Smithsonian National Zoological Park l Friends of the National Zoo



2011 Panda Updates

December 19

David M. Rubenstein donated $4.5 million to the Smithsonian’s National Zoo to fund the giant panda program for the next five years. In appreciation, the giant panda complex—home to giant pandas Tian Tian (male) and Mei Xiang (female)—will be named the David M. Rubenstein Family Giant Panda Habitat. In addition, young conservation biologists in the U.S. and in China who are awarded National Zoo fellowships for their work to save this endangered species will be named “David M. Rubenstein Fellows.” The gift will be used to fund conservation efforts in China, reproductive science, professional training programs, giant panda care at the Zoo, upgrades to the Zoo habitats and public education.

“On behalf of the Zoo Advisory Board, we are most grateful to David for his generous gift, which keeps the beloved giant pandas at the National Zoo for Washington, D.C., and all Americans to enjoy,” said John Marriott, chair of the Smithsonian’s National Zoo Advisory Board. “More importantly, his generosity will enable us and our Chinese partners to continue our conservation work to give this critically endangered species the chance to survive in its native habitat.”

Rubenstein, co-founder and managing director of The Carlyle Group, has been a member of the Smithsonian’s Board of Regents since 2009. “We are honored to be part of a cherished program that brings joy to millions of people and draws together two great nations working to preserve these magnificent and gentle giant pandas,” said Rubenstein.

The gift allows the Zoo’s animal care and the Smithsonian Conservation Biology Institute’s scientific team to proceed with the five-year science plan established with their Chinese colleagues from the China Wildlife Conservation Association. The science plan has specific goals: to examine the creation and impact of corridors to link fragmented habitats that will benefit giant pandas and other wildlife species, including promoting genetic diversity; examine how to restore habitats, especially those where pandas appear to be making a comeback; provide advice on giant panda reintroduction; examine the potential impact of transmissible diseases on giant pandas and other wildlife species, including providing advice on implementing new programs associated with a Wildlife Disease Control Center being built in Sichuan Province; and continue research on giant panda reproduction and management, because, although there has been major success in Chinese breeding centers, some pandas still experience reproductive challenges.

This last goal extends to the Zoo’s pair of pandas who have only produced one cub, Tai Shan, via artificial insemination in 2005. SCBI scientists evaluated all panda breeding records and found that no female individual has successfully reproduced after five consecutive failures. Since Mei Xiang falls into that category, the SCBI team formed a 2012 breeding plan with some variations. “It’s important that we use modern biomedical tools to try and make sure that every genetically valuable individual panda reproduces,” said Pierre Comizzoli, SCBI reproductive physiologist.

The 2012 giant panda breeding plan was done in collaboration with Chinese colleagues. Most notably, the Zoo will receive frozen semen from the San Diego Zoo this year. The frozen semen will be from Shi Shi (now deceased). The frozen semen will be used only in the event that the pandas do not mate successfully and if Tian Tian’s semen is not of sufficient quality for an artificial insemination. Additional details of the breeding plan include: panda keepers continue to house the pandas separately as they would live in the wild although they are rotated throughout all the yards, panda keepers continue the animal training and exercise regimens to improve their stamina, alterations are being made to the facility to create smaller and more manageable breeding areas, all unnatural night light in the building has been eliminated and the indoor panda exhibit is closed to the public at 4:30 p.m.

Tian Tian, the male panda, has already exhibited preliminary rutting behaviors (“powerwalking”/patrolling, urine hopping, scent marking and some vocalizations). Keepers expect these behaviors to increase over time. Mei Xiang has yet to exhibit any estrous behaviors. Last year at this time, she was beginning to show early behaviors such as scent marking, restlessness and vocalizations.

Zoo receives $4.5 million for giant panda conservation
From left to right: David Wildt, head of SCBI's Center for Species Survival; Wayne Clough, secretary of the Smithsonian Institution; Ambassador Zhang, People’s Republic of China; David Rubenstein, donor; and Dennis Kelly, director of the Smithsonian's National Zoo.

