panda weaning


Xiao Liwu: Weaning Wrap-up

Xiao LiwuLate last week, we separated Xiao Liwu from his mother for the last time. He remained in the main viewing exhibits for a few days while Bai Yun was shifted out of the area so that they were not across a door from one another. We have found in the past that in the first few days post-weaning, the cub can be quite vocal, calling for mother as it wanders about. This can arouse a response from Bai Yun; therefore, we find it best to put some distance between them to allow our adult female to remain relaxed.

As anticipated, our littlest bear has shown some tendency toward wandering and vocalizing in the last few days. This is normal. As mentioned in a previous post, the cub is always the one most unhappy about the separation and would prefer to prolong his or her relationship with momma bear. The lure of a constant companion, playmate, and milk source is strong! Her absence from the cub’s life is something the youngster clearly responds to. However, past cubs seem to move on from their discontent within about a week or so, and we expect Xiao Liwu will follow suit.

For her part, Bai Yun does not seem to reciprocate the sentiment that “absence makes the heart grow fonder.” Keepers have reported that she is doing very well post-separation. The only restlessness observed with her are those typical of food anticipation, the same bouts observed when the cub was with her daily. Otherwise, Bai Yun is very focused on priority number one: her bamboo and other food. For our matriarch, it’s business as usual. Her job of cub rearing now done, she appears thoroughly content.

Xiao Liwu has been shifted off exhibit to the upper bedroom area where he is closer to his keepers. This is beneficial to the little bear, as the keepers are poised to fill some of the social void left by his mother’s absence. Already, they have had nice sessions with him during which they have been able to hand-feed him apple slices and offer him back scratches. The apple slices are a small victory because, as you may recall, he has been unwilling to eat anything but bamboo to this point. Having a food source over which the keepers can bond with the youngster will enable them to build a stronger relationship. These bonding sessions become an important foundation for future training and husbandry that requires cooperation and mutual trust between keepers and animal.

While Xiao Liwu will be off exhibit for some time to facilitate his keeper-bonding experience, there is a silver lining for some of our panda fans. Patriarch Gao Gao has been shifted back to the main viewing area, where he will remain for the next few months. When you observe the bears, you may notice that both Gao Gao and Bai Yun have small shaved patches now, as both underwent routine veterinary check-ups at the end of last week. With that out of the way, and weaning complete, our panda facility will now settle into a new routine that will be the status quo for the near term.

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, Weaning Xiao Liwu: Leafy Greens.


Panda Yun Zi: On His Own

On Thursday, February 10, we completed the weaning process for Yun Zi. Keepers had considered putting him together with his mother for a few hours in the mid-morning, but the young bear had enjoyed a hearty breakfast and was sleeping it off all morning. Taking advantage of his peacefulness, the decision was made to forgo a reunion. When he awoke, Yun Zi was moved through the tunnels to the bedrooms in the upper area of the San Diego Zoo Giant Panda Research Station.

It was good timing. Overnight videotaping from the previous two evenings had revealed that mother and offspring experienced bouts of separation anxiety. They had spent some time interacting across the separation gate, no doubt a frustrating experience for both animals. It was time for us to change the situation to the benefit of both bears.

Yun Zi had done amazingly well through this process. I have witnessed the weaning of each of our five cubs, and it is my opinion that he handled it the best. He displayed very few signs of concern about the process until the end. Even when he did get restless, the intensity of his anxiety seemed lower than that of some of the other cubs. Yun Zi is a champ.

Is this a factor of our fine-tuned process? Or is it just a result of his mellow personality? Or could it be that he was taking his cues from his mother, Bai Yun? After all, she has been through this process many times before, and she probably recognizes the opportunity to wean when it arises. The literature on weaning in other species strongly suggests experienced mothers are more likely to wean early and show fewer signs of anxiety in the first days after weaning is accomplished. Although we do the best we can for our animals, it is my suspicion that Bai Yun played the biggest role in determining the outcome here.

