Outside of China, only six pandas have given birth. If Bai Yun, the female panda at the San Diego Zoo, joins their ranks, her fragile, hairless, four-ounce baby will face a number of threats to its existence.
If, however, the infant survives and thrives and grows the trademark black-and-white coat, its cuteness soon will outstrip even the formidable cuteness of the two adult pandas in Balboa Park. The cub will be the property of the People’s Republic of China, and the deadline for its repatriation (18 months after its birth) by then will be fast approaching. Huge lines will materialize, as well as innumerable headlines and national TV spots. And here’s one more prediction: if those heady days come, the average citizen won’t remember that when the zoo asked the U.S. government for permission to bring pandas to San Diego to breed them, the government turned the zoo down.
That happened in 1993. The zoo only later succeeded at getting the pandas here by reworking its request and vowing to undertake broad-based scientific research on the pandas. Nowhere did the zoo promise not to try for a birth as part of that research, and when the U.S. Department of the Interior finally granted the permit in 1995, it nowhere forbade such an attempt.
So if Bai Yun has a baby, the zoo won’t get into trouble. Indeed, amidst the happy hullabaloo, uninformed observers may assume that the panda research led to the panda baby and that the political hoop jumping was insignificant prelude. The truth, however, is closer to this: large-scale political forces led to the birth of the San Diego Zoo’s extraordinary panda-research program.
As with all politics, the political forces that thrust the San Diego Zoo to the pinnacle of Western panda research have sprung out of the ground of history. That history is remarkably short, considering the animals’ popularity. “One of the strangest aspects of the panda’s success is that it lacks the traditional background of ancient mythology and legend so typical of the other great animal stars,” write the behaviorists Desmond and Ramona Morris in their 1966 book Men and Pandas. Although Chinese records mention the panda’s existence more than 1300 years ago, the Morrises conclude that giant pandas made little if any impression upon Chinese artists, storytellers, or medicinal healers in the more civilized parts of China, remaining “virtually unknown” until at least the 19th Century. Outside China, no one knew the black-and-white bears existed until the famous French Lazarist missionary Père Armand David collected four dead specimens in 1869 and sent them to the Museum of Natural History in Paris. Two other European museums acquired a few panda parts, but awareness of the animal remained low until Western adventurers began competing to shoot one.
Theodore and Kermit Roosevelt, sons of Teddy, won first place in that informal contest in 1929, together slaughtering a sleepy old male whom they scared out of the hollow of a giant spruce tree in a region of China that is now part of Szechwan. The dead panda’s stuffed and mounted carcass wound up in the Field Museum in Chicago, where it aroused the envy of other Western natural history museums. Several sought their own specimens, and though (Chinese hunters supplied some of the demand, by 1935 only four other Westerners had managed to kill a panda. By then, an even more exotic competition was heating up: the one to capture the first live panda and bring it to the West.
Two ambitious American animal collectors were vying for this honor in 1936 when one of them got sick in Shanghai and died. In a bizarre turn of events, this man’s widow, an attractive New York dress designer named Ruth Harkness, thereupon decided to travel to China to carry out her late husband’s quest. Led by a Chinese-American game hunter and aided by a tremendous string of good fortune, Harkness survived the grueling 1800-mile journey into the Chinese panda country. There her luck continued to hold, and on a wet morning on November 9,1936, she laid her hands on a baby panda weighing less than three pounds. Some of the local hunters aiding Harkness had inadvertently chased off the mother.
The baby was thought to be a female, no more than ten days old. But few people knew much about panda genitalia in those days (the animal was male, a postmortem exam 17 months later was to reveal). And no one had ever seen a newborn panda. Harkness’s specimen, which in fact was probably at least a month old, had outgrown the early stage of looking like a hairless rodent and blossomed into full-blown baby-panda cuteness. This had powerful consequences when Harkness arrived in San Francisco with the captured cub. Reporters and photographers mobbed her, then sent their breathless prose and photos around the world. In New York, Harkness received a visit from the Roosevelt brothers, and as Theodore dandled the cub in his arms, he declared that he would just as soon shoot and stuff his own son as he would the panda baby. Fellow trophy hunters seemed to agree, but the public fascination with pandas triggered a race among zoos worldwide to acquire the animals for their collections.
The young San Diego Zoo stayed clear of the initial fray. A full ten years passed before the zoo’s director. Belle Benchley, revealed that she was working through the U.S. State Department to obtain two pandas in exchange for fellowships at West Coast universities. But political upheaval in China sabotaged Benchley’s overtures, and by 1958 director Charles Schroeder was declaring that the San Diego Zoo couldn’t afford the going price for pandas ($25,000 per head, by one report). By then every one of the 14 pandas that had made it to the West in the Great Panda Rush of the ’30s and ’40s had died, most soon after arriving in their respective cages and enclosures.
Tensions between China and America had also built, a situation that persisted until President Richard Nixon’s 1972 trip to Beijing. After that diplomatic foray, the Chinese government presented the National Zoo in Washington, D.C., with the panda pair Ling Ling and Hsing Hsing. Another consequence of Nixon’s trip was that more Americans began venturing into China, and one of them was Clayton Swanson, then the San Diego Zoo’s general manager.
Now retired and living in Denver, Swanson says the warm and extensive relationship that exists between the zoo and numerous Chinese zoologists and government officials began by chance, when Swanson, traveling in Australia in 1978, met a young veterinarian from Hong Kong’s Ocean Park Aquarium. The two got to talking about the possibility of their respective institutions exchanging animals with China and each other. They stayed in touch, and in 1979 Swanson received an invitation to the Forbidden Kingdom.
In December of that year, he visited Guangzhou, Hangzhou, Shanghai, and Beijing. Along the way, he suggested animals that the San Diego Zoo might lend or give to the Chinese institutions, and he produced a list of animals coveted in San Diego, including giant pandas. He was told that these were reserved as gifts of state. But Swanson found the Chinese open to the idea of animal exchanges, and over the next five years he journeyed to China at least a dozen more times. As a result of his negotiations, the San Diego Zoo eventually could boast that it possessed the greatest collection of Chinese animals outside of China. When Swanson retired in 1984, the collection still didn’t include giant pandas, but the San Diego Zoo was in a perfect position to respond to the fundamental shift in global panda politics that came a few years later.
In 1984 the Chinese government announced it would loan two pandas to the Los Angeles Zoo in conjunction with the Olympic Games. The Chinese had never loaned pandas before. Pandas had been plundered by foreigners, then used as diplomatic tools. Although the L.A. loan might have been seen as a variation upon the latter theme, it came with a twist. After their stay in Los Angeles, the animals were to be shipped to San Francisco for three months — in exchange for a substantial rental fee. This arrangement touched off a scramble by zoos for pandas that to many observers recalled the rough-and-tumble competition that had occurred 50 years earlier.
Among the victors this time was the San Diego Zoo, which in May of 1987 announced that it had negotiated a deal to display two pandas for 200 days. The zoo hurried to transform a clouded leopard enclosure into a space for the black-and-white stars, and on July 23 they arrived.
