panda research


Panda Den Cam

Give us a peek, Bai Yun!

While Bai Yun and her one-day old cub are snuggled up in the birthing den at the San Diego Zoo’s Giant Panda Research Station, we are getting ready to share this incredible experience with the world. At 2 p.m PT today, the den cam will go live!

It is exciting to think about how many people around the world will be watching Bai Yun’s every move in the den and every developmental milestone the cub experiences. Although this is Bai Yun’s sixth cub, this incredible process is just as exciting to watch as it was back in 1999, when Bai Yun had her first cub, Hua Mei. Back in 1999, we had the den cameras set up as a way for researchers, keepers, and veterinarians to keep tabs on Bai Yun’s pregnancy, birth, and early postpartum period. Back then, we all gathered in the keeper kitchen and watched Bai Yun’s every move via several small video monitors. The video was all recorded on VHS tapes (which we still have, of course!), and we were able leave Bai Yun in peace while we took advantage of this window on Bai Yun and Hua Mei’s private world inside the den. It was, and still is, truly magical to watch.

Our video system has changed a bit over the years and, importantly, we can share this magical experience with the world. Enjoy the view!

Megan Owen is a conservation program manager for the San Diego Zoo Institute for Conservation Research. Read her previous post, Panda Cub #6.


Panda Enrichment

Yun Zi

The Giant Panda Research Center was full of activity yesterday, November 1. Yun Zi was being very entertaining for our guests, especially with his enrichment. Our keepers gave him a pile of soil and shavings sprinkled with scent. He gave our guests a show by rolling all around in the soil, rubbing it on top of his head. It was like a kid rolling around in the sand on the beach. Once he was finished, he looked more like a small black bear than a giant panda. He was a day late for Halloween!

Bai Yun seemed very content. At one point she sat on top of some branches while resting her head on the tiny hammock that is attached to her tree. She just looked so silly! And at the end of the day, while Bai Yun was in her pond and Yun Zi in his hammock, both sat happily eating their dinner.

Alyssa Medeiros is a panda narrator at the San Diego Zoo. Read her previous post, Pandas: A Beautiful Day.


Panda Pregnancy: Pseudopregnancy

Why is pregnancy in pandas such a complex affair? On Friday, we reviewed embryonic diapause as a factor in adjusting the length of panda pregnancies (see post Panda Pregnancy: Embryonic Diapause), and today I’ll describe another interesting aspect of their reproductive strategy: pseudopregnancy.

First, a definition: what is pseudopregnancy? Sometimes known as a “false pregnancy,” a pseudopregnancy occurs when a female exhibits the signs and symptoms of pregnancy when in fact she is not experiencing one. Like embryonic diapause, pseudopregnancy is not a phenomenon limited to pandas; it has been observed in mice, dogs, and even humans.

In pandas, the signs and symptoms of pregnancy that also occur in a pseudopregnancy include a decrease in appetite, a decrease in activity level, and even physiological changes to the genitalia. The onset of these changes in a pregnant female follow the rise in progesterone noted after the period of embryonic diapause, when the blastocyst implants in the uterus. But here is where it gets tricky: pseudopregnant females also experience a rise in progestins. It is what is driving their behavioral changes, too.

In many animals, the way to detect pregnancy is to look for the presence of progestin byproducts in the urine, feces, or blood. In a panda, if you find progestins in the urine of a female you can only say definitively that she is either pregnant or pseudopregnant. So far, we haven’t been able to identify a way with progestins to tell for sure if she is gestating a fetus.

Over the years, panda researchers have puzzled over this. What is really going on here? Is it possible that pseudopregnant females were actually bears that had, indeed, gotten pregnant but miscarried before the birth? That is certainly possible, and Bai Yun has shown us via ultrasound that she has three times carried twins only to give birth to a singleton. Clearly there is fetal death occurring in utero from time to time. It is entirely possible that many “false” pregnancies would retrospectively be classified this way, had ultrasound technology been more available in the past.

However, it is also true that in some cases, pseudopregnancy has been noted in females who had not even had the chance to breed. Thus, for those females, there was no possibility of a pregnancy (or miscarriage), and they went through the behavioral motions anyway.

Why would a female panda experience the signs and symptoms of pregnancy even if she didn’t give birth? We aren’t entirely certain, but here is one theory: because it doesn’t cost them much to do so. From an energetic perspective, it doesn’t take much effort to slow down and allow your body to become physiologically primed to gestate a panda fetus. Cubs only grow for about 50 days, which doesn’t require a long-term commitment. And if you are a panda, which only mates once every two to three years while raising a single cub in between, it is important to have that pregnancy “take.” If you miss a year, it’s a big loss to your lifetime reproductive output. When the typical lifespan of a wild panda is no more than 20 years, and a female isn’t fertile until at least 5 years of age, she can only rear about a half dozen cubs in her lifetime. Losing one has a big impact on her overall reproductive success. In the end, it could be as simple as a little cost-benefit math equation: pandas can’t afford to lose the chance to reproduce, and it doesn’t cost them much to be prepared.

