Gorillas in our midst

Zoos Victoria staff were heartbroken this week at the death of the much-loved matriarch Western Lowland Gorilla, Yuska. At 51, Yuska was one of the oldest known gorillas in the world.

The zoo reported her death in a post on Facebook. “She experienced significant age-related health problems over many years, including dental issues, arthritis, a partial loss of eyesight and a series of recent minor strokes or seizures. These persistent health problems led Melbourne Zoo’s keepers and vets to determine that the kindest, most humane welfare decision for Yuska was euthanasia.

“Yuska’s legacy to the conservation of the Critically Endangered Western Lowland Gorilla species is extraordinary – from becoming world-famous in 1984 when she gave birth to Mzuri through artificial insemination, to later becoming a grandmother, great-grandmother and great-great grandmother. Her passing is a huge loss for Zoos Victoria’s community and Melbourne Zoo primate keepers both past and present who have cared for Yuska over many years.”

In 2019 Cosmos Editor at Large, Elizabeth Finkel wrote in a feature for Cosmos Magazine how a close encounter with Yuska inspired her to tell the story of the zoo which transformed itself around her into a conservation organisation. 

To see more great stories like this, subscribe today and get access to our quarterly magazine in print or digital, plus access to all back issues of Cosmos magazine.

RECENTLY I held the hand of an African western lowland gorilla. The hand belonged to Yuska, the 48-year-old matriarch of Melbourne Zoo. She was undergoing a procedure in the operating theatre housed in one of four quaint, conjoined cottages, which since 1930 have served as the zoo’s hospital. 

As I enter the room, several men and women are moving purposefully around, attending to the patient, checking the flashing monitors or hovering in the background. There’s the same atmosphere of calm intensity you’d see in any operating theatre. Yuska, covered by a pale yellow blanket, rises like a mountain on the central operating table. At the far end I see her imposing head with its prominent brow ridges and flattened crown. Her open jaw is stuffed with tubing, the pink tongue lolls to her left side. Her unseeing pale brown eyes are half closed. Her very long furry arms are splayed out to the sides and each hand is warmed by a green fleecy muff.

Yuska suffers the ailments of many a middle-aged female primate. She has arthritic joints and decaying teeth, and is at risk of heart disease. But these are not the main reasons for her procedure. It’s been scheduled to replace her expired contraceptive device, which slowly releases progesterone and is known to many women by its trade name: Norplant. At 48, well past the 35-year average lifespan of a wild gorilla, Yuska still has menstrual cycles. 

But while she’s here for contraception, Yuska is getting the full service. Vet Kate Bodley takes the opportunity to explore her teeth and gums. Wielding a dental scaler and mirror, she scrapes food bits lodged between her molars and gives the teeth and gums a clean. Chronic dental infections are just as painful and debilitating for gorillas as they are for us. 

Head vet Michael Lynch has just finished replacing the Norplant device in Yuska’s mighty shaven left forearm. He invites me to touch her hand. For a moment I demur. Then gingerly I cup my fingers over the long, curled fingers of her left hand and softly stroke her black leathery palm. Lynch points out her dainty thumb, then placing his hand on hers in his expertly way, tests the creakiness of her finger joints. “She’s not too bad,” he says. Nevertheless, Yuska’s keepers say she groans when she gets up – a problem that’s been helped recently by regular high-dose capsules of paracetamol. Astonishingly, keeper Damian Lewis has taught her to swallow the slow-release pills.

On the other side of the yellow mountain, Elske Posma, an obstetrician and gynaecologist who usually treats women at Western Health, is probing Yuska’s abdomen to check the health of her uterus. Her heavy menstrual bleeds have the vets concerned about uterine cancer. A moment later, anaesthetist Sebastien Bauquier, based at U-Vet Werribee Animal Hospital, moves in from his watch on the outer circle to take hold of Yuska’s curled left hand. He strokes it roughly and I gasp, concerned he might wake her. But that’s precisely what he is trying to do: an animal about to tip out of anaesthesia will signal its arousal in the twitch of its hands. Yuska’s state needs to walk the fine line between life-threating sedation and life-threatening (for the surrounding staff) arousal. Occupational health and safety requires that a keeper, positioned just outside the room, is equipped with a rifle. Hospitalising “category one” animals – which includes lions and the pig-like peccary – has risks for all parties.

But that’s not to say things have been overly stressful for Yuska. Arguably it’s been one of her more pleasant days, beginning as it did with a nice drop of Valium in a dollop of honey, spoon-fed by her keeper at 7.30am. An hour later, she sat in her night pen and pressed her arm to the side of the cage, as requested, for the injection that would put her to sleep.