Yun Zi is now in an area with only one camera available. You will get to see him on camera, from time to time, in the garden room. In addition to this space, which places him in close proximity to the keepers, he has the run of three sunrooms and a pair of bedrooms. He will be well pampered by the staff when he feels like interacting. Bai Yun, for her part, will have Gao Gao across the separation gate for now.  We will keep you updated as  changes occur.

Suzanne Hall is a senior research technician for the San Diego Zoo’s Office of Giant Panda Conservation.


A Tuesday at Pandas

The pandas were active at the San Diego Zoo on Tuesday, even though we had cloudy weather. Yun Zi was napping, as usual, but he was also bothering his mom, which isn’t too much of a surprise.  In the afternoon, the keepers cleaned  the exhibits and separated Mom and youngster, putting Yun Zi in one exhibit by himself.  He climbed up the tree, trying to look over in the other exhibit to see mother Bai Yun. He’s still getting used to being on his own.

Bai Yun did some roughhousing with him a couple of times but did not seem to chase him off as I had expected. Once Yun Zi was in the other enclosure, she settled down, sitting on top of the rock cave and chomping away on her bamboo for the rest of the afternoon. Yun Zi found a great hiding spot on top of the giant tree stump and took a very long nap.

Alyssa Medeiros is a panda narrator at the San Diego Zoo. Read her previous post, Christmas with the Pandas.

Here’s a panda growth chart comparing the five cubs we’ve had, provided by the San Diego Zoo’s Nutritional Services Department. Click to view in larger format.


Yun Zi Keeps Busy

For guests who come to the San Diego Zoo and really don’t know that much about giant pandas, it’s often strange to them that we would separate a female and her cub at such a relatively young age. But for those who have seen Bai Yun in the last month, they cannot deny that she’s been a little more agitated with the young male. I can’t really even say little bear anymore, because Yun Zi has grown at a wonderful speed, now weighing 97 pounds (44.1 kilograms).

As you’ve read from previous blog posts, the separation process is going extremely well. On Monday, for the first time in over a month, I saw the cub attempt to nurse from Bai Yun; it’s been a while since I’ve seen him get even remotely close to trying. Bai Yun quickly pushed the cub away, denying him any opportunity. She then began to roughhouse with him for about 10 minutes before rummaging through his bamboo again.

Nothing we’ve seen in the last week has led us to believe that Yun Zi is not ready for this next phase in his life. He has done an amazing job at keeping himself busy, and honestly, I think he looks forward to getting to eat all of his food without mother Bai Yun stealing the best pieces.

For us panda narrators, it s a treat to watch yet another of Bai Yun s cubs make this transition into solitary life. Since we are out there the entire time the San Diego Zoo is open (9 a.m. to 5 p.m.), we can help out keepers and the research team by keeping a close eye on the two to make sure that nothing gets out of hand when they roughhouse. If the cub were to show any signs of stress, we can inform the keepers. But Yun Zi is doing better than we could have imagined; he’s behaving like such a mature panda. As someone who helped take care of him when he was a baby, it’s a proud feeling to watch him now.

Anastasia Horning is a panda narrator at the San Diego Zoo. Read her previous post, Yun Zi: Calm and Mellow.


Clearly, Very Ready

Yun Zi: From cub to subadult

The weaning process continues at the San Diego Zoo’s Giant Panda Research Station. Things have gone very well for both bears thus far. Mother panda Bai Yun, in particular, is showing us that the time was most certainly right to begin separations. She has been more than adamant in rejecting most of Yun Zi’s attempts to nurse or play. That said, one nursing bout was observed early in the morning on Thursday, just before separation.

For his part, Yun Zi seems largely content during periods of separation. Keepers have noted that, if anything, his behavior appears a little more subdued than usual. Perhaps this is because he realizes that, for the first time, he is without his mother’s protection during the day. This might stimulate a desire to lay low, to avoid drawing attention to himself. This could be a response to the loss of the mother-cub bond; that loss is known to be more strongly felt by offspring than by mothers during and after the weaning process. Or perhaps this is a means of conserving energy on his part.

