In a year of tortured politics, nationwide protests, and a highly contagious pandemic, our troubled republic finally has something to celebrate. Washington, D.C., has a panda cub. Mei Xiang, a mellow matriarch who weighs in at two hundred and thirty pounds, gave birth to a tiny, hairless pink cub weighing just ounces, at 6:35 P.M. Friday, at the National Zoo. The wee panda, the size of a butter stick, introduced itself with a howling squawk. The birth defied the zoological odds—Mei’s advanced age, the life-long failure of her partner panda, Tian Tian, to figure out how to mate, the zoo’s inability to extract fresh sperm from him fast, and, especially, the many complications from the COVID-19 pandemic. A week after the pandemic forced the National Zoo to close, on March 14th, Mei began to ovulate. Most of the zoo’s staff were ordered to stay at home or reduce hours. In a race against time, a small team of reproduction specialists—all willing to risk the rules of social distancing—thawed eight hundred million sperm to artificially inseminate Mei, knowing that it probably wouldn’t work. “It’s overcoming the odds, and if there was ever a need for a sense of overcoming the odds, it’s now,” Brandie Smith, the zoo’s deputy director, told me. “People need this. It’s the story of hope, and the story of success, and the story of joy.”
The average lifespan of a panda—the world’s rarest and most endearing bear—is between fourteen and twenty years in the wild, according to the World Wildlife Fund. (The panda is its logo.) Mei is twenty-two years old. “Given her age, she had less than one-per-cent chance of giving birth,” Smith said. Only one older panda in recorded history—anywhere in the world—has had a cub. She was twenty-three; she lived in China, the homeland of the world’s pandas.
Pandas are notoriously poor at reproduction, which is one of the many reasons they were long endangered. Today, there are less than two thousand in the wild. To encourage sex, panda handlers in China have even tried giving males Viagra and showing them “panda porn”—videos of other pandas having sex—to the breeding pairs. Females only go into estrus once a year—and only for twenty-four to seventy-two hours. Unlike with humans, and many other mammals, including leopards, gazelles, and antelope, zoologists do not know how to induce or manipulate pandas’ fertility cycles. “We have to wait for nature to take its course,” Dr. Pierre Comizzoli, one of the zoo’s veterinary specialists in species preservation, told me.
This year’s timing couldn’t have been worse. Helping a panda reproduce is labor-intensive. Just determining if and when Mei goes into estrus is tricky, and even harder during a pandemic. The zoo has to collect her urine—with a syringe off whatever surface she pees on, when the two-hundred-and-thirty-pound bear isn’t looking—to test her hormone levels at the endocrinology laboratory. This year, her hormones peaked on March 22nd, during lockdown.
The zoo veterinary team had to move fast, because mating wasn’t possible. In 2004, when Mei hit puberty, the zoo tried to get her and Tian Tian to breed naturally. But Tian kept pushing Mei’s body down, rather than lifting it up to penetrate properly. The zoo got creative. It built wooden platforms and tried plastic cylinders to boost her body into the right position. But the two giant bears never did consummate. So the zoo, which has pandas, in large part, to study the reproduction and the preservation of the species, turned to artificial insemination.
In the past, trying to get Mei pregnant has required two teams employing the same equipment and catheters used for intrauterine insemination of humans—with a catch. “These are wild animals,” Comizzoli, who leads the operation, said. “You have to sedate them. They are big carnivores.” One team would sedate Tian and extract fresh semen. “Always better to get fresh semen, whatever the species,” Comizzoli, who has also successfully artificially inseminated an elephant, noted. A second team would anesthetize Mei, empty her bladder with one catheter, then deposit the semen in her uterus with another. Pandas also have notoriously small uteruses. “It goes extremely fast,” he said. “It takes a matter of minutes to inject the semen.”
The pandemic changed all that. The zoo assembled only one, smaller team. “This year, we wanted to minimize the number of procedures, so we had to go with frozen semen in our cryopreservation bank,” Comizzoli said. It had been there for five years. To help widen the genetic pool, the zoo has in the past inseminated frozen semen from pandas in China as well as Tian’s semen—double inseminations to increase the odds of a pregnancy. (Some artificial inseminations in China have used semen frozen from pandas who have since died.) But the three cubs Mei has produced since 2005 have all been from Tian’s fresh semen.
The zoo’s team risked their lives to inseminate eight hundred million sperm cells—from the billions the zoo has stored—hoping that one would reach and fertilize the one or two eggs that Mei produced. The zoo was skeptical. “The truth is that we know, in terms of biology, that after the age of twenty, it’s pretty advanced for reproduction,” he said. “Our female is at that time of life when, yes, there are less chances of carrying a healthy fetus.” Even at a younger age, Mei’s offspring had problems; only three of her six cubs have survived.
But on August 14th, Mei let zookeepers do a rare ultrasound in exchange for some of her beloved honey water; she usually balks at the latter stage of a pregnancy or pseudo-pregnancy (of which she has had several). It revealed fetal tissue. “We are totally surprised,” zoo spokeswoman Pamela Baker-Masson said, in an announcement. “Reproductively speaking, this is like a miracle.” The pregnancy was big news across Washington, too. Views on the zoo’s popular panda cam soared by twelve hundred per cent. On Friday, after news got out that she was in labor, the system repeatedly crashed.
Since China gifted the first pair of pandas to the United States, in 1972, the bears have become the city’s unofficial but beloved symbol—replacing both the donkeys and elephants that symbolize the parties that rule (at least technically) from the capital. Over the past week, the zoo set up a nursery, complete with three incubators, outside Mei’s nesting den. They prepared for the possibility of her having twins—and rejecting one. Twice, she has given birth to two cubs and one has died. Panda mothers often will nurse and pay attention to only one cub.
The contingency plan was to keep one in the incubator and try to swap it every few hours to let her nurse both. “If she has two, our plan is to swap,” Smith told me. “You have to sneak up on a giant panda and reach your hand under her belly and take one of the cubs off her. This is a bear that can crush a femur. It’s a dangerous endeavor.” If Mei refused to nurse one of the cubs, then the zoo would hand-raise it until it was viable on its own. The previous cub, the mischievous and spirited Bei Bei, had a twin, but it soon died despite the zoo’s efforts.
The future of Washington’s pandas is uncertain. The new cub—whose gender may not be known for weeks—arrived in the midst of contract negotiations with China. The pandas are technically owned by China and leased to the zoo. Mei and Tian originally cost a million dollars a year; now the zoo pays half a million annually. Each cub has to be turned over to China by its fourth birthday, under the zoo’s existing agreement with China. Bei Bei, an adventurous bear who dared fate by climbing high into trees even after he reached two hundred pounds, went back last November. The current lease on Mei and Tian expires on December 7th. The National Zoo, one of the few free animal parks in the United States, has to raise the funds to pay its panda fees to China, plus cover the costs of facilities, staff, food, and panda health care—including artificial insemination. Each panda eats some forty pounds of bamboo a day. For all the celebrating, the new cub was also bittersweet for Washington. “No matter what, this will be Mei’s last cub. It’s the end of an era,” Smith told me. “We’re a little melancholy because these pandas have meant so much to the city, to the zoo, and to us as individuals.”