Embryonic diapause makes it difficult to assess when we should expect a birth in the time shortly after breeding. Pseudopregnancy insures that we must interpret our progesterone and behavioral indicators with caution. How, then, do we actually confirm a pregnancy in pandas? I’m sure you have some idea, but there is also some new and exciting research on that front. That will be the topic for my next entry. Stay tuned!

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


The Waiting Game

Bai Yun

In pandas, the period of fertility for females typically occurs in spring. Bai Yun routinely experiences her estrus in spring, and all of her breeding dates for those years she has given birth are lumped into a 33-day window beginning in late March. A betting person would have put money on March-April for this year’s estrus, as well. We are nearly all the way through March at this point. Bai Yun, for her part, has shown very little indication that a breeding date is near. Changes in the size and color of her external genitalia indicate that she is in the early stages of estrus, but we may yet be a few weeks away.

We do not yet have any way to know if she will have a fully expressed, fertile estrus in 2011. Some pandas experience weak estruses, in which the behavioral signs are muted or the hormone profiles are not quite as dramatic as those that have strong estruses. These weak profilers typically don’t succeed in getting pregnant. It is probable that they don’t quite get to the point of ovulation. Young females experiencing their first estrus often show weak profiles, but as they mature, their behavioral changes grow stronger. Some older females also experience these weak profiles, presumably as their aging bodies senesce and they put their reproductive days behind them. Thus far, Bai Yun has never had such a weak estrus, although she has had a truncated behavioral estrus in 2007 and 2009. Due to this change in pattern over her last two fertility windows, we anticipate another truncated estrus from Bai Yun this year. She’s very healthy for her age, but it is possible that she could have a weak estrus, or even no estrus at all. Only time will tell what this breeding season has in store for her.

Fortunately, Gao Gao is also very healthy and is clearly responding positively to the season. His changes in genitalia and behavior are right on track, and he has been seen climbing high in his exhibit and wandering about in a manner consistent with a male hoping to cross paths with an estrus female. If Bai Yun is willing, Gao Gao will be ready. We’ll just have to wait and see.

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


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.


Panda Pregnancies 101

Our director of our Reproductive Physiology Division has provided some more answers to questions regarding panda pregnancies.

We are so pleased to learn of the birth of Zoo Atlanta’s newest panda cub. The 3-D pictures of Lun Lun’s cub in utero certainly were amazing. This advanced imaging is normally used in humans to detect skeletal and cardiovascular defects, but has become popular among human parents-to-be for getting a “sneak peek” at what their baby may look like at birth. Should our own Bai Yun become pregnant again, it is possible that we will also invite a local expert to help us obtain 3-D images of a cub (or cubs), as we do not currently own equipment that allows us to capture these images.  In our case, 3-D imaging would not replace our routine 2-D ultrasound scanning to monitor the growth of Bai Yun’s fetus(es).

In addition to the standard tests our veterinarians and researchers would run to monitor Bai Yun’s health and pregnancy status after breeding, we will certainly measure her ceruloplasmin levels. This protein may give us information about the presence of a fetus before our standard tests are able to detect a pregnancy.

We have seen with thermal imaging and ultrasound that many giant panda pregnancies are lost during gestation. There are a few reasons that a fetus might be reabsorbed. Fetal defect or death, uterine disease, maternal disease, or hormonal disruption of a pregnancy could all cause a fetus to be reabsorbed. This phenomenon is widely reported in mammals, including humans. During the process of reabsorption, the fetus breaks down in the uterus and through natural processes is eliminated. In Bai Yun’s pregnancies, when a twin died our veterinarians did a follow-up ultrasound to verify that no fetal tissues remained in the uterus.

Our vets and animal care staff continually monitor Bai Yun’s health, so we can rule out maternal or uterine disease as a factor in fetal resorption. In our endocrine lab we monitor Bai Yun’s hormone levels and know that there were no deviations from the normal pregnancy profile. With ultrasound we have been able to see fetuses begin to break down and sometimes disappear completely. But the exact cause of fetal death in giant pandas is still a mystery. Through our work with ultrasound and thermal imaging, we suspect that Bai Yun routinely conceives multiple fetuses, then reduces that number to one through a process called “prenatal litter pruning.” Because it is very rare that a giant panda mother raises more than one cub, there may be a mechanism within the uterus that reduces a multiple pregnancy to a singleton before birth about 50 percent of the time.