Today it’s almost hard to recall the intensity of the reaction to their public debut. Some 800 major zoo donors and assorted public officials were ushered in early to ogle the animals (Basi and Yuan Yuan). Meanwhile, lines outside the admission gates built to four times their normal length. Calls jammed the special panda phone lines set up by the zoo to advise visitors about the best viewing times and parking alternatives. And the fervent response didn’t abate much as the animals’ stay wore on. As the departure approached, zoo officials announced that some 2.2 million people had come through the gates during the pandas’ stay — nearly half a million more than the normal number for a comparable interval.
Three days before the end of the loan, the zoo’s executive director, Douglas Myers, was quoted in the San Diego Union saying, “Every place I go in town...everybody is going through a mourning period now because they’re leaving.... This is the most wonderful thing that ever happened to the San Diego Zoo.” It had come at a price. In addition to the costs of remodeling the enclosure and incurring extra panda-related labor and expenses, the zoo had paid the Chinese $400,000 for the privilege of borrowing the animals. But when the zoo released its 1987 annual report, it showed that the increased attendance and extra sales of food, drinks, and panda paraphernalia had brought in a whopping $4.4 million more than the zoo had spent.
Elsewhere, other zoos were also reveling in their borrowed pandas’ phenomenal drawing power, and by 1988 no fewer than 30 institutions were dickering with the Chinese to get in on the action. By that point, however, powerful observers had become dismayed by the broader consequences of the panda loans. One of the most commanding and articulate of these was George Schaller, the New York Zoological Society biologist who had conducted the first major study of pandas in the wild. At first, Schaller had favored a “strictly regulated” panda-loan program. “But I changed my mind,” he wrote in his 1993 book The Last Panda, “after observing the greed, politics, lack of cooperation, and undisciplined scramble for pandas that characterized the whole loan program.”
The American Association of Zoological Parks and Aquariums (AAZPA) had developed guidelines to ensure that the panda loans would not hurt the species. One of the most obvious ones was that only sterile animals or those past breeding age should make the journey to America from China. Yet the Chinese instead “sent whatever pandas were readily available,” Schaller writes in his chapter about the “rent-a-panda” program. American politicians goaded them on. “Such public figures as Nancy Reagan, jimmy Carter, and George Bush became involved in the transactions,” Schaller writes. Another relentless lobbyist was New York mayor Ed Koch, even though (according to Schaller) “the Bronx Zoo...felt that China should first develop an effective captive breeding program before sending the precious animals on tour.” But political pressure won out, and the Chinese sent the New York Zoological Society an adult female that had been caught in the wild and supposedly could not breed. “Shortly after arrival she came in heat,” Schaller records. “The male sent with her was too young to breed”—and so much smaller than the female that the two were separated, lest she hurt him.
The New York loan was “an embarrassment,” in Schaller’s words. And other breedable animals made their way to America. Basi, the San Diego Zoo’s darling visitor, was seven years old. Beyond this, the panda-loan program also generated questions about just what was happening with the money funneled back to China. Two separate Chinese organizations regulate — and were then renting — pandas: the Ministry of Forestry and the Ministry of Urban and Rural Construction and Environmental Protection. Cooperation between the two was rare. Meanwhile, the animals generating all the bucks for both were being made to juggle balls, ride bicycles, and perform other circus tricks. “Something had gone awry,” wrote Schaller. “The 1930s were back in a different guise.”
This time a backlash developed fast. Less than five months after Basi and Yuan Yuan left San Diego, the U.S. Fish and Wildlife Service, responding to a lawsuit filed by the U.S. arm of the World Wildlife Fund and the AAZPA, suspended the issuance of panda-import licenses. Three months later the door on the other side of the Pacific also closed, as the two Chinese ministries overseeing pandas put their rivalries aside long enough to announce that they were suspending panda loans to America.
When Basi and Yuan Yuan left here, at least one of the San Diego Zoo trustees had expressed the hope that pandas would soon be back. But as the ’90s began, the chances of that happening looked bleak. Although the Fish and Wildlife Service started issuing permits again in 1991, the AAZPA declared a year later that any zoo obtaining a short-term loan of pandas would be suspended from the important professional organization. Myers, the San Diego Zoo's director, says it was thus a “wonderful surprise” when he learned sometime in 1991 that the Chinese Ministry of Forestry might be interested in granting a long-term loan. “No panda had been outside of China for more than six months,” Myers says today. The ability to keep a breeding pair for substantially longer than that — say for three years—might dispel the stinky residue of the “rent-a-panda” era. A zoo could time the animals' travel so as not to disturb their reproductive cycles, then turn the full force of American technology upon the challenge of getting them to breed.
Myers says around the end of 1991 he told the zoo’s board of trustees that a long-term loan looked like a possibility, and the board encouraged him to pursue it. Given the hot-blooded race among zoos for pandas in the past, it’s easy to imagine Myers and the board members rubbing their hands at the thought of beating their competitors to the furry gold mine. But Myers paints a different picture of the atmosphere within the zoo’s administrative building. He says he always envisioned that long-term loans would be made to several zoos around America, so he invited five or six directors of likely panda recipients to come here and meet with him about developing a national panda policy. He says this meeting led to a larger AAZPA-sponsored gathering in Washington, D.C., of panda experts from around the world. They came up with the idea of forming a Giant Panda Conservation Action Group composed of about 25 member zoos. Myers says not all of these organizations were seeking pandas, but all agreed to contribute funds to support panda research. The group sent its first $ 100,000 to the Chinese Ministry of Forestry to enable it to buy scientific equipment. But Myers says the gift also was “to illustrate to our government that we were serious about working with giant pandas and that the Chinese were serious about using the money we sent to them to help giant pandas.”
By the middle of 1993, convincing Washington bureaucrats of the San Diego Zoo’s good intentions had become a top priority for Myers. In September of 1992, the zoo had signed a tentative agreement with the Chinese to arrange the long-term breeding loan. But because giant pandas are a federally protected endangered species, the zoo needed a permit from the U.S. Fish and Wildlife Service to bring them into this country. And by the summer of 1993, its chances of getting a permit weren’t looking good. For one thing, the World Wildlife Fund had urged the U.S. government to reject the San Diegans’ request.
The conservation organization had criticized the choice of the two specific animals San Diego was seeking. Both were born in the wild, and even though the zoo claimed that both had been rescued after being injured and could not be released, the World Wildlife Fund argued that only captive-born animals should be loaned in order to minimize the incentive to capture more wild pandas. The World Wildlife Fund also complained that the zoo had refused to set up an accounting system to track the money it would make off the pandas’ presence. And it criticized the zoo for charging ahead in its pursuit of a loan before an international breeding program had been organized.