Last night, time-lapse video of panda Yun Zi was recorded to monitor his transition to the third step of the weaning process, an overnight separation lasting nearly 18 hours. Our youngster had a very good night, considering it was his first overnight separation. When the keepers said good-night to him, he was fast asleep atop the den in his exhibit, a resting place also favored by his father, Gao Gao, and older sister Su Lin. He remained at rest until after 3 a.m.

Interestingly, he got up briefly at that point to grab some bamboo and climb back atop the den to feed. He got hungry and didn’t look for Mom. Instead, he looked for bamboo, just like a sub-adult might do.

After feeding he went back to rest. Just before 5 a.m. he got up and began a bit of restless wandering in his exhibit. He did check the door between his exhibit and Bai Yun’s a few times. He climbed high in his structure and looked around. He went into his bedroom and waited at the door. And he seemed to notice when the keepers entered the facility at about 6 a.m.

His morning activity pattern, with the exception of the gate checks, looks very much like that of any other panda at the facility. It’s common for the bears to anticipate the arrival of the staff, knowing their breakfast will soon be served. Indeed, shortly after their arrival the keepers pulled both mother and offspring into their bedrooms to have their meals separately. This ensured that Yun Zi was getting a full belly without Bai Yun stealing his biscuits. Then the bears were reunited.

The first thing both bears did was move past one another to check and see if the other had left any breakfast behind.

Once given access to each other and the exhibits, the pair engaged in a rowdy play session lasting several minutes. No nursing attempts were seen. And then the bears went their separate ways, Yun Zi to his side for a nap, and Bai Yun to hers for some bamboo.

We have but a few days left of mother-son association, but we are very pleased with how well the two are doing with this process. I am struck by how completely Yun Zi has adopted the new exhibit space as his own. To my recollection none of our cubs has ever felt so totally at home there. Perhaps this is the reason for the very mild response we have seen in him thus far. Is his love of Gao Gao’s former abode the result of the exhibit renovations done a few months ago? It’s hard to say.

In any case, keep rooting for our boy as he moves from “cub” to “sub-adult.” He’s clearly very ready for it!

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, Moving Right Along.


A Panda New Year

Read what's in store for Yun Zi this year.

Best wishes to all for 2011. It’s a  new year at the San Diego Zoo’s Giant Panda Research Station, and with that comes the promise of many changes for each of our pandas.

Little Yun Zi is now nearly 90 pounds (40 kilograms), by far the largest of the sibling cubs at the age of nearly 17 months. He seems to be growing daily, thanks in no small part to his increasing skill at out-running his mother to get to the veggies and biscuits first. He still prefers the leafy bamboo, so there’s always plenty of that around, since Bai Yun prefers the culm to the leaves on most days, or so it appears.

As Yunnie increases in size and age, it’s becoming more apparent that the time for final weaning and separation is getting closer. (Panda cubs in the wild are weaned by 18 months of age; Yun Zi will be 18 months old on February 5.) We’re seeing more of the rough-and-tumble play and hearing more squeaks and little “barks” as Bai bites harder during these more frequent tussles between mother and cub. And Bai has been observed shoving Yunnie away as he attempts to nurse. This is all a crucial part of the training of a young cub by its mother, a process we’ve witnessed with her four times before. As harsh as it may appear, cubs are not injured and can often outrun Mom, out of reach or up a tree, to take a break. To our great delight, as aggressive as Bai Yun gets, Little Yunnie comes right back at her, time after time.  He’s learning his lessons well.

Yes, the end of this relationship is drawing near. We’re all waiting to see when and how this will unfold. Yunnie’s not the cub his brother was, who was not at all pleased by the separation, or sister Su Lin, who seemed most independent until she and Mom were given access to both sides of the viewing area and she then became a clinging vine, surprising us all. Yun Zi is very much his mother’s son, in size and disposition, mellow and self sufficient. Because of this, we are hoping that the separation process will go smoothly for both mother and cub and make for a truly happy New Year. Keep checking Panda Cam to catch a glimpse of this lively activity.

Ellie Rosenbaum is a panda narrator at the San Diego Zoo. Read her previous post, Panda Exhibit Renovation.

