First, they lead each rhino into a specially designed chute with an open panel at the rear. Since rhinos are so large, ultrasound won’t work through their bellies or flanks. You have to go in through the rectum, which means there is, quite literally, a lot of shit in the way. The rhinos’ trainers have conditioned each animal to defecate in the yard before the procedure, but Pennington and Durrant still have to spend a fair amount of time scooping poop out. Once they’re done, they insert a rounded probe that’s the size of two fingers, and is taped to a foot-long long PVC pipe.

The pipe, I suggest to Pennington, surely means that your arm’s not going in there.

“Oh, it is,” she tells me. A rhino’s ovaries lie deep within its body, and the left one, for some reason, lies deeper than the right. For the left ovary, Pennington typically ends up shoulder-deep in rhino. The animals aren’t sedated during any of this, but they seem unperturbed. “I’m sure the sensation is very odd at first,” says Pennington, “but the size of their fecal boluses are definitely larger than the diameter of our arms.”

It helps that white rhinos are docile and sociable by nature. “They’re like big puppy dogs, who just want to be petted,” says Pennington. “They’ll kick a leg out when you’re scratching their belly, and you’re afraid they’ll fall over because they really get into it.” Even for a white rhino, Victoria is affectionate and easy to train, Pennington says. She’s also particularly independent. Unlike some of her peers, who have such strong bonds that they have to be moved as a group, Victoria will readily show up for a medical scan on her own.

Such scans have been invaluable. They revealed that five of the six females were “flatliners”—that is, they weren’t releasing eggs on their own, and had to be induced with a hormone injection. The team spent a full year working out how best to do this. And when they tried the treatment on Victoria, she responded beautifully. On March 22, during one of her ultrasound checkups, the team saw signs of eggs. It was time to add the sperm.

Jill Van Kempen, Victoria’s primary trainer, led her out of the ultrasound chute and sedated her. Meanwhile Pennington donned a long glove. With an audience of around 20 people, including vets, students, and trainers, “I guided a catheter through her cervix,” Pennington says. “I just made it sound way easier than it is.”

Pennington had artificially inseminated horses and cows before, so she knows how to find the entrance to a cervix by touch alone. But a rhino’s cervix not only sits at the end of a much larger vagina, but is also incredibly convoluted. The cervix zigs and zags like a steep mountain road. To navigate these switchbacks, Pennington used a catheter with a 45-degree kink in it, and slowly steered it around the sharp corners.