At about the same time. Interior Secretary Bruce Babbitt, who had read George Schaller’s newly released Last Panda, sent the zoo a grim letter warning that he was concerned China might not be doing enough to conserve wild pandas. The official bad news came in September from Kenneth Stansell, deputy chief of the Fish and Wildlife Office of Management Authority. Although Stansell conceded that Shi Shi, the male panda sought by the zoo, had been legitimately rescued from the wild, he questioned the circumstances surrounding the capture of the female, and he stated that she didn’t appear to be a good breeding prospect. Stansell’s rejection letter raised other concerns too, and it concluded that the agency could not grant the permit because a convincing case had not been made that a long-term loan of pandas to the San Diego Zoo would benefit the panda species.
As discouraging as the news must have been, Myers says he and the trustees never considered giving up. For one thing, the zoo had already put a lot of money on the table. It had spent about a million dollars to build panda facilities, and it had run up costs writing the permit, sending zoo employees to China, and so on. Myers furthermore had sounded an apocalyptic note at the news of the permit rejection, telling the San Diego Union that “if this derision sticks, truly the panda does not have a chance.”
So the zoo resolved to appeal, an unprecedented move. Today Myers, a polished man who exudes self-assurance, uses props when he recounts the permit-seeking process. First he reaches behind his imposing desk and grabs a thick binder. It represents the zoo’s original application, he says. When zoo officials heard that trouble was brewing, they tried to forestall it by answering more questions. Myers places another binder on the pile. When the zoo reapplied after being turned down, that generated several more bulging binders, which he adds to the growing column. Then Fish and Wildlife asked for an executive summary—one more thunk in Myers’s exasperated monologue. The Final tower consists of well over 8000 pages. “Bruce Babbitt told me that’s the largest permit application they’ve ever received,” Myers says with something like satisfaction.
Among those pages was more than mere empty verbiage. Two years before the U.S. government turned down the San Diego Zoo, a baby panda had been born at the Chinese Ministry of Forestry’s breeding center in the Wolong Nature Reserve, the first ever to be born and survive there. In the wake of the rejection, the Chinese agreed to substitute this animal, a female named Bai Yun, for the female with the questionable origins.
To deflect criticism that it would make money off the pandas, the zoo promised to provide the federal government with a detailed annual report about its panda-related income and expenses, which would include a $1 million annual payment to the Ministry of Forestry. (This money was earmarked for increasing the size and number of panda reserves.) If the income exceeded the expenses, the zoo pledged to spend the panda profits on conservation projects.
Still there remained a more fundamental question: whether importing pandas to breed them in captivity benefits the panda species. In the feds’ rejection of the zoo’s permit application, one could read a negative answer to that question. Don Lindburg, the animal behavkmst who heads the San Diego Zoo’s panda-research program, suggests that one reason for this is that Western zoos in the past have claimed to be trying to breed pandas. They’ve often made a lot of money. But they’ve produced few panda babies.
Lindburg adds that over the past 20 years there’s been a change of consciousness among conservationists. More and more have come to believe that if people concentrate just on breeding animals in captivity, they may lose the opportunity to save wild habitats — and the animals that are left in them. This view suggests that to save a species, you need to know much more about it than how to bring sperm and eggs together and ensure that the resulting embryos make it through gestation. You need to understand their natural behavior, and you need to study the mechanisms that allow them to survive and thrive in the wild. In short, you need to do a whole bunch of scientific research of the sort that the San Diego Zoo has distinguished itself at doing. The zoo thus argued in its revised permit application, filed in July of 1994, that it should be allowed to import Shi Shi and Bai Yun to use them as the subjects for such research.
Five months later, Myers was grinning and shaking hands with Interior Secretary Bruce Babbitt, who made a special trip to San Diego to sign the import permit. “I know you were a little bit put off when I rejected that (first) application,” Babbitt declared. But the rejection had led to a reworked application that is “just absolutely magnificent.. .. It’s quite dear now that [the San Diego Zoo’s] research will focus on preserving the species in the wild.” The cabinet member announced that “several weeks before” he had come to San Diego incognito and headed to the zoo. “I arrived here one morning, laid down my SI3 entry fee, and spent two and a half wonderful hours. I had a really in-depth look to confirm what I already knew — that this zoo is one of the world’s great conservation and research organizations.”
Some observers don’t believe that Babbitt changed his mind about granting the permit either as a result of that undercover visit or after reading the 8000 pages of application arguments. Mark Berman, a program associate for the San Francisco-based Earth Island conservation organization, declares that Babbitt was pressured to reverse his earlier rejection of the permit by President Bill Clinton. “Clinton paid a visit to San Diego during one of his campaign swings, and he was approached by the board members of the San Diego Zoo who are part of the Democratic Party,” Berman says. “They got to Clinton and had Clinton reverse Babbitt’s decision.”
Berman, however, offers no evidence to support this contention, and the president of the zoo’s board of trustees, Dr. Kurt Benirschke, says, “I don’t remember that at all.”
With the permit in hand, an ebullient Myers declared that the pandas should be arriving in San Diego by mid- to late spring. The zoo director adds, “We dropped ‘mid- to late spring’ real fast and started saying ‘soon.’ ”
For even though the Chinese had agreed more than two years before to loan the pandas to San Diego, a Chinese export permit still had to be signed by the two competing Chinese panda-management ministries. And with the zoo’s annual $1 million payment almost in hand, the two ministries began haggling over which would control the money. They finally worked out a deal, but then the permit had to go to the Chinese “State Counsel” for approval, and every hiccup in the diplomatic relations between America and China seemed to choke the progress toward this final step. “First there were intellectual-property concerns,” Myers recalls. “Then we had some warships in the Straits of China.” The U.S. government granted the Taiwanese president a visa to attend his class reunion at Cornell University — and once more the elaborate panda arrangements threatened to collapse.
When more than a year had gone by and still no permit had materialized, the zoo enlisted the aid of U.S. Senator Dianne Feinstein, a friend of Chinese president Jiang Zemin since their days as respective mayors of the sister cities San Francisco and Shanghai. Feinstein pressed the Issue in a meeting with Jiang and followed up with a written appeal. By June of 1996, grim noises were beginning to issue from Balboa Park, as the zoo calculated that the tab for its thus-far-fruitless panda quest had reached the $2.5 million mark. Feinstein wrote Jiang again, warning that the zoo might opt “to put its energies into other areas which have not been given the attention they deserve because so much of the society’s efforts have been directed to the panda project.” Bill Fox, then-president of the zoological society board of trustees, on June 25 asked the board of trustees to give the Chinese a deadline. Though the board refrained from doing so, the Chinese appear to have sensed the board’s edginess because on June 27, word came that Beijing had finally dispensed the necessary approval.
Less than three months later, Bai Yun and Shi Shi arrived at the zoo’s gates, and after a seven-week quarantine, they made their first public appearance. “For this zoo, today is the Super Bowl, World Series, and Academy Awards rolled into one,” a beaming Bill Fox told one reporter. “We are the envy of every zoo in the world.” Despite the long lines of visitors. Fox pointed out that the pandas were not really on exhibit. “This is a research station,” he declared, one in which the reproduction, habitat, nutrition, and genetics of the giant panda would be thoroughly investigated.
