panda breeding season


Big Guy on the Block

Gao Gao is fueling up for breeding season. Little does he know....

Gao Gao is fueling up for breeding season. Little does he know….

As some San Diego Zoo guests are finding out, Gao Gao is the only panda out for viewing in the main exhibit currently (Bai Yun and her cub, Xiao Liwu continue to charm guests in the north exhibit until noon each day). As construction workers continue building Yun Zi’s artificial tree (which looks great so far!), Gao Gao has been entertaining us with his usual eating and sleeping, and a little extra movement right now.

Many of you know that Bai Yun would typically begin showing some hormonal behaviors as early as March for breeding season, and Gao Gao is letting us know that he is ready. He is currently eating more and gaining weight to show off to that gorgeous female he sees once a year. Of course he will not be breeding this year as Bai Yun is with a cub and not cycling. So the big question everyone’s been asking lately is, “What will Gao Gao do?” This year Gao Gao will just have to cope, and soon he’ll realize that he doesn’t smell a female in estrus.

As for next year’s breeding opportunities, we can’t say. To the best of our knowledge there hasn’t been a female panda to give birth over the age of 21, and Bai Yun will be 22 this coming September. We have observed an older male, Shi Shi, but watching a female for her entire breeding life has taught us so much about what is normal for Bai Yun. She is, after all, a big part of Gao Gao’s success as a breeding male—she is responsive and an amazing mother to her offspring.

Come see us soon, but do not be upset if you see Yun Zi off exhibit as his tree is being constructed!

Anastasia Horning is a panda narrator at the San Diego Zoo. Read her previous post, Pandas: The Big Boys.


Love is in the Air

Gao Gao investigates Bai Yun's scent.

Today marked the first day of “pen swapping” for Bai Yun and Gao Gao.  Pen swapping simply means that we put Gao Gao in Bai Yun’s exhibit, and Bai Yun in Gao Gao’s exhibit.  This simple exchange tells us a lot about where Bai Yun is in her estrus cycle and how interested Gao Gao is in Bai Yun.  After observing both of them quietly explore, olfactory investigate, and scent mark, it is clear that love is in the air, but we’re not quite there yet!

Giant pandas are solitary in the wild, and the coordination of courtship and breeding is dependent on communication at a distance via the exchange of olfactory (scent) and acoustic (vocalizations) cues between males and females. Over the years, researchers from the San Diego Zoo Institute for Conservation Research have documented the specific information conveyed by both scent and vocal signals, and we now know that pandas can determine the age, sex, and reproductive status of other giant pandas through these signals.

Scent is the primary form of communication during the early phase of estrus. It serves to advertise the identity of giant pandas prior to any face-to-face meetings.  Through the inspection of  scent marks left on trees, rocks, and the ground, pandas can assess other individuals and determine whether or not to follow these “scent trails” and pursue courtship. Our observations of Bai Yun have shown that scent marking typically reaches its peak of expression about 3 to 5 days prior to ovulation.  In the wild, this peak in scent marking would coincide with a relative convergence of male and female pandas and presages a switch to the vocal signals that characterize courtship communication during the face-to-face encounters that are typical during the two- to three-day period that the female is receptive to breeding.

Over the years, we have fine-tuned our management of the panda breeding season.  We use a number of techniques to assess Bai Yun’s estrus status, and Gao Gao’s interest in Bai Yun, as well as his motivation to breed. Pen swapping remains one of our most informative, and simple techniques, providing much insight and potentially priming both bears for what (we hope) is just around the corner.

Megan Owen is a conservation program specialist at the San Diego Zoo Institute for Conservation Research.


How Well Do You Know Your Pandas?

Gao Gao

Gao Gao

We will be putting you to the test over the next few weeks. Our pandas will be moving about the San Diego Zoo’s Giant Panda Research Station every few days, and which bear is on which camera will change each time they move. It’s unlikely our intrepid moderator will be able to keep up with all of the rapid changes, so you will have to use your panda identification skills to help figure out which of our black-and-white bears you are currently seeing on the Panda Cam.

Why are we playing round robin with the pandas? It’s because our new bamboo cooler is ready for installation. Thanks to the generous support of you, our panda fans, our urgent plea for funding for a new bamboo cooler was answered. But there is still a lot of work to be done before the pandas can enjoy fresh bamboo straight out of the new cooler you provided for them.

A replacement cooler has been selected, and it’s time to prepare the site where the bamboo chiller will live. This involves many steps, including removal of the old coolers, demolition of the concrete in the area in order to prepare a new foundation for the new cooler, running the utilities to just the right spot, etc. Some of this work involves the use of equipment such as jackhammers, so during the loud portions of the process we will be moving Bai Yun and Gao Gao away from the noise source.

