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Sex and the Single Rhino
When a species approaches extinction, it may be time to take desperate measures—like mating brother with sister.

Do you want to take over?” Paul Reinhart asked, holding out a pail of the sort usually used for mopping floors. Inside was a small buffet’s worth of fruits and vegetables: apple slices, papaya wedges, carrots, bananas. Each of the bananas had been carefully sliced in half but left unpeeled. I picked up one of the halves and held it out. Using his prehensile upper lip, Harapan shoveled it into his mouth. After two or three seconds, he looked up with an expression that, despite our many millions of years of evolutionary separation, clearly communicated to me a desire for more. This time I chose a whole carrot, which he polished off the way a human adolescent might dispatch a pretzel stick.

Harapan, a Sumatran rhinoceros that lives at the Cincinnati Zoo, is 6 years old and not quite fully grown. He’s about eight feet long, with ruddy skin and a coat of coarse, reddish fur. Over the summer he’d put on about 100 pounds, and at the time of my visit, in the fall, he weighed seven-eighths of a ton. After going through the entire contents of the pail, he was evidently still hungry. Reinhart, the zoo’s head rhino keeper, cut open a box of ficus that had been specially flown in from San Diego and held out a branch the size of a small bush. Harapan grabbed it with his lip and chomped away noisily.

Harapan’s name means “hope” in Indonesian; depending on how you look at things, this is either entirely apposite or painfully ironic. Harapan was living at the Los Angeles Zoo until this past July, when the decision was made to send him to Cincinnati to be with North America’s only other Sumatran rhino, a 9-year-old named Suci. Suci is female, so the “hope” is that when Harapan reaches sexual maturity, something that should happen in the next few months, the pair will produce a calf. The painful part is that Suci is Harapan’s sister.

The decision to try to breed Harapan and Suci is a sign of just how desperate the situation of Sumatran rhinos has become. Last spring, wildlife experts met in Singapore for what was starkly titled the Sumatran Rhino Crisis Summit. At the summit, it was announced that the number of Sumatran rhinos in the wild had dropped to a perilously low level: only about 100 animals remain. At least that many specialists had traveled to Singapore for the meeting, so most likely there were more people discussing how to save Sumatran rhinos than there were rhinos left to save.

Meanwhile, what’s true of the Sumatran rhino is, to one degree or another, true of all rhino species. The Javan rhino, which once ranged across most of Southeast Asia, is even rarer than the Sumatran, with probably fewer than 50 individuals left, all in a single Javanese reserve. The Indian rhino, the largest of the five living rhino species, which appears to be wearing a wrinkled coat, as in one of Kipling’s “Just So” stories, is down to about 3,000 individuals. A century ago in Africa, the population of black rhinos approached a million; it has since been reduced to around 5,000 animals. (Two years ago, the Western black rhino, a subspecies that lived in and around Cameroon, was officially declared extinct.)

"There were more people discussing how to save Sumatran rhinos than there were rhinos left to save.

The white rhino, also from Africa, is the only species not currently classified as threatened. It was hunted nearly to oblivion in the nineteenth century, then made an astonishing comeback in the twentieth, owing to a combination of careful protection and breeding on game farms. Now, in the twenty-first, the white rhino has come under renewed pressure from poachers, who can sell rhino horns on the black market for more than $20,000 a pound. The horn is particularly popular these days in Southeast Asia, where it is sometimes powdered and used as a party “drug.” (In fact, rhino horn is made of keratin, like your fingernails.)

Following the Sumatran Rhino Crisis Summit, officials from the Cincinnati and Los Angeles zoos decided that, given the alarmingly small number of animals left, producing a calf was so important it outweighed concerns about inbreeding. Harapan was coaxed into an extra-large crate and loaded by forklift onto a truck. A police escort accompanied him to LAX, and Reinhart flew with him in a cargo plane to Cincinnati. A few weeks later, the zoo put out a press release announcing Harapan’s arrival. The news that it was going to try to mate siblings seemed to bring the crisis home in a way that the many previous efforts to publicize the rhino’s plight had failed to do. The story was picked up in headlines around the world.

