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panda birth watch

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Pandas: Getting Closer

Bai Yun continues to progress toward her birthing window in a predictable fashion. Part of this progress means she is “denning up” in preparation for the birth. Over time, she is spending more and more time in the den resting, eating, and nest building inside. In the last 24 hours, she spent 680 minutes (over 11 hours) in that den, but soon enough it will be 1,440 minutes (a full day!).

For now, when she is not in the den, she can typically be found sleeping just outside the den entrance. She no longer makes trips out to the large outdoor space she had available, so the keepers have closed off that area. She has even stopped visiting the garden room and resting atop the platform there. From this point forward, it’s den, bedroom, and sun room…but increasingly just den.

We can’t tell you exactly when Bai Yun will give birth. We can say that all signs point to early August. Our various signs and indicators do have some predictive value for us: How far out did she reduce her bamboo intake? When did she begin spending time in the den? What do the fetal measurements tell us about how developed the cub is? I can tell you that all of these factors are aligning nicely with regard to a predicted birth date, all pointing to windows within a few days of each other. There is enough variability, however, that we won’t be brash enough to predict for you exactly when the cub will be born. You could say we are watching her overnight…

Cub, not cubs. Did I mean to type that? We have good evidence that one cub (gestating in the right uterine horn) is developing beautifully. You may have seen it on the ultrasound pictures, curling its head and moving its paws. The vets have been able to see mineralization of the bones and tiny claws. This cub looks strong and healthy so far. What about its twin?

Last week we saw a heartbeat from the cub in the left uterine horn. It looked smaller and less developed than its sibling. Since that heartbeat sighting, we haven’t had a chance to see Left Cub. We have not seen its heartbeat stop or its placenta degrade as Mei Sheng’s uterine roommate did in 2003. But staff is becoming increasingly suspicious that Left Cub will not survive the pregnancy.

If this makes you unhappy, you’ll have to take it up with Bai Yun. This is her call. But you’ll have to wait for some time, because it looks like she’s going to be busy for the next few months!

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

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Denning Up

The birthing den Bai Yun has used for all four of her cubs thus far is usually kept closed. Most of the time, it sits idle and bear-less, because offering a panda access to the den at the wrong time seems to ensure it will be used for the wrong reasons. In the past, if the den was opened beyond the time that Bai Yun needed it, or if alternate dens had been provided for her to choose from, she typically started using the space as a latrine.

Last week, as part of the normal progression of preparations for a potential panda birth, we opened the birthing den for Bai Yun. She now has access to it 24/7. On her first night, she visited the den, dragged some bamboo in, and began to make her nest. In days since, the nest has built up, and she has been seen resting inside. Most of the time, however, she can still be found resting in her adjacent rooms.

A few days before a birth, a pregnant female will begin to den up in earnest, spending considerable amounts of time inside her den. When awake, she will continue to work on her nest, dragging in bamboo and feeding inside, stripping culm and dropping fragments to the floor that will contribute to the substrate her cub will rest on. In the past, I have had a chance to examine Bai Yun’s nests, and I am always struck by the smell of it: even after weeks of living inside with a cub, the den smells fresh and earthy, fragrant with bamboo odor. Bai Yun certainly works hard at creating and maintaining her birthing space.

Our best estimates point to an early August birth, if Bai Yun is indeed pregnant. We continue to see positive signs both from her behavior and from ultrasounds that indicate this is probably a pregnancy, though we have not yet seen a fetus. Watch for signs from Bai Yun that her time is getting closer and see if you can predict her birthing window.

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

Moderator’s note: We will be celebrating Su Lin and Zhen Zhen’s birthdays on Monday, August 3, with a big ice cake served in the morning and a smaller cake in the afternoon.

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Pandas: Reading the Tea Leaves

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.