In the late 1930s, a grand panda drama unfolded at the Chicago Zoo. Su-Lin, who had been a media darling since she was a cub, passed away. Zookeepers were already in the process of procuring another female panda named Mei Mei, and they were determined to find her a mate before tragedy struck again. So when they acquired a prospective suitor named Mei Lan, it seemed their troubles were over. Magazines monitored their progress, and the public eagerly awaited the patter of tiny panda paws. But the wait dragged on. At first, headlines declared that Mei Mei was "getting nowhere" with her love life. But eventually zookeepers realized their significant slip-up: both bears were male.
This is just one of many mistakes humans have made when it comes to pandas. We've incorrectly classified them as raccoons, misrepresented them as cuddly vegetarians, and— since the doomed union of Mei Mei and Mei Lan— declared them as incompetent lovers. Some people have taken this even further, suggesting it's remarkable this sex-shy species has been able to sustain themselves at all. However, this common perception of pandas having low libidos actually has more to do with human incompetence.
When it comes to breeding pandas in captivity, zookeepers face multiple challenges. As the Chicago case suggests, it can be tricky to figure out a panda's sex. Their external genitals don't appear until they're a few months old, and once visible, they look very similar. This forces zookeepers to rely on inconsistent methods, like trying to measure the distance between the anus and genitals, or simply going by feel. And even when males and females are paired up correctly, chemistry isn't guaranteed. In one case at the Moscow Zoo, a female bear that had been isolated from other animals proved more interested in zookeepers than other pandas. Complicating things further, female pandas can only be impregnated 1 to 3 days each year due to their incredibly short ovulation window. Zookeepers try to track fertility levels by measuring the hormones in their urine, but this data is often cryptic to decipher and messy to capture. Females have also evolved the ability to reabsorb their own fetuses, meaning that even a successful impregnation can be reversed.
The difficulty of breeding pandas has reinforced the idea that they're not naturally inclined to procreate. But there's a huge gap between how these animals behave in captivity and the privacy of the wild. Prowling through her home territory, a female panda rubs her anal glands on tree trunks to attract mates, then waits in the treetops bleating as loudly as she can. Soon enough, males crowd around the tree and compete for her attention by seeing who can pee the highest. Suitors adopt a variety of poses in these competitions, including the "squat," "legcock," and "handstand." They're also known to dab urine behind their ears to broadcast their virility through the breeze. Once a female picks a winner, the mating pair will often have sex over 40 times in a single afternoon. At these rates, you might expect panda populations to be booming, especially since panda sperm is incredibly potent. But females' short ovulation cycles and ability to reabsorb fetuses keep the population in check.
In the wild, young pandas are usually able to witness at least one breeding season before reaching sexual maturity, giving them time to learn the rituals of seduction. But in captivity, pandas are never able to learn these customs. And while breeders have tried to kick start young pandas' sexual awakenings by showing them footage of mating elders and offering them doses of Viagra, none of these strategies have worked consistently. The most reliable approach they've found is artificial insemination, which has dramatically increased the captive population in the past few decades. But if pandas are so much better at reproducing in the wild, one has to ask why are conservation efforts so focused on breeding them. Maybe our time would be better spent protecting the pandas' natural environments, giving them all the space they need to get down to business.