For information on how some of our previous cubs handled the weaning process, read about Zhen Zhen’s weaning, starting with Weaning Zhen Zhen: And So It Begins,  from January 26, 2009, and Su Lin’s, starting with Two’s a Crowd from January 28, 2007.


Weaning Panda Cubs

Before anyone reads the title of this blog post and panics: No, we are not ready to facilitate the weaning of Yun Zi from his mother!

Our littlest panda is just over a year of age. When he is closer to the traditional age of 18 months, we will aid Bai Yun in weaning her offspring, but I have seen in the comments of recent postings that there have been several questions about the separation process. Here I will attempt to respond to some of those inquiries.

Is Bai Yun weaning Yun Zi earlier than her other cubs?
This is an extremely difficult question to answer. The fact is, we don’t know with certainty how wild pandas wean their offspring. Is it a slow, gradual increase in separation time that culminates in a mother bear deciding not to reunite with her cub? Is it an abrupt end to an otherwise pleasant social pairing? Researchers have noted with other bear species that cubs have been driven off by males in order to mate with the mother. Another option is that mothers drive their cubs away on their own. Either way, parent-offspring conflict is a force in separating mother from offspring. In truth, wild panda weaning has not been documented. We do know that young pandas begin experiencing long absences by their mother at an early age. Bai Yun has certainly taken the opportunity to spend hours on end distant from Yun Zi, in the same way she has done with previous cubs.

Does Bai Yun refuse to nurse Yun Zi, and is this evidence of weaning?
In short: yes. Yun Zi does not nurse as frequently as he did when very young. This is a natural mammalian progression that changes due to the increasing capacity of the offspring’s stomach. However, at a year of age, Yun Zi has probably developed the teeth necessary to feed on bamboo (there hasn’t been a recent cub exam to say for sure), which means he can begin ingesting some of his routine calories from the plant that will become his staple. This is the beginning of the end of maternal dependence for Yun Zi. As he takes in more bamboo, his need for mother’s milk will diminish. Mind you, I said his need will diminish, but his desire for milk will not easily abate: hence, parent-offspring conflict. Human or bear, offspring typically want more of their mother than mother is willing to give.

What behaviors suggest Bai Yun is ready for weaning to occur?
Parent-offspring conflict takes many forms. In the past, Bai Yun will refuse nursing, or terminate bouts of nursing more frequently. She may become more aggressive about guarding her bamboo stash as she feeds or become rougher during play with her cub. But she will be prevented from putting real distance between herself and Yun Zi because she lives in a facility with barriers to her natural tendency to move about. Unlike her wild counterparts, she cannot simply walk away. This is why we must step in and facilitate weaning at the appropriate time.

For the mother panda, rearing of young is a balancing act. The female must weigh the costs and benefits of investing in her offspring. The benefits seem obvious to us: a healthy panda cub that grows and reproduces, passing on that mother’s genes to the next generation. The costs may be more subtle in our zoo setting, but they are still very real to Bai Yun: the energy required to gestate, birth, lactate, and rear offspring takes an enormous toll on the female body. At some point, the female needs to break free from the energetic demands of her youngster and reallocate her resources to ensure her own survival. Without doing so, she may not achieve her optimal reproductive fitness; that is to say, she may not succeed at having as many viable offspring—capable of having their own cubs—as she might otherwise. Protecting her own health and well-being is an investment in a mother’s future progeny.

As you watch the interplay between Bai Yun and Yun Zi over the coming months, keep in mind the conflict that is developing below the surface. Understand that there is no natural resolution to that conflict in a zoo setting without our involvement. If we don’t open and close a few doors, Bai Yun will be unable to fully reallocate her resources to her own personal well-being. And we all know the adage, “If Momma ain’t happy…”

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, SKRs Get TLC.

Watch video of our panda hearing study!


Weaning Zhen Zhen: Miss Independence

Yesterday, keepers closed the doors between Bai Yun and Zhen Zhen at the regular time of approximately 4 p.m. They passed an uneventful night, feeding and resting. This morning, when Zhen saw her keepers coming to pull her off for the morning cleaning of the exhibit, something new happened.

