Getting to Know You, Again

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Bai Yun's not interested in food these days!

Giant panda Bai Yun continues to march through estrus. Her rate of scent marking has increased from its baseline of roughly .08 bouts per hour to a whopping 43 bouts per hour this morning. She is walking through water quite a bit, a behavior that likely aids in scent dispersal, as her drippy fur leaves a trail of wet odor while she motors about. She continues to ignore her bamboo and even spit yams back at the keepers during a hearing study trial today. She’s fussy, and squirmy, and acting totally normal for a female in estrus.

On the physiological front, she has also given signs of her status. Her genitalia have enlarged in size and changed color. Swabs of her reproductive tract indicate that its composition of cells is changing in a manner consistent with an approaching breeding window. We are running hormone samples when we can get them, but so far today Bai Yun hasn’t given us enough urine to submit something to our lab.

We were thinking we might need to open the howdy gate between our adults in a few days, in anticipation of a breeding window. However, this morning Bai Yun could hear Gao Gao bleating on the other side of the wall between them. She was very attentive to his calls, and she even bleated back several times. It’s unusual for her to be bleating already, her “advertising stage,” remember? She should be silently marking. But no, she was clearly telling us this morning that she was ready to get reacquainted with her mate.

In response, this afternoon we opened the howdy gate for visual access. Gao Gao, as anticipated, was happy to check out the view, and several times he quietly approached while Bai Yun was nearby. For her part, our matriarch sat in close proximity to the gate for the better part of half an hour. She sent him mixed signals: a chirp (which says “come hither”) followed by a bark (which means “stay away”). Sometimes she sat still looking at him; sometimes, she charged the gate. Back and forth she went between the vocalizations. When she chirped, Gao Gao would stay close, sniffing at her and the gate. When she barked, he would leave, but only for a little while. He knows not to be gone too long.

In the coming days, Bai Yun’s barks and ambivalence will give way to more solicitous behavior. Gao Gao will help us keep track of her change of status with his behavior. Follow along on the Panda Cam, and see if you can see that change yourself. We’re looking for rear-present, tail-up behavior on her part. With him, we are looking for a consistent presence at the gate, even pulling at the gate when she is near. When she starts backing into that gate with her tail raised, you’ll know it’s time.

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, Who You Calling Old?