One of the final checks for Yuska is her heart. Royal Melbourne Hospital cardiologist Leanne Balding usually wields her ultrasound wand over human patients. Apart from being slightly larger and lying more horizontally in the chest, the gorilla heart is very similar to ours. Balding is probing for the sluggish muscle movements that signal heart disease – one of the major killers of captive gorillas.

My five minutes in the operating theatre is up. When I leave I am full of questions. How is it that a 48-year-old female gorilla is still having menstrual cycles? Why would gorillas, with their vegan diet, be at high risk of heart disease? And how is it possible to get a gorilla to swallow a pill? It’s something I failed to achieve with my teenage son. 

In searching out answers to my questions, I soon found myself writing a “life and times” of Yuska. And of the zoo that had reinvented itself around her – from an old-fashioned menagerie preoccupied with collections to a world-class conservation organisation fighting extinction with every means at its disposal (see Melbourne Zoo, page 64).

The beginning of Yuska’s story leads inevitably to head primate keeper Ulli Weiher. 

Weiher was just 18 when in 1969 she became one of Melbourne Zoo’s first female keepers, having just emigrated from Germany where she’d trained at Cologne Zoo. Her first impressions weren’t favourable. 

“I experienced culture shock at the backward state of the zoo. The hygiene and diets were poor; there was no enrichment; it was a stamp collection mentality with large numbers of animals crammed in small cages.”

Four years later, two-year-old Yuska and a three-year-old male, Rigo, arrived from the Netherlands. Both had been poached from the lowland forests of western equatorial Africa, their mothers presumably killed. Though Weiher had taken leave to give birth to her own son, she visited every evening to watch the gorilla toddlers being given their evening bottle. 

Eleven years on, the orphaned gorilla pair made history. Their male baby, Mzuri, born in June 1984, marked Australia’s first gorilla birth and a world first via artificial insemination. The birds and the bees didn’t work for the pair – perhaps because they’d never seen how it was done. Yuska was not only clueless about sex, she had no idea how to care for her baby. 

Weiher, who watched the birth closely, says Yuska left the newborn lying on the straw. For four hours she encouraged her to pick up the infant, to no avail. Finally Weiher took the infant to warm him in the humidicrib. Was it frightening to get between mother and baby, I ask? “No, we have a strong bond,” says Weiher. “Of course, you have to know how to read their signals.” 

Those were the days before occupational health and safety rules required keepers to stay on the other side of the bars. Weiher and another keeper, Peter Courtney, spent 18 months working in
12-hour shifts to care for the baby.

In the 1990s, while raising my own babies, I’d been mesmerised by a newspaper clipping showing Weiher proudly cradling a gorilla baby. It’s still tacked to the wall of my study, I tell her. Weiher quickly dismisses my romanticising. “People think, ‘Oh, it’s so cute to raise a baby gorilla.’ It’s the last thing you want to do. It’s so much work.”

Notwithstanding the look of motherly pride in the newspaper clipping, Weiher keeps her emotion for the gorillas she’s raised at a professional distance. It’s part of a zookeeper’s self-preservation toolkit, she acknowledges. “You have to; they get sick and they die. You can’t afford to get so emotionally attached that you have a breakdown each time.”

Still, she can’t hide her affection. “Mzuri has Yuska’s nature. Yakini [Yuska’s second son] was the same. That gene going back to Yuska, all of them have the same personality, really nice to work with.” 

Raising Mzuri involved long days of cradling, feeding and play. His toys included a plastic jungle gym, a half-metre diameter plastic tub he liked to throw around, and some enduring favourites: hessian bags filled with wool or popcorn, as well as metres and metres of paper. “They love mucking around with it,” says Weiher. “But you have to come up with new ideas.” 

Part of each day was spent in the company of Yuska, who was gentle and curious about her son but showed no inclination to hold him, until Mzuri was around two, when Yuska started carrying him on her back. “She was the sort of parent who shows interest once the baby becomes a toddler,” explains Weiher. He was gradually integrated into the group – a tense time for Weiher. “I felt a lot of pressure. The whole world was watching in case we did something wrong.” 

For a long time she hated doing media. “It took my time away from my animals. Until I got older and realised I could use the media to bring attention to the plight of gorillas.”