Keepers led her into the tunnel, and began talking with her and feeding her treats. She followed them happily through our tunnel system, stopping occasionally to sniff a spot here or there. Up top, she sat on the scale patiently as keepers weighed her (at 43.2 kilos). Then she walked into her new living space, the bedroom area into which she was born so many months ago.

As all pandas do, Zhen sniffed about her to reacquaint herself with the rooms. After finding a fresh stash of bamboo, she sat right down and munched happily. She paused occasionally, as she heard Gao Gao bleating nearby. He was registering his discontent. Where were his keepers? He was usually out in the yard by that time — what was taking them so long today? He, too, was in for a change.

After the lower exhibit had been prepped by the keepers, Gao was moved down from his top bedroom to the exhibit formerly occupied by Zhen. As he passed by in the tunnel, Zhen stopped eating and approached the door separating her from her father. Keepers could hear her sniffing loudly, inhaling his scent. For his part, Gao seemed unconcerned about his daughter’s presence, but was all about marking up the tunnel as he made his way to the public viewing areas. It’s all mine, he seemed to be saying.

Zhen returned to her bamboo. She spent some time investigating her enrichment, a cinnamon-coated hanging ball, placed in her grass-laden garden room. She searched for biscuits. She sat still and listened, taking in her surroundings. She rested and she climbed. All in all, she entered into her independent life surprisingly well.

We expect that as the day wears on she might beg for some of the keeper’s attention — and they stand at the ready. Already she has had a few extra biscuits, and keepers are stopping in regularly to check on her. Even so, the general consensus is that, compared to big sister Su Lin, Zhen is handling this exceptionally well.

So far so good with Bai Yun. If she experiences any engorgement of her mammary glands due to Zhen’s abundant comfort-nursing over the last few weeks, Bai might have some discomfort for about a day or so. Soon thereafter, she will likely be showing us how content she is to be on her own, too. Thus far she has done beautifully with our separation protocol, and we are pleased to see her faring so well.

For the next few days, look for Zhen on cameras 11, 15 and 17. She may head out to the classroom exhibit in a day or so, on cameras 27-29. Gao, for his part, can be observed on cameras 1-3 for the foreseeable future, and Su Lin will be on cams 30 and 32. Bai Yun’s exhibit and cameras will remain the same.

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


Getting Closer to that Time

All waited anxiously for the steel door to open Wednesday morning between a sleeping Zhen Zhen and a sleeping Bai Yun. How long would it take before they reunited? Who would instigate the reunion? Would there be a mad dash to the doorway?

Finally the door opened and…nothing happened. It was a surprise to me that it took vocalizations from Bai Yun, who wandered over after a few minutes, and a full 45 minutes for ZZ to bother coming out of her tree. Mom coaxed her over to the pile of pine shavings thoughtfully provided by the keepers for a romp and a short nursing bout, but then things changed.

Was it a teaching/learning session, with Mom biting and holding Zhen down? It seemed so and could have been rough play. Or it could be that, as the separation time increases, Bai’s tolerance is diminishing? She was pushing the cub off a log, biting her on her hind leg hard enough to provoke vocalizations, and sitting on the cub as the cub would sit on Mom. Back and forth it fluxed between cuddling play and rough play, so it’s hard to tell exactly what is going on.

It’s a challenging time for both mother and cub, and we’re all watching with interest as this separation process continues.

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


Weaning Zhen Zhen: Step 3

Monday morning, February 16, was the first morning we lengthened the separation time for giant pandas Bai Yun and Zhen Zhen to approximately 18 hours. We separated the bears about 4 p.m. Sunday, February 15, as has been the case for more than a week. However, on Monday we waited to reunite the two bears until about 10:15 a.m. Zhen has been used to seeing her mother again early in the morning, and the change dawned on her slowly yesterday.

Initially she was nonplussed and spent the early morning hours feeding on bamboo and playing with three Boomer balls the keeper had placed in her exhibit. At about 8:30 a.m., when the hearing study training began with Bai Yun, Zhen heard the clinking of gates and the voices of keepers talking with Bai during her session. It must have suddenly occurred to her, “Hey, I am usually with momma before this happens,” and she began to try to peek down the corridor and wait at her keeper door for access. But it wasn’t time yet.