Bai and Gao will make their first move to the classroom area on Monday morning. The regular viewing area will be closed, since there won’t be any bears in that area anyway. Zoo guests will be able to view one of our adult bears in the classroom, and Su Lin and Zhen will be ensconced in their bedroom/garden room area. It will be a bit cozy in the top portion of our facility for a few days, but we feel this is in the best interest of all the animals so as to remove them from the vicinity of any potential stressors. Once the loud portion of this phase of work is complete, Bai and Gao will probably return to their regular exhibit spaces.

Once the site is ready to accept the new cooler, we will be ready to crane the unit into the facility. This should happen around the end of the month. It might necessitate another move to the classroom for our adult bears, but they are troopers who will be fine with this stimulation. Both of them have spent plenty of time in those areas over the years, and taking a few days’ hiatus from the lower areas should work out fine…

…unless, of course, Bai Yun says otherwise. If she shows any signs of estrus whatsoever—and we are monitoring hormones in order to get as early a warning sign as possible—the whole project puts on the breaks and waits. Once again, Momma bear rules.
Thanks again to everyone who helped us make this new cooler a reality. Soon, the bears will be benefiting from your generosity directly. In the meantime, have fun playing panda roulette!

Suzanne Hall is a senior research technician for San Diego Zoo Conservation Research.


It Is Up to Bai Yun

Now that Zhen Zhen is weaned and separated from her mother, the focus at the San Diego Zoo’s Giant Panda Research Station has moved to Bai Yun and a possible estrus. Bai and Gao Gao have each been up to the hospital for their annual check-ups and pronounced fit and healthy. You may have noticed the shaved patches on their bodies; this is done to facilitate routine blood sampling and, for Bai Yun, the regular ultrasounds of her abdomen that might confirm possible pregnancies down the road. Bai is being checked regularly to see if and when an estrus is progressing. These are early days yet, but the signs are promising.

We’re all very much aware, however, that at 17 years old, Bai is an older panda and we remember how unusual (compared to her past cycles) and unpredictable her last estrus was. It’s a time for watching and waiting for changes large and small. Even after all these years, the pandas can still surprise us, so “We don’t know” is a common response—because we don’t know! As always, it’s all up to Bai Yun.

Gao Gao, meanwhile, has been getting ready in his own unique way, with leg-cock urination, scent-marking, and lots of bleating. It’s pretty apparent that he knows that spring is coming and as Bai Yun becomes more receptive, the door will be opened and the careful, protected introduction in the “howdy” area will begin. When this occurs, as with everything else, depends on Bai, so don’t be surprised by anything you see on Panda Cam.

Zhen Zhen seems to be settling in nicely. Checking on her yesterday morning, it was like watching her mother as she sat and methodically munched bamboo. The keepers have said that she still occasionally looks for her mom, but this is to be expected and is consistent with the behavior of her older siblings at the same stage of life. Su Lin is housed next door, and she has been treated to a new climbing structure, where she’s been seen perching during the day for naps.

As if that was not enough, the long-awaited bamboo cooler is on the way and preparations are moving forward to remove the old chillers and make space for the new. Many thanks to those of you who have helped make this possible. Our very particular pandas will, I’m sure, be most satisfied with their lovely, fresh bamboo selection.

Ellie Rosenbaum is a panda narrator at the San Diego Zoo.


Watching Bai Yun

Zhen Zhen has been doing an amazing job of adapting to her new life on her own, so far. Bai Yun has also been doing a wonderful job of getting back into the swing of things. Last week she and Gao Gao both had their spring physicals. Bai Yun has been eating and resting, as she may be coming into her estrus in the near future.

Now that it’s March, we will be watching for signs of any hormonal change and observing her behavior closely. Bai Yun and Gao Gao are currently spending their days in the front viewing area, so guests may be able to see some great behavior. As Bai Yun gets closer to a possible estrus, she will be eating more daily and might be scent marking quite a bit as well. Females in the wild have a home range of about one square mile, and as they come into heat they will scent mark their home range, letting neighboring males know that it’s again that time of year. The same goes for Bai Yun’s exhibit and her neighbor, Gao Gao, who has always been very good about responding.

When the pandas get into the swing of spring, the keepers will be switching Bai and Gao Gao’s exhibits. This way each will smell the presence of the other. Bai Yun will find scents of a male that she is familiar with, and Gao Gao will smell a female that might soon be ready to mate. To prepare for mating season, Gao Gao might put some more weight on. Weighing in at 175 pounds, he is a lot smaller than most males; but however small Gao Gao is, he is currently the only successfull naturally breeding male panda in the United States.

Anastasia Horning is a panda narrator at the San Diego Zoo.