December 16

As the temperatures drop and the holidays approach, many people’s thoughts turn to shopping lists and gatherings with friends and family. Winter at the Panda House, though, signals the time for keepers to start looking ahead to the next breeding season, both for red pandas and giant pandas. The red panda family has now been reunited, and they are currently living in their outdoor habitat on Asia Trail. When the cubs are weaned by their mother, Shama, we will separate the cubs from the parents and will manage two groups of red pandas again. This separation will allow Shama and Tate their privacy for their next breeding season, in mid to late winter. The cubs, Damini and Pili, will then be able to continue living here at the National Zoo until they are ready to be paired for breeding themselves.

Tian Tian, our male giant panda, is beginning to show the early signs of rut behavior. He is spending more and more time patrolling his yards, and scent-marking everything in his path, with the scent glands located at the base of his tail. In the wild, male giant pandas would be doing the same thing—searching over their territory in hopes of finding a fertile female. We are giving Tian Tian multiple yards, as well as switching yards whenever possible to facilitate these natural behaviors. Mei Xiang has not been showing signs of coming into estrus any time soon. We do know that with her early cycling in both 2010 and 2011, Mei can be very unpredictable and continues to “re-write” the chapter on giant panda reproduction! Even so, we are hopeful that Mei Xiang will wait until spring to come into estrus, which is more species-typical. We are also hoping that if she falls back into a more “textbook” pattern for breeding, that she will be successful in having a cub in 2012.

Mei Xiang

December 1

Mei Xiang and Tian Tian have a new hobby—painting! As part of our behavioral enrichment program, keepers have started painting with the pandas. Many animals throughout the zoo paint already, and the pandas seem to enjoy it as much as the other animals. Only non-toxic paints are used (the same ones that preschoolers use for finger-painting) so they are safe for the animals. Tian Tian painted extensively on Sunday, and after he was done, even used the paint to “scent anoint.” Pandas will often rub a particularly appealing scent around their ears. Visitors have probably seen Mei Xiang scent anointing with old branches and bark outside. The paints seem to be just as exciting for the pandas when it comes to scent anointing!

To keep things interesting for the pandas, painting will just be another type of enrichment that will be used on a rotating basis. If they painted every day, it wouldn’t be as novel or interesting. So look closely at the pandas in the future—you may just see a small smudge of green or blue paint, amongst the black and white fur! When you see that, you’ll know that they’ve recently been practicing their art.

Male giant panda Tian Tian painting at the Smithsonian's National Zoo
Tian Tian exercising his artistic abilities.

November 1

In China as well as in giant panda holding facilities outside of China, including the National Zoo, young pandas are often socially housed. It is a frequent sight in the breeding centers in China to see panda “kindergarten,” where many cubs born in the same season are housed together after they’ve been weaned. Older pandas are less social and less interested in each other, and are not typically housed together, due to increased risk of aggression, and also as part of breeding management. When Mei Xiang and Tian Tian were younger, they spent most of their time together and played together very well. As they’ve become older, however, they have become less interested in this socialization.

Mei and Tian will be reintroduced during the next breeding season based on the recommendations made by the Species Survival Plan for giant pandas, but only during the short period of Mei’s estrus. Adult giant pandas in captivity are housed separately most of the time. This mimics their patterns of behavior in the wild. Giant pandas are mostly solitary animals, although they communicate with each other through olfactory and auditory cues. Mei and Tian continue to be housed next to each other, and can still communicate with each other through those means. We are hoping that the old saying “Absence makes the heart grow fonder” will hold true and that we’ll have a successful breeding season in 2012.

October 3

Although the weather in D.C. has been mostly gloomy for the last couple of weeks, Mei Xiang and Tian Tian don’t seem to be bothered. Giant pandas are adapted for life in a cool, rainy climate. They have thick coats, with oily fur to help them stay warm and dry. In the Sichuan Province of China, where most wild giant pandas are found, the average rainfall is 35 to 47 inches per year. By comparison, Washington averages about 39 inches. Both pandas actually seem to be enjoying the cooler, albeit rainy, weather and are spending much of their time napping in their yards.

As cooler weather approaches, we see the pandas’ bamboo consumption increase. Currently, Mei and Tian are eating about 55 to 66 pounds of bamboo each day. In the winter, when their appetites peak, they can each eat about 110 pounds of bamboo a day! In the winter months, they also shift from eating mostly leaves to eating primarily the culm, or woody stalk of the bamboo.