Western lowland gorillas are critically endangered. Their habitat ranges across the African central equatorial countries of Angola, Cameroon, Central African Republic, Equatorial Guinea, Gabon and the Republic of Congo – home to 60% of the population. It’s shocking to learn that their major existential threat is to be butchered as bush meat – typically for weddings and funerals, explains Fiona Maisels, a conservation scientist based at the University of Stirling in Scotland: “It’s by far the biggest threat to wildlife in Central Africa.” All animals are fair game. Maisels recounts how her colleagues have hiked for days in the forests of the Democratic Republic of Congo (DRC – the larger country to the east of the Republic of Congo) without hearing a single monkey or hornbill. 

The second greatest threat to gorillas is the destruction of their forest habitat for coltan mining and palm oil plantations. Illicit coltan mining also funds bloody conflicts in the DRC that place both humans and gorillas at risk. In 2021, the European Union will introduce the Conflict Minerals Regulation to ensure that member states import tantalum, as well as gold, tungsten and tin, from responsible and conflict-free sources only.

But the thing that tipped the gorilla population from “endangered” to “critically endangered” was Ebola. Gorillas share 98% of our DNA, which not only explains why they seem like big furry people but also why they are susceptible to the same diseases – everything from colds and flu to Ebola. Because of the risks, zoos and wildlife reserves try to keep people and gorillas well apart. But human-to-gorilla transmission is not the way Ebola infected gorillas in Central Africa. Most likely the initial source of the infection was bats, says Maisels. But, as in humans, once an individual is infected, their body fluids become wellsprings of the virus, which spreads through the family via touch. And, just as in humans, the mortality rate is devastating. 

In 2004, a team of researchers tracked what happened to one closely studied group in the Republic of Congo. Over four years their numbers crashed from 377 to 40.

In 2018, a comprehensive survey by Maisels and her colleagues estimated that 361,900 western lowland gorillas survive across their range, of which only about 20% live in protected areas. As their report in Science Advances put it, their major enemies are “guns, germs and [the felling of] trees”. They estimate the population is reducing by 2.7% per year, which means it will halve in 25 years and experience an 80% decline in just three generations (one generation is 22 years) – the criterion for critically endangered status.

Despite the best efforts of conservationists, Maisels and Weiher show little optimism for the plight of wild gorillas – living as they do in some of the world’s poorest and most war-torn countries. The grim reality means that today’s zoo gorilla populations are largely seen as an “ark” species to be safeguarded until their wild habitats become safe. To that end, Zoos Victoria has long been part of an international captive breeding program that aims to increase genetic diversity. And so it was that Mzuri, aged six, was sent off to Jersey Zoo in 1993. Located on an island in the English Channel, it was established by naturalist and iconic author of animal stories, Gerald Durrell.

In return for Mzuri, Melbourne Zoo got six-year-old Motaba. Mzuri fathered two infants at Jersey. Motaba was also a great success. Weiher chuckles recalling how, upon arriving in Melbourne, six-year-old Motaba grabbed and mated with matronly 35-year-old Betsy, right under the nose of the infertile silverback Buluman. Their male offspring, Buzandi, also required Weiher’s gorilla fostering talents – and it is the picture of Weiher cradling Buzandi that I have on my wall. 

The virile Motaba also fathered Yuska’s second son Yakini, born in 1999 – also hand-reared by Weiher. 

Since then, the zoo’s gorilla mothers have mostly raised their own babies, thanks to some creative thinking by zoo staff – such as enlisting human mothers to breastfeed their infants in front of expectant gorilla mums. However, the current breeding female, Kimya, learned her mothercraft skills from other gorilla mums during her early years at Sydney’s Taronga Zoo. When she gave birth to Kanzi in 2015, she was an adept mother.

But for all the moments of delight and wonder, gorilla keepers know only too well that tragedy is never far away.

In May 2017, 32-year-old Mzuri – after five years as Jersey’s dominant male – was challenged by a younger male and seriously bitten on the groin. During surgery he suffered a heart attack and died. 

Richard Johnstone-Scott, Mzuri’s keeper at Jersey Zoo for 18 years, eulogised him in a letter to the Jersey Evening Post: “Powerful and majestic, he was a great and loveable character who will be greatly missed by his keepers in Jersey, France and Australia, where he was born.” 

Mzuri’s death from a heart attack was no surprise to zoo vets. His father Rigo met the same fate in 2013. According to a 2018 review in the International Zoo Yearbook, 75% of male zoo gorillas die of heart disease. It might seem odd that gorillas, who apart from the occasional insect are largely vegans, would suffer from heart disease. But unlike us, it’s not caused by cholesterol deposits constricting their arteries. Rather, their heart muscle becomes scarred and loses elasticity – a condition called fibrosing cardiomyopathy. Just why male zoo gorillas are at such high risk is an area of active research. The Great Ape Heart Project led by Zoo Atlanta in the US has several hypotheses, including high blood pressure and dietary deficiencies. A recent study of 69 gorillas in US zoos linked the condition in males to obesity. 