There is no evidence that twinning is more common following artificial insemination (AI). With our own Bai Yun, we know she was pregnant with twins (or even triplets in one case) following natural breeding.  The fact that she gave birth to a single offspring was not related to the method of insemination (artificial or natural). Some giant panda researcher believe that artificial insemination following natural breeding will increase the incidence of twins, but there are no data to support this belief. Regardless of our ever-improving AI techniques and timing, it is not a substitute for natural breeding! The male giant panda always knows the right time for insemination, and fresh, unprocessed sperm is always the most fertile.

Barbara Durrant is the director of the Reproductive Physiology Division at the San Diego Zoo Institute for Conservation Research. Read her previous post, Panda Pregnancy Tests.


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!


A Bittersweet Time

Zhen Zhen

As preparations continue for Su Lin and Zhen Zhen’s move to their ancestral homeland, there’s a lot going on at the San Diego Zoo Giant Panda Research Station. The girls’ last official exhibit day was August 16, which means our priority for them right now is training and research rather than exhibit time. Guests on August 17 were able to get a look at them—or not—depending on when they stopped by, and this situation could change to “off exhibit” at any time. We have no date as yet for the actual move; as always, we’ll let you know when it happens.

What is all this training and research? Previous bloggers have addressed this, but in brief, the training is designed to minimize the stress and increase familiarity with the travel crates. Our previous pandas have moved surprisingly well with this kind of training—after all, they have their biscuits, bamboo, and friendly faces with them. Aside from a comfy place to nap, what more could they ask for? While the bears fly cargo, they always go escorted by someone they know who checks on them on a nearly hourly basis. For Mei Sheng, the trip to Wolong took about 21 hours, all in; I believe it’s a bit less to Bi Feng Xia. Getting cozy in their crates means that they have to spend time in them, hence the time now spent “off exhibit.”

Then there’s the issue of diet. Anyone who’s traveled, whether domestically or abroad, can relate to the fact that food is different wherever you go—it’s one of the things that makes travel so interesting, although it can be a challenge. The girls are transitioning to the steamed bamboo bread that they’ll be receiving in China, in addition to all the fresh bamboo they can eat, and the keepers report that the diet transition going well. This, too, is to minimize the “strange” in their new home.

And the research? There is hearing study data to continue to collect while we can, records to update, and videos to make to document training and husbandry procedures here so that their Chinese keepers will be better able to understand their precious charges and minimize the “language barrier” of new behaviors on both the part of the keepers and these new, unfamiliar bears.

In the past, we’ve had panda cubs remain here longer than three years, but it has always been part of our research agreement that the Chinese may move the bears after their third birthdays. It has been our good fortune to have Hua Mei, Mei Sheng, and Su Lin stay longer, but Zhen Zhen’s journey at just three years old is good fortune in its own way. It is difficult to introduce adult pandas to one another outside of breeding season, but subadults like ZZ can be found interacting in the wild, as well as in managed care, until maturity. None of our previous cubs have had this opportunity, since they were always larger and older, but perhaps ZZ can be introduced to playmates over the next year or so. Should this happen, she’ll have had a different experience than our previous cubs. This in itself offers yet another opportunity to learn about the development of young pandas, adding another important piece to the puzzle of the panda.

Ellie Rosenbaum is a panda narrator at the San Diego Zoo. Read her previous post, Panda Days of Summer.


One More Thing Before They Go

Su Lin

For the past year, Su Lin has been the primary subject of our giant panda hearing study. About six months ago, Zhen Zhen began her participation in earnest, and for the last two months, she has been showing us what a three-year-old panda can hear. Data that we’ve collected from both of these bears are unprecedented and mark the first glimpse into the auditory world of the giant panda.

While keepers are working hard to make sure Su Lin and Zhen Zhen are ready for their upcoming adventure and transition to life at the Bi Feng Xia base in Sichuan, China, our research team is also working hard collecting every last scrap of data we can on this pair! Our hearing study requires a collaborative effort between researchers, keepers, and bears, and very few other facilities anywhere in the world have the combination of resources that allows the pursuit of such research. We are very proud of our collaborative efforts and are going to miss working so closely with Su Lin and Zhen Zhen.

We began the hearing study on giant pandas about two years ago, with Bai Yun as our main subject. In the month before she gave birth to Yun Zi, Bai Yun decided that she wasn’t interested in our research anymore! Of course, we obliged her desire to be left alone and shifted our focus to Su Lin; she showed us her hearing was perhaps even more sensitive than that of her mom. Over the course of the last year or so, we have been able to collect a lot of data on Su Lin and, when our analyses are complete, we should be able to produce a comprehensive description of panda hearing—an unparalleled achievement.