“You can talk till you’re blue in the face,” Terri Roth, vice president for conservation and science at the zoo, told me. “There are very few rhinos. The Sumatran rhino is highly endangered. Even when you tell people, There’s only a hundred of them. But when you tell people you have to breed a brother and a sister because that’s all that’s left, boy, does that get their attention. Then people are suddenly like, this is a problem.”

* * *

As it happens, Harapan and Suci are themselves products of an earlier last-ditch effort to save the Sumatran rhino, which was initiated in 1984. That year, a group of conservationists gathered, also in Singapore, to try to hammer out a plan to protect the species. Historically, the Sumatran rhino’s range extended all the way from the foothills of the Himalayas, in what is now Bhutan and northeastern India, down through Myanmar, Thailand, Cambodia, and the Malay Peninsula and throughout almost all of Sumatra and Borneo. But by the 1980s, it had been reduced to the northern tip of Borneo, some scattered reserves on Sumatra, and a few locations in Peninsular Malaysia, and it was clear that the rhino was in grave danger. Poaching and habitat loss were driving down the number of breeding adults, and those animals that remained were left in isolated forest fragments. It was decided that a captive breeding program should be started to ensure against the species’ total loss. Between 1985 and 1994, 40 animals were captured, seven of which were sent to zoos in the United States.

The program got off to a rocky start. Ten rhinos were taken into custody in Sabah, a Malaysian state on the northeastern tip of Borneo. Two of them died of injuries sustained during capture. A third died of tetanus, and none produced any offspring. In Peninsular Malaysia, 11 animals were caught. In a span of less than three weeks, five of them died from an outbreak of trypanosomiasis, a parasitic disease spread by flies.

In the United States, things didn’t go much better. The zoos were feeding the rhinos hay, but Sumatran rhinos, it turns out, can’t live on hay; they require fresh leaves and branches. By the time anyone figured this out, only three of the seven U.S. rhinos were still alive, each in a different city. In 1995 the Bronx and Los Angeles zoos sent their rhinos—both females—to Cincinnati, which had the only surviving male, a bull named Ipuh.

Terri Roth checks her data before performing an ultrasound on 9-year-old Suci.

It was right around this time that Roth arrived in the Queen City from Washington, D.C., where she’d been working with big cats at the National Zoo. It fell to her to try to salvage the captive breeding program. A decade into the effort, the rhino’s reproductive habits still remained mysterious. Sumatran rhinos are shy and solitary. They’re wary of other rhinos and so can’t be kept in the same enclosure. But unless the females and the male were brought together, obviously they couldn’t mate.

Roth has an understated sort of determination. She threw herself into the study of rhino physiology, collecting blood samples, analyzing feces, testing urine. She became adept at performing rhino ultrasounds, an exercise that involved sticking her arm deep into the rhinos’ rectums. The more she learned, the more the challenges seemed to multiply.

“It’s a very complicated species,” she told me one afternoon in her office, which is decorated with shelves full of wooden, clay, and plush rhinos. Rapunzel, the female from the Bronx Zoo, turned out to be too old to reproduce. Emi, the female from Los Angeles, seemed to be the right age but never seemed to ovulate, a puzzle that took Roth nearly a year to solve. Finally she realized that Sumatran rhinos are what’s known as induced ovulators: they need to be in close proximity to a male before they release an egg. Roth began to arrange carefully monitored “dates” between Emi and Ipuh. Very soon, Emi got pregnant. Then she lost the pregnancy. She conceived again, and the same thing happened. This pattern kept repeating, for a total of five times.

Emi got pregnant again in the spring of 2000. This time, Roth put her on liquid hormone supplements, which the rhino received in the form of progesterone-soaked slices of bread. Finally, the following year, Emi gave birth to Andalas, a male. Three years later, she gave birth to Suci, and three years after that, to Harapan. (Emi died in 2009.) Just before Andalas reached sexual maturity, he was shipped to Sumatra, to a captive breeding facility in Way Kambas National Park, which up to then had failed to produce any pregnancies. In 2012 Andalas fathered Emi’s grandson, a calf named Andatu.