Today there are still those who argue that pandas didn’t have to be flown to San Diego to achieve that objective. The San Diego Zoo “could have virtual reality and video of pandas in an exhibit in San Diego without having the live animals,” suggests Berman of Earth Island. “Why did they have to build this exhibit that cost several million dollars? They could have funneled all that money directly into panda conservation in China.... They should be pouring the money into habitat restoration and protecting (pandas) from poaching. Into educating the native people in China about how rare and important this species is to preserve. Or sending over the equipment…where it’s most needed to study the animals that are left.”
Berman charges that the zoo in reality wanted the pandas in San Diego because “it’s publicity. Increased gate receipts. They’re the only zoo in the U.S. to have a pair of pandas at this moment. And zoos on average have to have something new year after year to get people to come back.”
Richard Farinato, director of the Captive Wildlife Protection Program of the Humane Society of the United States, echoes Berman’s statements, if in a less strident tone. “I don’t begrudge the fact that pandas are a draw,” he says. “But if we’re going to save pandas, it’s not going to be because we do research on their olfactory sense in zoos. It’s going to be because land is set aside, corridors are created, logging and poaching is stopped — and all of that has to occur in the country of origin.” Even though the San Diego Zoo’s research is “probably valuable,” he concedes, “I would question at the same time: why is it necessary to bring two animals halfway around the world and set them up in San Diego when the research could be done in China?”
Don Lindburg responds by pointing out that pandas in San Diego can generate a lot of money that can be used to preserve the wild population. And the zoo’s Center for Reproduction of Endangered Species (CRES) also has had the opportunity to develop “new technologies that could be exported to China.” Housed in the old zoo hospital not far from the Old Globe Theatre, the zoo’s research arm has grown since 1975 into one of the top such centers in the world, with an annual budget of more than $4 million and a staff of 35, including 15 senior scientists. None of them has been studying giant pandas exclusively, but most have been working with Bai Yun and Shi Shi.
Communication and transportation breakthroughs that have shrunk the distance between many places around the world haven’t yet had much impact on the remote reaches of Szechwan, where the Ministry of Forestry’s Wolong panda-breeding facility is located. The phone there receives only incoming calls and often doesn’t work at all. The trip from San Diego to the reserve requires almost 24 hours of travel, and conditions at the reserve are primitive. Nonetheless, the zoo has sent several of the CRES scientists to China at least once. None has spent more time there than Ron Swaisgood.
Swaisgood got his Ph.D. from UC Davis in 1994 after studying the predator-prey relationship between rattlesnakes and ground squirrels. Then one day an ad in Science magazine caught his eye. “Actually, it didn’t mention pandas,” he recalls today. It stated only that the San Diego Zoo was looking for an animal behaviorist willing to live in Third World countries for up to six months every year to work with “solitary mammals.” After talking to Lindburg, Swaisgood decided that the job “was a wonderful opportunity.” The fact that his principal study subject would be pandas “was an interesting change,” he comments. “I went from studying some of the most hated species in the world — rattlesnakes and ground squirrels—to the world’s favorite, the panda.” He adds that he’s enjoyed them all. “I like working with animals, period.”
Swaisgood joined the zoo as a post-doctoral researcher in May of 1995, and the following March he made his first trip to Wolong. The Chinese who manage the reserve started enjoying significant success at breeding pandas in the early ’90s, and today about 30 of the animals fill the austere enclosures there. In the three months of his first visit, Swaisgood concentrated on one of the mainstays of the field of animal behavior, simply watching the animals and recording what they do. Although Western zoology has recognized this as a valuable activity for decades, animal behavior is still a new science in China, Swaisgood says. “The first Ph.D was given in 1991.”
Don Lindburg had first observed pandas in China in 1994 and had worked with a system of symbols for recording specific panda behaviors developed at the National Zoo.
Swaisgood took this “ethogram” with him to Wolong and refined it. When Bai Yun and Shi Shi arrived in San Diego in the fall of 1996, he had already set up a panda-observation program. “The second they got off the truck, we started watching,” he says.
Today, some ten volunteer observers and three paid research assistants share the panda-observation tasks. “Many of the volunteers are students who are thinking about making a career in this area and want to get some hands-on experience,” Swaisgood explains. Each makes a significant commitment to the observational research. During the nonbreeding period, the pandas are observed twice a day (from 8:00 to 10:00 a.m. and again in the afternoon from 1:00 to 3:00) five days a week. During the spring, in the weeks leading up to the female’s annual ovulation (the only time all year when she’s receptive to having sex), the observation period can be extended to around-the-clock. Swaisgood says the volunteers have to work in the program for at least six months because it takes them two or three months to get proficient.
During their assigned time, they show up at the panda quarters and, holding a clipboard, station themselves within viewing distance of one of the two animals. A device on the clipboard beeps once a minute, and each time it does, the volunteer writes down a letter or a number from the ethogram that indicates what the panda is doing. Swaisgood says the ethogram has grown to include about 70 behaviors, each quite specific.
There are three symbols for playing, for example: one for water play, another for playing with an object, and a third for somersaults and other “locomotor play.” Pandas have scent glands that they rub on various objects in their environment in one of four basic ways, and each of these has its own notational symbol. In the handstand position, for example, the male panda will stand on his hands and rub his elevated hind end against a tree or other object. One explanation for this strange action, offers Swaisgood, “is that the higher the source of the scent, the further it will carry. So it may maximize the chance that other pandas will actually smell and find the scent.”
Hardest of all for new volunteers is to distinguish the noises the pandas make. Those sounds “are really pretty remarkable,” Swaisgood says. “They’ve got about a dozen pure vocalizations, but in addition to that, all those grade into each other, so there’s an enormous complexity to it.... There’s probably a dozen times a dozen variations that they can use.” In the breeding season, both males and females bleat in a way that “almost sounds like a goat,” Swaisgood says. Females in their peak of their heat also chirp like a bird. “It’s a type of sexual advertisement, and it means she’s very receptive.”
In addition to noting what the two pandas are doing, volunteers record where they are and how close (in terms of body lengths) they are from each other. When Swaisgood and his helpers have analyzed the data, they’ve found that the pandas have spent “99 percent of their time greater than three body lengths apart.” This is partly by design. Pandas in the wild live most of their lives alone, coming together only in the spring to mate. So for Shi Shi and Bai Yun, the San Diego Zoo created separate sleeping quarters and separate exhibit areas (where the public can view them). The pandas also have a huge private backyard filled with trees and plants, but it’s divided in two by a walkway built to accommodate the panda observers. Much of the time Shi Shi is kept on one side and Bai Yun on the other. Only in the spring do the keepers start leaving the door between the two open.
"What we’re trying to do is find a balance,” Swaisgood explained one misty morning in February. “You don’t just want to introduce them cold turkey...because they can fight. But also we don’t want them to spend too much time together, because with pandas we think that familiarity may breed contempt.”
This particular day was only the third time in 1998 that the door connecting the two backyard areas had been left open. On the First occasion, Swaisgood said, the female panda had stayed up in her favorite tree, deep asleep for the entire observation session. On the second occasion, she entered Shi Shi’s territory and came to within about ten feet of him. “Then he approached closer to her, and he moaned a little bit.” A panda moan, according to Swaisgood, can signify “both attraction and repulsion at the same time. It’s a little bit more ambiguous than a growl.” After the moan, both animals drifted apart.
