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Scientists find the secret to panda procreation: Love

Giant panda cubs are seen inside baskets at the Sichuan, China, giant panda breeding center where the study was conducted. (Reuters)

It is notoriously hard to get pandas to have sex.

This is a widely known, much-bemoaned fact in the world of animal conservation (and panda appreciation). Captive pandas may be charismatic and cuddly, but expert romancers they are not. Female giant pandas are fertile for fewer than three days a year — a pretty small window for, ahem, activities, especially when you consider that many captive pandas simply don’t know how to do it.

When keepers at the National Zoo tried to get panda couple Mei Xiang and Tian Tian to mate a few years ago, the duo proved themselves “reproductively incompetent,” David Wildt, head of the zoo’s Center for Species Survival, told the New Yorker magazine. Mei Xiang “pancaked” her body flat on the ground, making her lady parts inaccessible to her partner. And rather than trying to woo his mate by, say, mounting from behind or pulling her into his lap, Tian Tian just stood there, befuddled. In one case, he even stepped on her back — not really the best way to get your mate in the mood.

Zoos across the globe have tried to rectify this dire situation — baby pandas are at stake here, people! Not to mention the possible future of a species — with strategies that would make even your most interfering relatives blush. Some screen “panda porn” videos to encourage the bears (or at the very least to demonstrate proper technique). Others, such as the National Zoo, resort to artificial insemination. No one has yet tried couples therapy that we know of, but it may only be a matter of time. Meanwhile, panda matchmakers — this is a real job — scour a database of all of the world’s captive pandas to find the most genetically “suitable” pairings.

But in their eagerness to play yenta, zoos may be missing out on one crucial factor, scientists at the San Diego Zoo Institute for Conservation Research say:


When bears are given the opportunity to choose their own mates, researchers reported in the journal Nature Communications, they were far more likely to copulate and produce a cub. Couples in which both members showed an interest in one another had an 80 percent chance of becoming parents. Even when only one partner showed outward signs of affection, the likelihood of reproductive success was about 50 percent.

But when neither animal was interested in the other, zero babies were made.

[When pandas squeak and make other noises, what are they saying?]

The results probably won’t come as a surprise to anyone who has ever been set up — or, you know, has a heartbeat. Attraction is a complicated, fickle thing, and it can’t be boiled down to some zookeeper’s judgment of genetic compatibility (the panda equivalent of your mom saying, “Nancy’s son is the nicest boy, and he’s in medical school”).

But apparently this is news in the bizarre world of panda breeding.

“Incorporating mate choice into conservation breeding programs could make a huge difference for the success of many endangered species’ breeding programs, increasing cost-effectiveness and overall success,” Meghan Martin-Wintle, conservation biologist at the San Diego Zoo and a co-author on the study, told Reuters.

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The study examined more than 40 pandas at a conservation center in China’s Sichuan province. The bears were kept in open-air concrete enclosures with barred “howdy” windows and gates on either side, allowing them a peek at adjacent bears. This enabled researchers to conduct dichotomous choice tests on each panda.

The bears were then monitored for signs that they were interested in their neighbors. For example, a female panda might signal her interest by sticking her tail in the air and walking backward toward the male. The dude might signal back by scraping his foot or performing a handstand against a vertical surface and urinating. (Guys, please don’t try this at your next party.) All in all, there’s a lot of bleating, chirping, rolling around and splashing of water, as well as some more R-rated behaviors that may be best left to the imagination.

We went to China and found pandas in all stages of life from birth to cuddling with mom (Video: Lee Powell/The Washington Post)

During the females’ short fertility period, the animals were paired up according to genetic recommendations from the panda species survival plan (these plans help direct captive animal breeding to preserve genetic diversity and a healthy population as a safeguard against extinction in the wild). Some bears got matched up with their preferred partners, others did not. Male bears were introduced to females’ pens for anywhere from three to 75 minutes, then moved on to the next one whether they made it all the way, so to speak. Ultimately, each female panda saw an average of four suitors, though some had as many as nine. And after the nightmare speed dating session was over, every female was artificially inseminated as a fail-safe — the researchers would sort out the mess of paternity questions later using DNA tests.

During the mating sessions, female bears were roughly twice as likely to successfully copulate with their preferred partners. Surprisingly — dudes are generally seen as faithless philanderers in the animal world — the same was true for male pandas. They were also 100 percent more successful if they were courting a female they’d previously had cubs with.

[The perfectly sensible reason why panda mothers and other creatures selectively abandon babies]

At the end of the three-to-five month gestation period, only panda couples in which at least one member liked the other were able to produce a baby. Larger, older males were more likely to produce offspring, but that may be a side effect of the fact that they were more attractive and likely knew what they were doing (unlike hapless Tian Tian). And moms that had been raised by their own parents, rather than zookeepers, were more likely to rear their own cubs.

The success of panda breeding programs is crucial because China is working to release some giant pandas back into the wild. Fewer than 2,000 of the bears exist outside conservation centers and zoos, according to the World Wildlife Fund, but they’re needed for their role in their ecosystem, mostly spreading seeds and boosting vegetation growth. And, conservation scientists argue, pandas belong in the wild. (For one thing, wild pandas are a lot better at procreating than their captive counterparts).

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But life is risky for a captive panda brought back into the wilderness — last year, the only panda successfully released by China fell ill and died after just a month on her own. The program’s first participant, Xiang Xiang, was reintroduced to much fanfare in 2006 but was found beaten to death by a wild panda one year later. Three other reintroduced pandas seem to be doing well.

To keep up the reintroduction program, and to keep the population of captive pandas large and diverse, zookeepers need to make sure that pandas reproduce as often and as successfully as possible.

Co-author Ronald Swaisgood, also of the San Diego Zoo, said that the findings from the study can help breeding programs pursue that goal.

“The pay-off will be higher reproductive rates and more baby pandas,” he told the New Scientist. “When a zoo is struggling to get its pandas to breed, it might be possible to switch out one of the pairs to see if a behaviorally compatible pair can be found.”