After an auspicious start on Sunday, which began with an early breeding between giant pandas Bai Yun and Gao Gao, San Diego Zoo staff had planned to give our pandas a break of several hours to rest. After the high level of physical exertion associated with breeding attempts, rest periods help recharge the bears’ batteries. The pandas grab a quick snack and a catnap and wake up feeling refreshed.

Somewhat unusually, Gao Gao maintained a very high level of motivation after that first breeding, refusing to rest. He motored about his exhibit, bleating and checking the howdy gate. He grabbed an occasional drink or bite to eat but kept his focus on his mate. Bai Yun, for her part, kept close to that gate, rear-presenting and making it clear she would be happy to have Gao Gao with her again. In order to take advantage of their obviously high level of arousal, we opted to skip the break period and allow them access to one another sooner rather than later. It paid off. At 10:29 a.m., a second mating was achieved.

Staff was elated. Both bears were doing well, we had two matings under our belt, and it wasn’t even lunchtime yet. Despite the crazy weather (it was hailing on us at one point as we watched the bears wrestling in the drizzle), our charges seemed focused, strong, and willing. Surely now that they had managed to copulate twice, they would want to take a break, right?

Wrong. Maybe Gao Gao worried that Bai Yun might have weaker motivation the next day. Or maybe he was aware of his own tendency to be a little slower the day after breeding, feeling the effects of muscle fatigue and soreness. Or maybe he just likes his girlfriends covered in mud. For whatever reason, our boy just would not settle down! He continued to pace and bleat and paw at the gate when she was near. Bai Yun continued to bait him at the howdy gate.

It was decided that if the bears were up for it, we should let them have another shot. Again the gate was opened. For some time, the two worked the mating dance without success. The rain poured down some more, and the wind blew dried bamboo stems down from the stands surrounding the exhibits. And still they worked at it. Ultimately, they did not succeed, so we separated them again to reset the stage.

Almost comically, the bears again refused to leave each other alone. Really, Gao Gao? How can you be so undeterred by the mud and wind and rain? We are soaked through and exhausted just watching you. Didn’t anyone ever tell you that you are a senior bear? But I digress.

After much debate, we opted to go with Gao Gao. Up went the howdy gate, down came the rain. They interacted for another half hour or so, but again no mating was realized. Surely, they must be done for the day, we thought. They had to be tuckered out by now. But…well, I think you can guess where this is going!

His motivation still urgent, Gao Gao was letting us know he was still very interested in Bai Yun. Some of Bai Yun’s sexual behaviors were still building in intensity, which was encouraging. However, as she tired, Bai Yun had seemed more and more slow about adopting a posture of lordosis, in which she lowers her shoulders to the ground. Let’s face it: Gao Gao, for all his vigor, isn’t a very big boy. If our female doesn’t get low to the ground, all the vigor in the world just isn’t going to help.

Maybe this was a factor of her age (“Oh, my aching back”), or perhaps the weather conditions (“It’s muddy and wet down there”). For whatever reason, Bai Yun was not as cooperative as Gao Gao would have liked, and this was a contributing factor to their lack of success midday.

Persistence pays off, however. The fifth time(!) we paired our bears, Gao Gao managed to coax Bai Yun into the proper position. He finally accomplished what he had been working so hard to achieve for the last few hours. A third copulation was realized at 1:28 p.m.

Sunday afternoon, we sealed the howdy gate between the bears and left them with a heavy feed. Our hope was that they would fill their bellies and rest. Ideally, we would like to see one more mating out of this pair, not because three isn’t a good number (it is!), but because we are interested in seeing if we could spread out the timing of their breedings a bit to ensure we catch that egg when it is released. The precise timing of ovulation in the breeding cycle is still a bit of an enigma to us, and we would like to have a wide breeding window to maximize the likelihood of fertilization. So we decided to come in again on Monday and try again.

Did Bai Yun remember to get her shoulders down? Did Gao Gao wake up too tired to try again? Did the hail return to spice things up? What happened on Monday? You’ll have to wait until my next installment to fill in those blanks. Right now, I’m going to crawl under a (dry) warm blanket and catch up on some rest myself.

(Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research.  Read this article and more about the San Diego Zoo pandas at The Giant Panda Blogs.)