This day, each one at first stayed on its own side and settled down to eating — a top panda priority. In the wild, where 99 percent of their diet consists of bamboo leaves and stems, pandas spend 14 hours a day at this task. “They’re related to bears, and they still retain the digestive tract of a carnivore,” Swaisgood said. To compensate for the fact that ursine digestive tracts aren’t adapted to eating plants, the pandas “have to consume huge quantities of bamboo to survive.... They have to eat around the dock, night and day.” Swaisgood noted that they also defecate about 48 times a day.
In captivity, “Lots of pandas give up bamboo entirely and just eat bread and milk,” he continues. In fact, they gobble that up with gusto. “But we [humans] like ice cream best. And if we didn’t act rationally, we would eat ice cream all the time.” Swaisgood said pandas subsisting on bread and milk have fared about as well as humans who eat ice cream exclusively. “Digestive disorders have been the number-one cause of death in juvenile pandas in captivity. And probably that’s because the diet is not high enough in fiber. It’s too rich.”
Mindful of this, the San Diego Zoo’s nutritionist formulated special high-fiber panda biscuits loaded with protein, vitamins, and other nutrients. “See how he’s searching right now?” Swaisgood said, pointing to Shi Shi. “He’s smelling the ground and he’s looking around. There are biscuits hidden, so it’s like an Easter egg hunt.” Every so often, the male rocked back into a sitting position, his long pink tongue flicking in and out — a sign that he had located one of the goodies. “We think this is a much better way of feeding him than just giving him a bowl of food,” Swaisgood said. “They’ll wolf that down and then go sleep it off.” Searching for the biscuits, in contrast “keeps them active longer and encourages them to explore their environment.”
Shi Shi eventually made his way to what looked like a stand of bamboo but in fact was fresh-cut bamboo stalks held in hidden metal clamps. “We’re presenting it in a way that mimics the natural feeding,” Swaisgood explained. This too “makes them have to work a little bit more for their food. They have to break it off in the same manner they would if they were getting bamboo in the wild.” For a long moment, Swaisgood watched the male panda strip small bunches of leaves off the bamboo stems with a paw, then, in one swift motion, compress them into a plug the size of a fat cigar. The male panda then bit off a chunk of the compact material. A bone in the panda wrist has evolved to function like a thumb, Swaisgood pointed out, enabling this efficient style of eating. “I always say that watching a panda cat bamboo reminds me of watching a Frenchman eat fruit,” the young scientist remarked.
As graceful as the performance was, it made for tedious note-taking, only slightly more interesting than if the animals had been sleeping. Those two activities make up 98 percent of the pandas’ time, according to Swaisgood. But what goes on the rest of the time they spend the panda-observers into a note-taking frenzy, as Bai Yun demonstrated on this morning.
After munching on bamboo and biscuits in her enclosure, the six-and-a-half-year-old female ambled through the portal leading to the male’s side, then, swinging her head in the distinctive manner of her kind, she made an easygoing circuit that brought her to Shi Shi’s vicinity several minutes later. As she drew close, the male emitted a low, guttural sound that Swaisgood declared to be a moan. This was followed by another mildly threatening noise, then some startling, doglike barks delivered while charging at the female. Then the male growled, chomped, growled again, barked again, and honked. “The honk is frustration usually,” Swaisgood commented. “He wants her to leave and he’s frustrated because she won’t.”
Bai Yun in fact was edging away, heading back to her own enclosure. She had tried not to be pushy, Swaisgood observed. “She rarely looked at him, and that’s intentional. A direct stare in pandas is a threat, as it is with a lot of animals. And actually people think that one of the functions of the black patches around (pandas’] eyes is to accentuate that threat. When they put their head down and their ears up, it almost looks like two big sets of eyes.” Conversely, “When they’re trying to submit, they do the opposite. They look away and they’ll actually cover their eyes with their paws. It’s a sort of an appeasement gesture.” Swaisgood expressed the opinion that Bai Yun was acting as if she wanted to interact. “And I think she’s also learned that Shi Shi is not disposed to social interaction.” A dental examination this spring determined the male to he between 19 and 21 years old — at, if not beyond, the reproductive limit of pandas in the wild. During Bai Yun’s 1997 breeding season, Shi Shi had acted like a crotchety old geezer lacking any interest in sex. On this morning, Bai Yun “was maybe probing to see if he’s changed since last year,” Swaisgood theorized. “And she didn’t push the issue too much, though she didn’t run off immediately."
In the months that followed, the CRES scientists and the panda keepers had reason to hope that Shi Shi might have changed. He seemed more active and playful and less fixated on food. He did more scent marking, including two of the acrobatic upside-down variety. But when Bai Yun reached the peak of her sexual receptivity this past April 8, Shi Shi fended off her advances with a battery of growls barks, and charges.
Swaisgood missed all this action. “If you want to learn about pandas you can’t just stay at home and study two pandas. In Wolong, there are ten females that will come,” he said just days before departing for another two-and-a-half-month stay in the Chinese reserve. When he returned in May, Swaisgood had logged dozens of hours observing the Wolong pandas' sexual interplay. Swaisgood also conducted a number of structured behavioral studies within the community. This spring, for instance, he continued to probe the function of the panda scent marks.
When the zoo reworked its application to import Shi Shi and Bai Yun, studying scent marks was at the heart of the proposed panda research. Don Lindburg says that back in the 1970s staff at the National Zoo in Washington, D.C., had observed their pandas making the marks and recorded something about the frequency of the activity. But in the mid-1990s, neither the biochemistry nor the significance of the scent marks had yet been studied — even though it seemed obvious to panda-watchers in the wild that the scent marks must serve as an important survival tool for the animals.
When Swaisgood went to Wolong in the spring of 1997, part of his mission was therefore to find out more about the kind of information conveyed by the scent marks. “Picture a panda walking through the bamboo forest and coming upon a scent mark from another panda,” he says today. The first thing it probably wants to know is whether a male or a female made the mark. On the scent mark communicate that?
To find out, Swaisgood took pandas out of their pens, then brought in other pandas and recorded the responses of the newcomers. He found that males spent more time smelling the empty pens of females and vice versa. “I did this many times with many different pandas,” he says, and the response was consistent. “What’s even more interesting is that I found if I brought a female that was in heat into a male’s pen, her rate of chirping and bleating went up. This tells me that the males’ scent alone can facilitate sexual arousal in the female.” Males, in turn, bleated more when they smelled the marks left by a female in heat.
While it’s important to be able to tell the boys from the girls, Swaisgood points out the value of being able to identify particular individuals. If you’re a male panda, knowing that the creature that left the scent mark is another male panda “doesn’t tell you that much,” Swaisgood says. “Is it a male that’s dominant to you or subordinate? Is it a new male — an intruder and you might have to worry about him taking over your territory? Or if it’s a female that has come into estrus, it’s very important to know which female, because then you’ll have a better idea where to go look for her.”