That supports Melbourne Zoo’s decision several years back to stop the bananas – in fact, all fruit. Not only are the gorillas leaner, they have better teeth. Contrary to what one might imagine, fruit makes up a small portion of their natural diet, which is mostly leafy material or “browse”. They use their immense strength – a silverback is as strong as 10 men – to pull down small trees, strip the branches and stuff the leaves in their mouths. When jungle trees do bear fruit, these tend to be small, green, bitter and full of seed – nothing like your Cavendish banana. Sourcing the immense volumes of willow, poplar and other palatable browse is an immense challenge for the keepers: gorillas at the zoo need four sticks – about two kilograms – a day. Werribee Zoo is also introducing a west African plant from the ginger family, Aframomum melegueta, known to be a favourite of wild gorillas, in the hope its anti-inflammatory effects might help ward off heart disease. 

Nailing the major factor behind gorilla heart disease remains challenging, says vet Patricia Dennis at Cleveland Metroparks Zoo, author of a recent paper linking heart disease and obesity in males.  Human heart research has galloped ahead, she explains, because researchers have access to thousands of obliging subjects. Gorilla researchers are limited to zoo residents that number in the tens – and they are not quite as obliging as humans when it comes to being poked and prodded. Imagine trying to put a blood pressure cuff and stethoscope on a gorilla. But that’s exactly what Zoo Atlanta has trained gorillas to accept. They even hold still for the slithery probe of an echocardiogram. “We’d love to do that here,” says Melbourne Zoo vet Kate Bodley, “if we can find a human sonographer willing to put in the time.” 

It’s just the latest example of how training yields enormous dividends for zoo animals, which explains the extraordinary time and manpower Melbourne Zoo expends on training its animals. At least twice a day, for instance, each gorilla receives several minutes of training.

Watching keeper Damian Lewis train the silverback Otana, you can’t help being struck by the geniality of the exchange. Facing each other squatting, one bearded red-haired man, one silverback gorilla, they make a mirror image of sorts. They touch hands through the bars, then Lewis inspects each of Otana’s feet. Responding to a signal, Otana whizzes around to allow Lewis to inspect his back. For all his bulk, Otana is surprisingly fast. Each request is rewarded by a nut but there is a keenness on both sides. It’s not about barking orders but an eager conversation with warm grunts from both parties throughout. 

It’s here that I learn how Lewis trained Yuska to swallow her arthritis pills. He began by offering her a spoonful of smooth peanut butter, followed by a chaser of coconut water poured into her mouth. Then he progressed to crunchy peanut butter. After several weeks, Yuska learned to swallow a pill the same way. “She’s now just as happy to have plain water as coconut water,” says Lewis, “and sometimes she needs no water at all. It’s helped her arthritis a lot. She seems to walk more easily.” 

But undoubtedly the most valuable training advance is that gorillas accept being injected by their keepers. That frees Bodley from the bad old days, when she would have to use a rifle to dart a gorilla. “They know exactly what we’re doing and they remember us. It causes anxiety and aggression for the silverback protecting his group. That’s the last thing you want for an animal with a suspected heart condition.”

Bodley tells me that Yuska’s examination gave her a clean bill of health. Both her heart and uterus were deemed clear of disease. As to her prolonged menstrual periods, Bodley says she’s yet to encounter a great ape that stopped cycling as they aged in captivity. Is there such a thing as gorilla menopause? It’s one of many questions about gorilla health that remain for the future.

On a fresh autumn morning a couple of weeks after her procedure, I visit Yuska in the company of Weiher. It’s great to see the heroine of this story fully recovered, sitting in her quiet grandmotherly way in the night enclosure, leaning against the grating while playful four-year-old Kanzi and her mum, Kimya, rustle about. The females are separated from Otana the silverback, and I can’t help a shiver of primal terror at being caught ever so briefly by his intense black gaze. 

Weiher looks over her charges with a mixture of warmth and concern. We’d heard Kanzi shrieking moments before and she’d rushed from our interview to check them.  Most likely Kanzi had been rebuffed by her mum when she tried to nurse. It’s high time for her to be weaned. 

My interview with Weiher comes to an end. Clearly this pesky journalist is keeping her from her charges. But the parting words express pride in her 45 years at Melbourne Zoo, most of them shared with Yuska. “I’ve had the best times seeing the old style of zoo progressing to the modern day. We are on par with any zoo.”  

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