The three captive-bred rhinos born in Cincinnati and the fourth in Way Kambas clearly don’t make up for the many animals that died along the way. But they are just about the only Sumatran rhinos born anywhere over the past three decades, which is why Harapan has been brought here to mate with his sister.

* * *

Very big animals are, of course, very big for a reason. At birth, Harapan weighed 86 pounds. Had he been born on Sumatra, he might have fallen victim to a tiger (though nowadays Sumatran tigers, too, are critically endangered). But probably he would have been protected by his mother, and adult rhinos have no natural predators. The same goes for other so-called megaherbivores; full-grown elephants and hippos are so large no animal dares attack them.

Such are the advantages of being oversize—what might be called the “too big to quail” strategy—that, in evolutionary terms, it would seem to be a pretty good gambit. Indeed, until what might, geologically speaking, be thought of as recent times, the earth was full of Brobdingnagian animals.

Megaherbivores take a mega-long time to give rise to a new generation.

Toward the end of the last ice age, Europe had aurochs and cave bears and woolly rhinos. (DNA analysis has shown that Sumatran rhinos are the woolly rhino’s closest living relatives.) North America’s behemoths included mastodons, mammoths, and Megalonyx jeffersonii, a ground sloth that weighed nearly a ton. South America had its own gigantic sloths, as well as Toxodon, a genus of mammal with a rhino-like body and a hippo-shaped head, and glyptodonts, relatives of armadillos that in some cases grew to be as large as a Fiat 500. Australia was home to diprotodons, a group of lumbering marsupials colloquially known as rhinoceros wombats; Thylacoleo carnifex, a tiger-size carnivore referred to as a marsupial lion; and the giant short-faced kangaroo. Even smaller islands had their own large beasts. Cyprus had a dwarf elephant and a dwarf hippopotamus. Madagascar was home to three species of pygmy hippos, a family of enormous flightless birds known as elephant birds, and several species of giant lemurs.

From NRDC: Extinction Watch

Sylvia Fallon

Sylvia Fallon

Director of the wildlife conservation proj
ect in NRDC’s lands and wildlife program

Climate change and habitat loss are driving many species to extinction. What are some of the other threats?

Well, another crisis is the burgeoning international trade in imperiled wildlife. Whether it’s reptiles and primates for pet stores, tigers for medicine, or ivory for decoration, the wildlife trade is driving species to extinction and threatening global biodiversity. Specifically, the demand for elephant ivory and rhinoceros horn is growing at an alarming rate. Many people assume that the main demand is from China and Southeast Asia, but the United States and Europe are in fact bigger traders in wildlife—both legal and illegal.

What are the consequences of losing species such as the Sumatran rhino?

Scientists have only recently begun to understand the broader ecological effects associated with the loss of some of these species from their ecosystems. They have found that “apex consumers,” which include large-bodied herbivores like the rhinoceros, can have profound effects on their habitat. Their grazing of grasslands contributes to the overall diversity of the area, and by controlling vegetation as well as affecting how the ground absorbs moisture, grazing also mediates the rate and extent of wildfires. Studies have shown that fires are bigger and more extensive in areas where populations of large herbivores like rhinos have diminished.

Are other apex consumers also at risk?

Absolutely. Top predators have been one of the most persecuted groups of animals, because of the danger they can pose to humans and because they compete with us for food. In the United States, for example, we nearly exterminated wolves before the Endangered Species Act allowed them to recover, although they still occupy only a fraction of their historic range. For similar reasons, humans have driven other predators to the point of near-extinction, such as lions in Africa, tigers in Asia, and sharks in the oceans worldwide. Because predators occupy the top of the food chain, their loss ripples throughout the food web, causing changes all the way down to plant populations and the species they support, like insects and birds. A recent study in the journal Science concludes that top predators are critical to maintaining biodiversity and the overall functioning of ecosystems. The authors called for a global initiative to conserve the world’s remaining predators.