Swaisgood did another study to find out if pandas can indeed recognize individual scents. He says he began by going into a male panda’s pen and rubbing its scent on a small piece of board. He took this into a female panda’s pen. “She picked it up and smelled it very intensely. She rubbed it on her head. She kind of knocked the board; licked the board. Very, very intense and prolonged interest in the scent.” The next day, Swaisgood offered the female the wood again and found her still interested, but less so. He continued to repeat the offer for three more days. “I had a little graph that was really beautiful. Each day she was exposed to this scent from the same individual, she became less interested.” On Day Six, however, he presented the female with two boards, one containing the now-familiar scent and the other containing one from a new male. “She pretty much ignored the first scent, because she’d habituated to it.” Instead, she focused on the new smell. Swaisgood says he did this with about 20 pandas, and they all showed the ability to distinguish between a familiar scent and a new one. “And they could do it with scent marks and with urine, both males and females.”
If the Wolong breeding center has been the primary locus for the San Diego Zoo’s investigations into what the scent marks mean to the pandas, work toward understanding the chemistry of the scent marks has been concentrated in the CRES building in Balboa Park. Lee Hagey has been at the center of that effort.
An analytical chemist, Hagey was a graduate student at UCSD when he met Dr. Kurt Benirschke, the UCSD professor of reproductive medicine and pathology who helped to found CRES in 1975 (and who today serves as president of the zoo’s board of trustees). After working on several projects for Benirschke, Hagey got a job at CRES about a year before the arrival of Shi Shi and Bai Yun. The chemist says at that point no one had ever analyzed the chemical makeup of the giant panda scent marks. “But the same statement could be made for 5000 other species,” he adds. “Probably the entire scent-mark literature includes less than 50 [mammal] species.” These range from ones of commercial interest such as the musk deer to attention-grabbing species like skunks. The compositions of scents of some common domestic animals such as dogs and cats have also been analyzed, though not in great detail. “For one thing, the instruments needed to do the work correctly have really only come about in the last couple of years," Hagey says.
In contrast, insects and the pheromones that they produce have attracted a lot of interest from chemists, in part because the pheromones have been seen as a potential source of control over insects. Also, because pheromones consist of “one or at most two very specific components,” they send a simple message. “It’s a ‘Come and get me’ message,” Hagey says. But mammals emit scents. “And scents by nature are complex.”
From a chemical perspective, “You could say pheromones and scents share a common goal,” he elaborates. “They both want to get into the air.” They also don’t want their message to be dispersed too fast. “If someone’s cooking hot popcorn in the microwave, you’ll get the message. But it won t last very long.... If you’re an animal sending out a message, you want it to persist —but not forever. You don’t want to be dead for five years and have your smell still be there.”
“Smells aren’t just random molecules,” Hagey says. “'They’re molecules with a purpose. They’re designed to survive in a forest and they’re designed to attract, lust imagine a lady giant panda. She lifts her leg and urinates on the forest floor. Now imagine you’re the male panda. How many different animals do you think have urinated on the forest floor in the last week? Thousands! Everything from the giant Chinese takin to the jungle fowl or the squirrel or the rabbit. Thousands of animals! And all those urines are chemical messages talking to their species, saying, ‘Go away, I’m the biggest, baddest guy in the forest.’ Or ‘Come along. I’m an eager female.’ ”
On top of all the animal scents, plants also emit odors. “The essence of pine. The essence of bamboo. The essence of dead leaves and ground and soil.” The male panda has to make sense of this olfactory jumble with his nose. “We humans are primates,” says Hagey. “We use our big old eyes to see that red bird there in the middle of those green trees. For a giant panda, the forest is pretty much black and white. But if we could see what he smells, there would be phosphorescent yellow or orange trails like smoke on the ground, trails that we could follow just as easily as if they were colored flares.”
To study the chemical makeup of panda scents, Hagey needed samples of the panda scents. He says his first ones came directly from the scent glands located beneath the animals’ tails. When Shi Shi and Bai Yun arrived at the zoo, they were anesthetized so that they could undergo a physical exam, and this gave Hagey the opportunity to scrutinize the critical area. It contains no little bag, such as skunks have, he says. “It’s more like an armpit. It’s an area where there are deep folds and channels.” But panda scent is more volatile than human sweat. “I can collect a drop of human sweat,” Hagey says. “But you can’t get a drop of giant panda scent. There isn’t any such thing.” Panda scent glands contain no more liquid than “your armpits do after you’ve showered and dried.”
Despite its evanescence, the panda scent hasn’t proven hard to collect from Bai Yun and Shi Shi’s enclosures. “Let’s say an observer sees the giant panda making a scent mark,” says Hagey. “He makes a mental note, and a couple of hours later after the pandas are in another enclosure, one of the keepers will go out and just rub that spot with a Q-Tip.” Hagey says some female human researchers who’ve sniffed such Q-Tips have detected a slightly musky smell. “But if you didn’t know it was a scent, you’d never identify that. If I gave you two Q-Tips, one with the scent mark and one not, chances are you couldn’t tell.”
Hagey, of course, doesn’t use his nose to analyze the panda scents. Instead, the scent collectors put the Q-Tips into glass bottles and freeze them. Hagey later thaws them out and inserts a needle into the bottle through a little rubber opening. Inside the needle is a tiny silicon sponge that emerges when Hagey pushes on a little plunger. “It kind of samples the air that’s coming off the Q-Tip.” After half an hour or so, he retracts the sponge and withdraws the needle, then he sticks it into the injection port of a gas chromatograph mass spectrometer. Inside this apparatus, the scent is evaporated off the sponge and separated into individual components. The mass spectrometer generates a picture that shows “a bunch of peaks.”
“You can instantly recognize the pattern,” Hagey says. “You can tell right away that it’s a giant panda scent mark.” He says the peaks in the pattern represent different chemical compounds. “And the mass spectrometer actually looks inside each of the peaks and gives me dues as to what kind of molecules made them.” From those clues, Hagey says he’s been able to figure out the identity of 20 component molecules in the male giant panda’s scent. Fifteen of the 20, it turns out, are products of bacteria that sit in the folds and crevasses of his scent gland. There, “it’s warm,” Hagey says. “It’s dark. It’s moist. It’s heaven. In a sense he’s feeding them the liquid he’s secreting. They eat it, and they kind of poop out the scent for him.”
The resulting product is fairly long lasting, and that makes sense, says Hagey. “His is a territorial message, and he’d like it to last long enough for him to make his circuit. It might take him a week or two to patrol his territory." Female panda scent marks are another matter, Hagey has learned. For one thing, they’re delivered differently. Male pandas rub their scent glands on objects in their environment, and their tails assist them in this action. “Ever think about why a giant panda has a tail?” he asks. “It’s not to keep flies off, right?” Instead the males use their tails like fluffy little paintbrushes. “They rub up and down and paint their little spot.”