The falling rain did not deter Zhen from slow motoring about her exhibit, checking her doors repeatedly and sitting patiently atop her den or near the corridor. More clinking gates signaled that Bai Yun had now been released into the exhibit next door, and still the gate had not opened. Slowly, Zhen started getting more wound up, moving faster about her exhibit, climbing and generally foregoing the chance to rest.

Bai Yun, however, showed no sign of concern. On exhibit, she happily munched bamboo, never once checked the separation gate, and barely paused at any point in the morning to look about her. In fact, staff reported she had one of her best-ever training sessions that morning: clearly she is not losing sleep about the separation from Zhen.

Once reunited, Zhen mugged her mother. Within a few minutes of the introduction, Bai Yun relented to the gales of Hurricane Zhen and led her into the den, out of the rain, for a nursing bout. Satiated and satisfied with her mommy time, Zhen then climbed a tree and slept on her own for a period.

We anticipated that this step in the weaning process would be one of the most difficult for our littlest panda. Her siblings also started to really feel growing pains at this stage, and so we knew Zhen would likely follow suit. But the real key to all of this is Bai Yun.

As I mentioned in previous blogs, we don’t know for certain how the weaning process is achieved in the wild. We believe it to be a largely mother-driven endeavor, with mom either wandering off, denning up, or driving her cub away at some point. One thing we can say for sure: it doesn’t matter if Zhen is 8 months or 18 months or 28 months, she wouldn’t leave her mother if it were up to her. This is why we expect some discomfort from her during the weaning process. But Bai Yun is a different story. When she shows us she is relaxed and taking this all in stride, then she is telling us SHE is ready. In the wild, she would be content with taking the steps necessary to separate from her youngster. And this is our barometer that the timing is right.

I have read several of your comments on the blogs in recent weeks and know that many of you have expressed sadness over the weaning. Like you, I feel a little for Zhen when I see her appearing anxious. As a staff, our concern over her well-being is one driving force behind our intensive effort at this time: we are monitoring her closely, watching both Bai and Zhen overnight with videotape, assessing their reactions on a daily basis. Keepers are ensuring Zhen has access to high-quality bamboo, enrichment items, and their attention. But we recognize that there is no way around Zhen feeling a little confused during this time.

However, Barometer Bai Yun informs us that we are moving forward in the right way and at a pace that is comfortable…for HER. As a mother myself, I understand the sense of relief when a youngster moves on, grows up, takes the next step. Bai Yun’s current demonstration that she is content is an important indicator that we should all factor into the equation.

Some of you have asked about comparisons to Wolong cubs and their sociality post-weaning. In Wolong, cubs are weaned very early, at about six months of age. They are then placed in groups with other youngsters to fulfill their social needs, a very smart way to handle motherless youngsters. Zhen, like our other cubs, has been with her mother a full year longer than those Wolong cubs and is better able to adapt to a life on her own as a result.

We recognize, however, that subadult pandas can be more social than adults. In the wild, young male bears can be found in proximity to older males, a type of social shadow that the older male does not feel threatened by. Even the young subadults seen in trees at mating sites may be drawn there by the ruckus of a female in estrus and her entourage of males. We try to offer social opportunities to our subadults in the form of increased keeper interactions, training sessions, and howdy gate opportunities when possible. To that end, Su Lin and Zhen may one day meet across a gate. It’s also the case that our littlest independent pandas often seem drawn to the public viewing areas, enjoying the daily litany of admiring guests who come to see them. We will accommodate this inclination as well, when the time is right.

Zhen will soon be pulled off exhibit, when we are ready to make the separation between mom and cub final. For a time she will live behind the scenes, soaking up keeper love and residing far enough away from mom that it will not be a tease to her that mom is in proximity. Enjoy these last few days of the two together, and celebrate that she will soon be on her way to adulthood. Like Su Lin and her other siblings before her, Zhen will be well cared for as she makes this important transition.

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