What happened to all these oversize creatures? Scientists have been debating this question for a century and a half, and they divide into two hostile camps: the climatists and the overkillers. According to the first group, the culprit was the temperature shift that occurred at the end of the last glaciation, 18,000 years ago. According to the second, it was humans who wiped out the megafauna through hunting. One of the earliest climatists was the British geologist Charles Lyell, a mentor to Charles Darwin. Lyell attributed the megafauna’s demise to “the great modification in climate” caused by the ice age. Darwin agreed with Lyell, though only reluctantly. “I cannot feel quite easy about the glacial period and the extinction of large mammals,” he wrote in a letter to Alfred Russel Wallace, another of the nineteenth century’s great naturalists. Wallace, for his part, initially favored a climatic explanation, but later changed his mind. “Looking at the whole subject again,” he observed in his last book, The World of Life, “I am convinced that…the rapidity of the extinction of so many large Mammalia is actually due to man’s agency.” The whole thing, he said, was really “very obvious.”

The debate drags on, but the most recent research has come down decidedly on the side of overkill. A study of Australian megafauna published in 2012, for instance, found that the continent’s giant herbivores died out before any significant climate change had occurred (but, importantly, after humans arrived).

The megafauna extinction in Australia “couldn’t have been driven by climate,” Chris Johnson, an ecologist at the University of Tasmania and one of the lead authors of the study, told me on the phone from his office in Hobart. “I think we can say that categorically.”

The plight of the Sumatran rhino also supports the case for overkill, if only indirectly. As a general rule, the trade-off for being large enough to avoid predation is a low birth rate: megaherbivores take a mega-long time to give rise to a new generation. Rhinos require six or seven years to reach sexual maturity. Gestation then takes about 16 months. For elephants, the process is even more drawn out; they don’t start reproducing until their teens, and their gestation period is nearly two years.

The problem with people (as far as elephants and rhinos are concerned) is that they don’t obey the usual rules of predator-prey relations. Humans can—and routinely do—kill animals that are much larger and stronger than themselves. This alters the terms of the trade-off and turns what was a highly successful survival strategy into a loser’s game. People don’t have to wantonly slaughter rhinos, just as they didn’t have to wantonly slaughter mammoths or diprotodons, to drive them to extinction. All they have to do is depress the already low reproductive rate, and the population will decline. If the pressure is sustained, ultimately it will drop all the way to zero.

In the case of the Sumatran rhino, the population has fallen to the point that there are those who argue that all the animals left in the rainforest ought to be pulled out of it.

“In my strong opinion, the only way to save this species is to bring them into captivity and make them breed,” John Payne, executive director of the Borneo Rhino Alliance and one of the organizers of the Sumatran Rhino Crisis Summit, told me by phone from the city of Kota Kinabalu. “This is the heart of the matter. That’s controversial. There’s people saying that’s not the way to do it.”

In fact, the Malaysian government has resolved to bring all of the rhinos left on Borneo into captivity, but at this point there are probably fewer than 10 rhinos remaining there. Sumatra, where the rest of the animals live, is part of Indonesia, and the Indonesian government, by contrast, has endorsed a plan to try to preserve its rhinos in parks. The fact that the rhino’s small population is divided between two antagonistic countries may be another reason to fear for its survival, as the two nations often seem to be working at cross-purposes.

* * *

One day in Cincinnati, I arrived at what is called the rhino’s barn—really a one-story building made of cinder blocks—in time to watch Harapan’s sister, Suci, get breakfast. On an average day, Paul Reinhart told me, Suci goes through about 100 pounds of ficus. (Providing her and Harapan with browse costs the zoo about $200,000 a year.) Once the ficus leaves were gone, Suci started in on the branches. These were an inch or two thick, but she crunched through them easily, and continued on until only a few stray twigs remained.