Female giant pandas urinate to make their presence known. Hagey says when he analyzes their urine with his equipment, he sees “just the lightest and the faintest little dusting” of the scent-mark pattern, superimposed on a far more complex urine pattern. The latter probably includes some 200 compounds, and the resulting message is both more complex and more under the control of the panda (as opposed to the bacteria). “It’s a quick, instant report on her reproductive status. It says, ‘Here’s how I was yesterday or a few hours ago.’ ” Hagey says so far he’s identified around 25 of the 200 olfactory compounds in the female panda’s urine. In contrast, he says he could fabricate the male’s scent tomorrow. “It’s quite easy. It’s just like making a cake. I look at my compound list. I need 50 percent of this, 40 percent of that,” and so on. Put them together, stir them up, and voilà Eau de Giant Male Panda.
Hagey says he can’t yet tell you exactly which male panda scent he’d be creating. Given a scent mark, “I can tell you ‘giant panda,’ no problem. But to say, ‘This is Charlie or Fred,’ I’m in trouble there.” In another department within CRES, however, other scientists have figured out a way to read the I)NA within a given scent-mark sample—and thus to link it with a specific individual.
Geneticist Oliver Ryder presides over this sphere of activity. While studying at UCSD, he also came to know Kurt Benirschke, and after Ryder got his Ph.D. in 1975, he says, “I approached [Benirschke] with the question, ‘Is there something a molecular biologist can do for conservation?’ And he said, ‘Yeah, there is. But you’re going to have to invent it.’ ’’ Ryder decided to try, and he adds, “That was the best decision I ever made.”
The 23 years since then have been “a fascinating time to be a molecular geneticist!” Among other things, Ryder established a state-of-the-art DNA-analysis lab in the CRES building, and he’s been applying to animals the techniques developed for working with human DNA. “We’ve written the book for a number of species,” he says. “Including giant pandas.”
Ryder says the genetic work on pandas originated before the San Diego Zoo sought a long-term loan of the animals. At a scientific conference in China around 1990, Ryder met an eminent Chinese wildlife geneticist who told him about a talented student of his. This fellow, Ya-ping Zhang, was working on genetic questions involving rhesus monkeys and pangolins, but he had run up against a technological wall. He and his colleagues “knew there were techniques available that should be applied to [his work], but they didn’t have the resources to do it,” Ryder explains. So the zoo invited Zhang to come to San Diego. It took him several years to get a visa, and when he finally arrived he had finished up the monkey and pangolin studies. “We basically had a chance to start something new,” Ryder says. “We decided we’d work on giant panda genetics.... Pandas are very important in China, and one of the things we were trying to do was to give Ya-ping a very productive work experience here and training that would allow him to assume a role of responsibility and influence in China.”
Although the San Diego Zoo didn’t have any giant pandas at that moment, Ryder did possess tissue samples from Basi and Yuan Yuan collected during their stay here. He also had obtained postmortem tissue samples from the National Zoo’s ling ling and Hsing Hsing, as well as from all five of their offspring (none of which survived). Every cell in every one of those samples contained the full sequence of giant panda DNA — a huge string of information that Ryder likens to the contents of a phone book. By that analogy, it’s a phone book that varies in small ways from one individual to another. The variation is what creates the differences between the individuals of any given species.
Ryder says the “phone book” for any member of any species is “too big, too heavy, too much to deal with in its entirety.” So geneticists “tear it up into pages and deal with it a page at a time.... What you can do is pull (sections of the DNA) out and copy them I using the polymerase chain reaction, which La Jolla resident Kary Muliis got the Nobel prize for developing]. And that’s what Ya-ping did. He made this DNA library.”
Ryder says some “pages” of the giant panda DNA that the Chinese researcher fished out varied a lot from one individual to another. This was critical information. It enabled Zhang to develop tools for identifying individual pandas from DNA samples. But it would be far easier, Zhang and Ryder knew, if the DNA could be extracted from a by-product of the panda’s body, such as hair, rather than from hard-to-obtain blood or skin.
To obtain hair samples, Ryder traveled to China and collected them from 31 of the 100 or so pandas kept in zoos there. When he got the hairs back to San Diego and Zhang used the tools he had developed on them, the technique “worked like a charm,” Ryder says. He adds that the chances of the technique declaring two randomly selected giant pandas to be genetically identical are 1 in 300,000. With only about 1000 giant pandas alive in the world, “This is pretty good resolving power,” Ryder says.
Since doing this work, Zhang has returned to China where “he’s really a big shot now,” Ryder says with pride. “He’s got a bigger lab, more money, more students than I do." The Chinese scientist has since sent Ryder one of his students, who last year succeeded in getting DNA information from panda scent marks and feces. Ryder says it hasn’t been as easy to extract DNA from these as it is to extract DNA from hair. “'Die bottom line is…we’re going to have to work harder to get the same amount of information out of feces or scent marks.”
He says another Chinese postdoctoral researcher will arrive soon to work on this challenge. Ryder wants to develop tools so that the Chinese can do this work in their own country. He says the DNA lab at CRES “cost half a million bucks to set up, and it takes somebody who’s skilled to run it. But what I want to do is to go the next step and make a test kit”—something that might cost, say, $ 10,000 and be easy to use. “Now, to make this $10,000 setup I estimate is going to take another quarter-million dollars. But it’s really eminently doable. It’s absolutely no different from technology that is used routinely now in hospitals to see, for example, if people are carriers of cystic fibrosis.” Nobody has yet developed such routine tests for endangered species. But Ryder thinks it makes sense for such work to move forward “on some of the high-profile candidates first. And there is probably no higher-profile candidate than the giant panda — the supreme symbol of conservation.”
As for the practical uses to which the technology can be put, Ryder mentions one that he calls “genetic remote sensing.” He explains, “If you’re out trying to census the [panda] population and you find feces in two places, it could be either that there are two individuals pooping or one individual pooping twice. When you never see the animals, there’s statistical error.” The DNA techniques could eliminate errors and make it easier to determine how many pandas are left in the wild. Although high-tech censusing hasn’t been done yet, the DNA techniques have been used to clear up the uncertain paternity of some of the baby pandas born in Wolong to panda females that were both artificially inseminated and mated with panda males.
Ryder explains that the Chinese have combined natural breeding with artificial insemination because they’ve believed that the combination increases the animals’ reproductive success rate. The San Diego scientists have a different philosophy, one that assumes that natural matings alone are preferable. But the San Diegans also acknowledge that, for a variety of reasons, natural matings don’t always take place, and when that happens, artificial insemination can sometimes lead to the birth of another panda.
However, knowing when to inseminate a giant panda is tricky. On the one hand, female pandas offer lots of behavioral clues that their bodies are getting ready for an injection of giant panda sperm. As estrus approaches, they begin to splash around in water, something they don’t do much the rest of the year. They bleat and chirp with greater and greater frequency. They take to walking around backward, and on the days right around their ovulation they may raise their tails and back into the closest male panda. On the other hand, if a zoologist tries to artificially inseminate a female panda just one or two days early, the anesthesia required for the procedure can stop the ovulatory process. And within hours after being released, the panda’s eggs start to die. Ryder says the Chinese have tackled the problem of knowing when to artificially inseminate by doing it right “after a very responsive male performs a natural breeding.” In contrast, San Diego researchers have been working to develop other tools to help them pinpoint the day of the female’s annual egg production.
