Bai Yun’s estrus is progressing, with a mixture of the dampened behavior we saw in 2007 and the heightened behavior we have seen in previous years. Her rate of scent marking was high over the weekend, but today, April 13, on exhibit we haven’t seen anything of the sort. She is probably past the time when scent marking begins to drop off, and we would expect her vocalizations to kick in soon. As of this morning, however, very little bleating and no chirping has been heard.
Behavioral indicators aren’t the only measures of her estrus we are tracking. Some of her physical traits also show us that her hormones are very actively preparing her for breeding.
Today our howdy gate was opened for the first time, and Gao Gao checked it out several times in the first few hours. At first, his visits were very brief and included a short “hello” bleat. Bai Yun noticed him within a few minutes, stared at him a moment, then went about her business for the rest of the observation period. Gao’s visits became more regular, and before long he was scent marking at the gate and standing there, admiring Bai Yun from a distance. Always the gentleman, he did not make a nuisance of himself and gave Bai Yun plenty of space. When the time comes, he will demonstrate the persistence he needs to be a successful breeder.
Part of Gao’s success may be in his relaxed attitude prior to her peak of estrus: he is not bothering Bai Yun now, when she isn’t yet ready to mate. We manage our pandas in such a way that adults are not housed together except during breeding episodes. We believe that this mimics the natural situation as closely as possible. Gao Gao’s caution and reluctance to impose himself on Bai Yun may be heightened because, most of the year, he has no active relationship with her.
Our data suggests Bai Yun will peak later this week. When this occurs, we will be closing down the queue where she and Gao Gao reside. Guests to the San Diego Zoo can expect to see one of our younger pandas in the alternate “classroom” viewing area. Once her peak has passed and Gao Gao indicates that no further efforts on his part are necessary, we will reopen the main viewing areas to our guests. Bai Yun’s reproductive behavior may continue to be evident for several days after the fact. Stay tuned: it’s going to be a fun week!
Suzanne Hall is a senior research technician for San Diego Zoo’s Institute for Conservation Research