Reinhart described Suci to me as a “good mix” of her mother, Emi, and her father, Ipuh, who died just a few months before Harapan returned. (E. O. Wilson, who once spent an evening with Emi at the zoo, described the encounter as “one of the most memorable events” of his life.)

In the Cincinnati Zoo, Harapan, a rare Sumatran rhino, waits to be mated with his sister.“Emi, if there was trouble to get into, she’d get into it,” Reinhart recalled. “Suci, she’s very playful. But she’s also more hardheaded, like her dad.”

Suci is so used to being around people that Reinhart let me hang out with her while he went off to do other chores. I stroked her hairy flanks. Sumatran rhinos have pebbled skin that makes petting them feel a bit like rubbing a tree trunk. Though I can’t say I sensed much playfulness, Suci did seem to me to be affectionate, a little like an overgrown dog. (In fact, rhinos are most closely related to horses.) At the same time, I recalled the warning of one zoo official, who had told me that if Suci suddenly decided to jerk her enormous head, she could easily break my arm. After a while, it was time for the rhino to go get weighed. Some pieces of banana were laid out in front of a pallet scale built into the floor of the next stall over. When Suci trudged over to eat the bananas, the readout from the scale was 1,507 pounds.

The Cincinnati breeding program demonstrates how seriously humans take extinction. Such is the pain caused by the loss of a single species that people are willing to perform ultrasounds with their arms deep in a rhino’s rectum, if there’s even a chance that this will help. Time and again, people have shown that they care about what Rachel Carson called the “problem of sharing our earth with other creatures,” and that they’re willing to make sacrifices on those creatures’ behalf.

But just as clearly, the breeding program shows the limits of such desperate efforts. Once a slow-to-reproduce species like the Sumatran rhino is down to its last 100 individuals, there just aren’t many options left. Terri Roth told me that she was already starting to look for a new project to turn her attention to, because “if there are no other long-term solutions, I don’t want to continue to inbreed.” It is painful to imagine a world in which the Sumatran rhino has no place. But it’s getting increasingly difficult to see what that place is.

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image of Elizabeth Kolbert
Elizabeth Kolbert is a staff writer at the New Yorker and author of Field Notes From a Catastrophe: Man, Nature, and Climate Change. Her next book, The Sixth Extinction: An Unnatural History, will be released in February 2014. MORE STORIES ➔
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I am no expert in genetics but this inbreeding sounds like a bad idea. What is the point of producing offspring with weak genes that may come out mutated? Just to have a rhino that we can point at and say it still exists? I do know that Indonesia which still has approximately 100 rhinos left will refuse to share but the Malaysian state of Sabah still has a few left, with a male and female in captivity today in their breeding program. The Cinci zoo should keep talking to the wildlife authorities in Sabah to initiate a breeding program jointly. Experts there including Dr John Payne of Borneo Rhino Alliance would have much to contribute as well.
Although many people may disagree with me, my solution to the problem of third world poaching of large endangered species is to fund governments so that they can hire armed guards who shoot poachers on sight. I don't mean only poachers who have already killed their prey, but also those who travel into wildlife preserves carrying firearms, poison, or snares. All too often, local court's sentences carry no power to stop poaching, and the numbers of some wildlife are nearing the point of no return. Why arrest people, only to have a minimal sentence, which is no deterrent to others. When the payment for poaching is worth several years of a normal salary, some are tempted to poach. Make the thought of death be a deterrent, as nothing else may be. I read that this approach was the final solution that worked in one part of Africa. I've seen rhinoceros in the wild in a large Nepal wildlife preserve, and I saw nothing to deter poachers there. These animals will, at some point, become targets. I'm sorry, but I feel that a poacher's life is NOT more valuable than an entire species. I'm a retired BLM/NPS law enforcement ranger, who has traveled in 20+ third world countries since retirement. My job in the U.S. involved poaching arrests, but none of these were for threatened species, and U.S. Federal judges usually gave adequately severe sentences to deter others.