An important indicator is the amount of estrogen that the animal is producing (which typically peaks just before ovulation). Back in the late 70s, CRES scientists started developing ways of getting this information from urine samples, rather than blood. Endocrinologist Nancy Czekala says over the years she and her colleagues have learned that “each species metabolizes the steroids made by the ovaries and the testes a little bit differently.” Not only do different species make different compounds from the steroids, but depending on the species, those compounds may be eliminated in either urine or feces. Although a few species have confounded the scientists, Czekala says when she and a colleague at the National Zoo started working with panda urine, they found it easy to assay the estrogen within it.
When zoo staff members began preparing for the arrival of Bai Yun and Shi Shi, they built urine-collecting receptacles into the animals’ quarters. As soon as the pandas arrived, the CRES members began recording the estrogen levels found each day in Bai Yun’s urine. But they also wanted to discover what effect her estrogen had on her vagina, and for this task they’ve enlisted Bai Yun’s help.
One sunny recent morning, the female panda showed off her willingness to cooperate. She was up in her favorite tree when Kathy Hawk, the head panda keeper, called her down from it and over to a chain-link passageway. Bai Yun moseyed along through this corridor, finally entering a steel-barred cage known as a “squeeze box.” Once the keepers secured its doors, they coaxed the female into sitting upright. Then they adjusted the cage walls so she couldn’t scoot out of reach.
She sat with her paws against the cage bars, her huge head and perky ears erect, accepting chunks of apples and carrots and yams from the keeper’s fingers. The panda produced loud, juicy noises as she crunched these tidbits. In the meantime, a CRES laboratory assistant guided a swab through the thicket of dark hair below her belly. “Come on, sweetie,” the keeper crooned in a voice that women direct toward babies and very young children. “It’s okay. That’s a good girl!” Within moments, the lab assistant had slipped two swabs into the hidden orifice. Though Bai Yun usually curls her toes when the probe is penetrating her inner regions, the keepers say she’s never displayed anger or distress. Once she reached down and plucked the swab out. But then she calmly handed it to one of her attendants.
Barbara Durrant, the head of CRES’s reproductive physiology department, says the cells on the swabs are transferred to slides and treated with a Pap stain. Most of the year, when Bai Yun’s estrogen levels have been low, the cells have looked small and blue, with well-defined nuclei. As the estrogen levels have started to rise each spring, however, the cells have become more angular and pinkish, and by the day of ovulation, they’ve come to look more like squares of pink and yellow tissue paper than like cells.
Durrant says pandas don’t menstruate, but Bai Yun’s vulva underwent dramatic changes both this spring and the last one. The normally small, grayish sexual organ at first took on a pink cast, then grew larger and redder. “One day Bai Yun was up in a tree with her legs apart, and from a mile away, you could see that vulva,” Durrant recalls — which makes sense, she adds, considering the isolated lifestyle of pandas in the wild.
Last year on April 23 the level of estrogen in Bai Yun’s urine was more than ten times its normal level. The next day it fell all the way back to normal, a sign that the female panda was ready to be mated. She seemed to confirm that readiness by soliciting Shi Shi for sex more than four times an hour (according to the observers’ calculations). Still he rebuffed her, sometimes by moaning and moving away, sometimes by swatting at her and trying to bite her. The CRES researchers could only look on in frustration, but this year when the same scenario unfolded on the morning of April 8, they were prepared to intervene. Having secured permission from both the U.S. federal government and the Chinese panda overseers, zoo staff directed Shi Shi into his enclosure, then they shot him with a dart that put him to sleep.
The dart hurts no more than any routine injection, Durrant says. “It’s no big deal, really.” Once Shi Shi was unconscious, workers transferred him to the zoo’s hospital, and there Durrant inserted into the male’s rectum an electric probe that stimulates the nerves and the muscles in and around the penis and the accessory sex glands. This method of obtaining the animal’s semen is not foolproof, Durrant says, nor does it work equally well with all species. “The rhinoceros is almost impossible,” she says. “And dogs you pretty much can’t electro-ejaculate because they’re missing one of the major accessory sex glands.”
She says the technique works pretty well on pandas, although it may not produce as much ejaculate as a male panda would if left to his own devices. No one knows what the normal ejaculate volumes are, Durrant says, because no one has ever trained a panda to ejaculate into an artificial vagina.
The zoo has done this with numerous exotic species, and Durrant says she’d love to try it with Shi Shi. “It would be a great source of sperm for banking and experimenting.” She adds that it would be easy to fabricate an artificial panda vagina. “We’ve made artificial vaginas for all kinds of species.” The tricky part is likely to be finding something that would cause Shi Shi to have an erection, a necessary first step in the training process. “Some animals are stimulated by the presence of certain keepers,” Durrant says. The sight of food causes erections in others, “and we can take advantage of that.” The keepers haven’t yet noticed Shi Shi having any such spontaneous reactions, according to Durrant, though she’s hopeful that if the keepers can train Shi Shi to go into the squeeze box, they may find something that will arouse him. “With some rhinos, you can get them to drop their penis and get an erection if you scratch their belly or their back or something like that. So it’s possible that if we can get our hands on him a little bit closer, we can find something that may work. And then we’d take advantage of that. Reinforce it.” Soon ejaculation becomes its own reward, the scientist adds.
Whether obtained via masturbation or electro-ejaculation, the quality of various animals’ semen samples can vary, but Durrant says the ejaculate that she got from Shi Shi on April 8 appeared to be excellent. Since artificial insemination requires inserting the semen directly into the female’s uterus, the semen sample has to be washed and filtered to minimize any risk of infection. Durrant says this process too went well. After Bai Yun was anesthetized and brought to the zoo hospital, Durrant had no trouble getting the insemination rod through her cervix and up into her uterus. As an extra precaution, she repeated the procedure on Bai Yun the next day, using some of Shi Shi’s semen that had been held in reserve.
Since then, the CRES scientists have had to be patient. Giant panda pregnancies have a strange feature known as “delayed implantation.” After fertilization, the egg starts to divide but the blastocyst very soon stops growing. It floats in the uterus in a state of suspension. Only after attaching to the uterine wall sometime later does it begin to grow and develop again. In June, the zoo staff began doing ultrasounds on Bai Yun to detect any such growth, but so far this testing has been inconclusive.
Looking forward to a birth, Don Lindburg appeared to be braced for someone to complain that it was just a publicity stunt. “But it really is about conservation,” Lindburg argues. Had the San Diego Zoo forgone the opportunity to do the artificial insemination, it would have wasted another year of Bai Yun’s reproductive potential, he says. Beyond that, Lindburg asserts that he believes “there’s nothing like a pregnancy to confirm that you really are understanding what all these hormones mean or what all this change of behavior means. It’s kind of a validation in the absence of a validation from a viable male.”