The National Zoo's giant panda cub, Tai Shan, didn't just happen -- he was brought to you by scientists who spent years studying the intimate details of black-and-white bear biology before they mastered artificial insemination.
A recent surge in giant panda science is helping zoos get more animals pregnant, diagnose when they are expecting and put to rest the long-held belief that pandas are poor breeders. The research is producing insights into how pandas communicate, how mothers raise their young and how the animals look for food.
The ultimate goal is to increase the giant panda's chances in the wilds of China, where only about 1,600 remain, threatened mainly by the loss of bamboo forests to logging and development. Scientists are studying the panda's basic survival needs and are trying to build up the number of captive animals so that some could be set loose in potential panda territory.
Money for the studies has come largely from the four U.S. zoos that have giant pandas -- including the National Zoo, where Tai Shan goes on public display today.
"I am not sure we know of any endangered species where we have this amount of information," said National Zoo senior scientist David Wildt.
In a recent interview, a high-ranking Chinese wildlife official, Yan Xun, underscored the cooperation between U.S. and Chinese scientists: "We have achieved a lot of accomplishments," he said.
Tai Shan's birth in July was the result of years of research efforts. Many experts believed that giant pandas were poor breeders because they seldom got pregnant in zoos and because females are fertile only two or three days a year. But that idea crumbled after U.S. and Chinese scientists examined dozens of captive pandas in the late 1990s and found most biologically fit to breed.
"We have every reason to believe that pandas in the wild are doing all right as far as opportunities for pregnancy are concerned," said Donald G. Lindburg, head of the giant panda team at the San Diego Zoo, where three cubs have been born. "This is more of a captive phenomenon."
Artificial insemination is one way around the obstacle of persuading pandas to breed naturally. National Zoo scientists have been working since the 1980s on monitoring hormone changes to tell whether a female is fertile. Scientists there and at other zoos ramped up the research in the late 1990s, when China began lending panda pairs to U.S. animal parks.
National Zoo keepers trained their female, Mei Xiang, to sit still for medical tests. Scientists created a mobile lab to track hormone changes in her urine and improved testing to get results faster. They watched for behavioral changes that indicated she was ready.
"Short of crawling inside her abdomen," reproductive scientist JoGayle Howard said, "I don't think you can get any better timing."
Zoo scientists hoped that Mei Xiang and the male panda, Tian Tian, would mate naturally last spring, but when that did not happen, they stepped in as the female's short window of fertility was about to close. Howard e-mailed regular updates of Mei Xiang's test results to San Diego Zoo scientists, who suggested a specific time to perform artificial insemination.
With Mei Xiang under anesthesia the morning of March 11, Howard employed a tiny laparoscope with a light to perform the procedure, the first time that particular type of instrument was used on a giant panda.
"It's remarkable," Lindburg said. "They had one vial; they had enough sperm for one insemination. They had a single event, and they nailed it."
Zoo managers would prefer that pandas breed on their own, and one line of research is trying to foster that. A major discovery is that pandas get to know each other through their noses. A male panda can tell whether a female is in heat by sniffing her urine or the scent marks she leaves behind. Each panda has an individual scent.
In the past, zoos raised males and females separately, putting them together only for mating. Often, that resulted in fights, not cubs. "When animals are introduced for breeding, they need time to become familiar with each other, scent-wise, before they are put together," said Rebecca J. Snyder, curator of giant panda research at Zoo Atlanta.
So Chinese zoos often keep several young pandas together so they can get to know each other as they grow up. The zoos also let breeding-age animals sniff each other's scent before meeting. Some scientists think this research suggests that if giant pandas were reintroduced in the wild, their chances would improve if their scent were spread around their new territory beforehand, staking their claim.
Scientists also have studied panda personality. Former National Zoo researcher David Powell, now at the Bronx Zoo, developed an exam intended to give zoos rapid assessments of how to care for new animals. He tested 38 pandas in China to measure their general activity, along with their level of interest in a new toy.
"That will tell you right away this animal adjusts well to change, or I have to be quiet around this animal," Powell said. "We've made a lot of progress in behavior management and husbandry."
Long range, some zoo scientists think the personality test could help them improve panda breeding -- they could, for example, provide hiding places for a shy female that might be reluctant to mate.
Zoos still haven't solved the mystery of knowing when a giant panda is expecting. It was not until Mei Xiang gave birth that the National Zoo knew for sure that she was pregnant. Scientists would like a definitive pregnancy test so they can reduce stress on animals that might lead them to abandon their young, which weigh only a quarter-pound at birth.
Hormone tests still cannot detect the difference between a real pregnancy and the common false pregnancy in pandas. Ultrasound is promising, but some pandas won't sit still for it. San Diego scientists are experimenting with a technique called thermal imaging, measuring whether a mother's blood flow is increasing, which is one sign of a developing embryo.
"We're still doing very basic work with the giant panda," said National Zoo research veterinarian Steve Monfort. "We still have a long way to go."
Snyder, the Atlanta scientist, has looked at how mothers raise their young, finding that they hold their tiny infants 80 percent of the time during the crucial first three months. Males and females are raised differently, she concluded. And, so far, she has found little difference in mothering style between experienced and new mothers.
Other studies focus on how pandas look for food and what they like to eat. Bamboo is their main diet, and they spend much of the day eating because bamboo has so little nutrition that they need a lot of it. The Memphis Zoo is assembling a bamboo database of hundreds of samples and analyzing their nutritional value. The zoo also tested a variety of bamboo on its two pandas, hoping to offer guidance to wildlife managers scouting for places in which to reintroduce pandas to the wild.
"They switch bamboo species through the year and switch the parts they eat -- sometimes leaves and sometimes stalks," said Matthew Thompson, the zoo's large mammal curator. "In the spring, they like to eat shoots."
Most giant panda studies have been done on zoo animals, and the next frontier will be tracking the elusive animals in the wild. Chinese officials have been reluctant to allow giant pandas to be fitted with radio collars that would make it easier to track them.
"A very big question for all of us is whether or not the information we've gleaned from watching animals in captivity echoes what is going on in the wild," San Diego's Lindburg said.
But giant panda research has had another payoff. U.S. zoo scientists have trained dozens of their Chinese counterparts to test hormones, map panda territory on computers and learn other wildlife skills. National Zoo reproductive scientist Howard hopes that cheetahs, maned wolves and other rare species could benefit from the artificial insemination device she developed for Mei Xiang. Her colleague Monfort said zoos are developing hormone measurement tests for other types of animals, modeled on the giant panda work.
"We've got a lot of ideas now that we're ready to try on other species," Howard said.
The Procedure Scientist JoGayle Howard performs artificial insemination in March.
New Horizons Tai Shan, who is still nursing, samples straw last month.
Baby Makes Three Mei Xiang tends to her 4-month-old cub in November.
National Zoo veterinarians Suzan Murray, left, Sharon Deem and Ellen Bronson anesthetize Mei Xiang in preparation for artificial insemination. Until Tai Shan was born, doctors were not sure the procedure was successful.