Pandas tend to have difficulties mating in captivity, necessitating complex architectural solutions to keep males and females separated at all times, except during the female's brief oestrus.
It is also important to have a joint area that pandas alternate between accessing. There, they will leave hormonal traces and zookeepers can monitor the animals' reactions to each others' scents.
Disegno has previously covered some of the intricacies of the architecture and politics involved in designing for pandas.
Ying Ying and Le Le had been subject to previous efforts of artificial insemination, which led to a series of miscarriages.
The giant pandas were seen "cuddling more intensely than usual" on Monday morning, writes the Guardian. They mated on the same day, "much to the delight of park managers."
“The successful natural mating process today is extremely exciting for all of us, as the chance of pregnancy via natural mating is higher than by artificial insemination,” said Michael Boos, executive director for zoological operations and conservation at Ocean Park, in a press release.
Zookeepers have not suggested that the absence of crowds surrounding Ying Ying and Le Le's pens is in any way connected to the happy news. Instead, they say that the pandas had been involved in "years of trial and learning".
This has not stopped international media in drawing conclusions about how panda sex works. "The pair made the most of the privacy," the BBC reports. "Pandas Take Full Advantage of Lock Downed Zoo, Finally Have Sex", runs the Huffington Post's headline. And "Finally, Some Privacy: After 10 Years, Giant Pandas Mate in Shuttered Zoo" from the New York Times.