Pandas: Reading the Tea Leaves

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Things are falling into line in preparation for a possible panda birth this summer. Our camera system is squared away, other preparations are in place or are in final stages, and Bai Yun is being closely watched for signs of pregnancy. While there was a time when we could not easily discern what the signs she registered might mean, we have learned a lot over Bai Yun’s lifetime that helps us to better understand where she is at, reproductively speaking.

Ultrasounds started a few weeks back. The vets are looking for undeniable signs of pregnancy, like the appearance of a fetus. In past years, a fetus was first visualized 17 days before it was born. However, before seeing a fetus, there are other signs that indicate her body is getting ready for a pregnancy or a pseudopregnancy. These include the simple visualization of the uterus. It is usually difficult to see because of the gas in the gut and because outside of this season in her life the female’s reproductive tract is just less obvious. Hormones responsible for pregnancy and pseudopregnancy drive the enlargement of the uterus to make it more visible to our vets nearer to her birthing window. Thus far, there has been some indication of positive change of Bai Yun’s uterus.

Another indicator is her behavior. A significant marker to us is a decline in Bai Yun’s appetite for bamboo. She has begun showing this decline for the last few days, rejecting even her favorite species and leaving behind some fresh stems untouched. Her behavioral changes are also considered positive when she becomes sluggish and uncooperative, a change witnessed for the first time yesterday (July 14). Normally, a keeper might become frustrated by a bear that refuses to shift or won’t come when called or that generally seems noncompliant. This time of year, behavior of this sort from Bai Yun just makes us smile.

Is she pregnant? That we can’t answer with certainty yet. We can say that her body is getting ready and may already be gestating a fetus in its early stages of growth. Only time will tell us if this is not the dreaded pseudopregnancy we have seen with her before, in 1998 and other years we did not realize a cub. Perhaps due to her age we might expect her to be more inclined to have this false pregnancy this time around. On the other hand, Bai Yun is very healthy, at a good weight, and she has never missed with Gao Gao. So place your bets.

We’ll keep you posted as to her progress. In the meantime, back to reading her signs…

Suzanne Hall is a senior research technician for the San Diego Zoo’s Institute for Conservation Research.