabibu, who now, as mentioned earlier, is pregnant for the first time.
Tabibu’s experience was so emotionally painful both for the animal and the keepers that Dr. Robyn Barbiers, Lincoln Park’s veterinarian, decided they could try bringing the orphans to Debbie at a younger, less human-imprinted age. Thus, in 1997, Debbie was presented with 13-month-old Rollie, who had been pulled from her non-lactating mother. Rollie bonded with Debbie more quickly than any previous orphan.
With so young an infant, Debbie had to learn to bring the baby to keepers for bottle feedings. The baby literally had to learn the ropes, discovering how to climb the artificial vines and trees under Debbie’s watchful eye. And Rollie had to learn how to cling to Debbie in order to ride piggyback on the up-and-down climb between the public habitat and their nighttime chambers 30 feet above.
The bonding went so well, keepers decided two of Debbie’s former babies, now first-time mothers themselves, might learn from living with her and Rollie. Thus Makari and her male infant, Jelani, and Bulera and her female infant, Madini joined them. Keepers were especially hoping that Bulera, who spent more time playing than taking care of her baby, would pick up maternal behavior. “When Madini wanted to nurse and Bulera was ignoring her, Debbie would give Bulera a couple of looks. If Bulera didn’t get the message, Debbie would pick the baby up and put her on Bulera’s breast,” says Maurer.
Long before Rollie was ready to join Frank’s family, Debbie had to take on Rollie’s younger sister, Mumbali, born in December 1997 and injured a few weeks later. Mumbali joined Debbie and Rollie when she was only 9 months old. Even more quickly than her sister, Mumbali bonded with Debbie, and Rollie never showed any jealousy as Debbie’s attention became most focused on the younger infant.
“The big sister/little sister roles kicked in right away for them,” Maurer says. “When Mumbali is nervous, she just gets behind Rollie, hugs her around the waist and the two of them waddle all over the place like a little two-car train.”
Such scenes of familial devotion gladden the hearts of keepers and especially primate curator Lukas. Lincoln Park’s director, Kevin Bell, hired Lukas in part to help him and his staff strengthen the zoo’s primate research program. In the past, the zoo has allowed visiting scholars to do observational research with its great apes. Now Lukas is training keepers to do such behavioral observations for zoo-sponsored studies while also forging formal research links with area universities.
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The biggest change on the horizon for the apes is a plan to enlarge or entirely replace the Great Ape House in the next few years. Projected to cost as much as $20 million, the new facility will be the most expensive building at the zoo.
“Functionally, this is still one of the best facilities around,” says Bell, who has sent his staff to new gorilla houses in zoos elsewhere in the country to gather ideas. He seems to lean toward enlarging the present facility, continuing to use the main, circular core as the primary living space for the animals.
In preparation for major changes, the zoo has reduced the size of the collection in the ape house. It has shipped off its two orangutans to other zoos, as well as two gorilla breeding troops, and is considering phasing out its aging chimp group in favor of establishing a colony of bonobos, a subspecies of chimps Lukas says is known to be remarkably intelligent.
Lukas is especially eager to see that the gorillas are given more access to the outdoors than the building’s present, single outdoor exhibit gives them. “In the summer, I want to see them go outside daily, most of the day,” she says. “A lot of our animals here don’t seem too keen on going outside. I don’t think we’ve done it right yet with the outdoor exhibit we have.”
The indoor exhibits are the building’s greatest strengths and greatest failures, she says. Their weaknesses are found in the exhibits’ highly stylized cement, metal, rope and canvas representations of wild gorilla habitats–trees, elevated lounging areas, shallow pools of water. They work well for the animals both psychologically and physically, but they fail miserably, Lukas says, in educating zoo visitors.
“Do people walk out of the Great Ape House,” she asks, “with an appreciation of Africa’s natural habitats that gorillas reside in, or the other wild creatures that share those wild habitats with gorillas? No. It’s very important that the public see the animals in something that approximates wilderness environments so that people begin to get a sense of how they fit into the complex web of life. If they leave the building thinking gorillas are merely funny, silly things to be played with, they may not see the need to conserve them.”
With a new or revamped ape house still a few years off, Helen, Frank and Debbie, the three remaining “founders,” will be lucky to be around to see it. Helen already is one of the oldest gorillas anywhere and Frank is at the outer limits of silverback life expectancies.
Debbie is the most active of the “founders.” Though childless, when she passes from the scene, she will perhaps be more missed than any of the gorillas she knew in her lifetime, the “founders” and their offspring.
“Being a mother isn’t just introducing a baby to the world through the birth canal,” says Zoo Atlanta’s Maple. “Being a mother is loving and the art of nurturing a young child and introducing it properly to the world so that it can eventually cope with life on its own. A lot of gorillas have failed at mothering. Debbie hasn’t. Her value is tremendous, because she became a supermother.”