Unfortunately, we haven’t had as much time to work with Zhen Zhen, but we have been able to pinpoint some important frequencies to test, and her data will make a very interesting comparison: Zhen Zhen’s young ears are in perfect shape, but are her listening skills as sharp as her older sister’s? Again, when the analyses are complete, we’ll have more answers.

Over the next week or so, we will work with Su Lin and Zhen Zhen as much as we can. The data are, of course, important, but the time the keepers and researchers get to spend with the bears is something to cherish.

After Su Lin and Zhen Zhen leave San Diego, we will reintegrate Bai Yun into the study and incorporate Gao Gao as well. Gao Gao has been working with keepers and getting ready to be a part of the study for some months now, and we are all looking forward to having a chance to work with him and study his ears as well.

Megan Owen is a conservation program specialist for the San Diego Zoo Institute for Conservation Research. Read her previous post, New Chapter for Su Lin, Zhen Zhen.


New Chapter for Su Lin, Zhen Zhen

Su Lin

When Bai Yun and Shi Shi arrived in San Diego from China in September 1996, the San Diego Zoo made it clear that it was committed to giant panda conservation. Bai Yun and Shi Shi captured the public’s attention, and the problems we encountered trying to get this mismatched couple to breed mirrored the predominate conservation problem that researchers were trying to tackle at facilities in China: How do you get giant pandas to breed in a captive setting? How do you get pandas to do what should come naturally?

Over the next 10 years, our interdisciplinary panda team worked tirelessly to study all aspects of reproduction, apply what we learned to the pandas at the San Diego Zoo, and develop a two-way exchange of knowledge with our partners at the Wolong Breeding Center in Sichuan, China. In 1996, only two females gave birth at Wolong. Although captive breeding was only one component of the conservation puzzle, it was clear that without a self-sustaining and genetically diverse captive population, the ultimate goal of reintroducing pandas to the wild would never come to fruition. But how quickly things have changed!

By the time I traveled to Wolong for the first time in the winter of 2000, the breeding center was enjoying a record-setting number of recent giant panda births (11 cubs!), and the San Diego Zoo’s Hua Mei, conceived through artificial insemination, was charming Zoo visitors and giving us a lot to study in the realm of panda cub development. The studies of panda behavior, reproductive physiology, genetics, and animal husbandry had all come into play to support the success at the San Diego Zoo, as well as at the Wolong Breeding Center.

Over the years, we (the Zoo’s Panda Team, visitors to the Zoo, and panda fans) have developed an incredible connection to and love of the pandas that have been born and raised in San Diego. Hua Mei’s departure from the Zoo marked our first experience with sending a San Diego-born panda to China. She was followed by Mei Sheng in 2007. Although we all knew it was for the best, it was a tough pill to swallow, and Hua Mei and Mei Sheng were sorely missed. Looking back now, however, with seven cubs representing Bai Yun and the completely unrepresented Shi Shi’s genetic make-up, we are very, very proud to have contributed to the broader needs of giant panda conservation.

Zhen Zhen

Soon, both Su Lin and Zhen Zhen will follow in older siblings Hua Mei and Mei Sheng’s footsteps. As I write this, I can tell you that I will miss these two bears! Su Lin is five years old, has already experienced her first fully developed estrus cycle, and is more than ready to join the conservation breeding program at the Wolong Nature Reserve Giant Panda Bi Feng Xia Base. Zhen Zhen is three years old now and will embark on her panda adolescence as part of the panda program at Bi Feng Xia as well.

Both Su Lin and Zhen Zhen have made incredibly valuable contributions to our research program and have contributed ground-breaking data on panda hearing sensitivity. These data will allow us to better estimate how noise from human activities may impact giant pandas in the wild. Collecting these data allowed keepers and researchers to work with both of these beautiful bears, up close and personal, on a daily basis. What a pleasure that has been!

As the drive to learn conservation-relevant knowledge of giant pandas shifts from captive propagation to reintroduction, we are excited that the pandas of San Diego will become a part of this larger conservation effort. Who knows? Maybe in the not-too-distant future, one of Gao Gao and Bai Yun’s descendants will one day be born in a large, old-growth tree den high in the mountains near Wolong. That image alone is enough to bring a smile to my face and makes me truly feel that the Giant Panda Team, and supporters of the San Diego Zoo’s pandas, have much to be proud of.

In preparation for their new adventure, Su Lin and Zhen Zhen will not be in public view beginning Monday, August 16, while they continue a training program that helps prepare them for the changes ahead. Their mother, Bai Yun, and her one-year-old cub, Yun Zi, will continue to be seen at the San Diego Zoo.

Megan Owen is a conservation program specialist for the San Diego Zoo Institute for Conservation Research Read her previous post, Birthday Celebration.