September 13

Mei Xiang and Tian Tian have new neighbors! Shama and Tate, the red panda pair from Asia Trail, along with their two yet-unnamed female cubs, have taken up temporary residence in enclosure #4 of the giant panda house. The red pandas were moved as a precaution several weeks ago as Hurricane Irene approached. Since they are doing so well here, we are going to have them stay a bit longer as modifications are made to their permanent exhibit to make it more cub-friendly. In the meantime, visitors can take a peek at the adults, between 10 a.m. and 6 p.m. If you’re really lucky, you may even catch a glimpse of the cubs, who are just starting to venture out of the nest box. The red pandas may also be viewed on Panda Cam 2 for a while.

Mei Xiang and Tian Tian don’t seem to be fazed by their new neighbors in the least. In the wild, their ranges would overlap slightly. In general, the red pandas would be more arboreal, while the adult giant pandas would be more terrestrial.

September 8

On Saturday, September 3, giant pandas Mei Xiang and Tian Tian had a belated birthday celebration. Mei Xiang was still “denned up” at the end of her pseudopregnancy and missed her 13th birthday, July 22. Tian Tian turned 14 on August 27, just as Hurricane Irene passed through.

panda with a birthday treatSo, Zoo staff presented the pandas with belated birthday enrichment items—huge, elaborately decorated ice cakes filled with fruit, juice and vegetables, created by the our department of nutrition, and kiddie pools filled with ice cubes and fruit bits for foraging. Not long after all the excitement, both pandas could be seen napping by the remnants of their ice cakes.

July 25

We are all truly disappointed to not have a new panda cub this year. We were sure that all of our hard work and the help from our Chinese colleagues, as well as all the positive energy from panda fans everywhere somehow would have all come together for a positive outcome after many years of disappointment. Even in our disappointment, we have to step back and realize how much we learn each year, whether or not we have a giant panda cub. This knowledge helps us better care for these magnificent animals.

We are again starting to see glimpses of the Mei Xiang that we typically see during non-breeding seasons. Although the extreme heat is slowing down her return to “normal,” she is beginning to engage in her usual routine again. For example, Saturday morning, she ventured into the scale area to be weighed and to participate in a brief training session. She weighed 236 pounds, which is 19 pounds lighter than her last weight which was taken at the end of May, but this is a normal weight loss considering the amount of time she’s been denned up and eating less. She is regaining her interest in food, and is consuming all of her produce and leaf eater biscuits daily, along with increasing amounts of bamboo.

Mei Xiang is the one who will determine when she returns to her outdoor yards. We expect that some morning in the very near future, she will be awake and waiting for us by the door when we arrive in the morning, just like before the pseudopregnancy. At that time, we will let her set the pace for her return to her normal daily routine. Once she begins sleeping outside of her den on a regular basis, we will begin deconstructing the enormous nest in her den, so that we can again thoroughly clean her enclosure. Then life will go back to normal at the Panda House, and we will eagerly await the next breeding season.

July 21

Two red panda cubs were born at the Zoo in Washington, D.C., and two additional cubs were born at the Zoo’s facility in Front Royal, Va., bringing the total to four in 2011. Unfortunately, Mei Xiang is not pregnant but was experiencing a pseudo, or false, pregnancy during the past several months.

Shama, the female red panda at the Zoo’s Asia Trail, gave birth to two cubs in her den June 17. Keepers suspected that she was caring for offspring when she did not respond to their call that morning. A slight squeal was the first indication of a cub. Zoo staff left the mother alone to bond with and care for the cubs in their den. On the seventh day keepers conducted a quick cub check and, with a one-minute window of opportunity, were able to confirm two cubs in the nest box. Likewise, red panda Lao Mei at the Zoo’s Smithsonian Conservation Biology Institute in Front Royal gave birth to two cubs June 5. Keepers have confirmed both cubs are female and have opened their eyes.

Staff are taking precautions to not interfere with the cubs during this critical time. As the opportunity presents itself, they enter the den areas to weigh the cubs and assess their health. Keepers wear a second set of cloth gloves over their standard rubber gloves, which have been rubbed with nesting material and scented with the mother’s feces to cover human scents. All four newborns are steadily gaining weight and appear healthy.

The red panda exhibit is currently closed to visitors for the safety and well being of the mother and cubs. As the cubs grow stronger, the keepers and Friends of the National Zoo volunteers will watch for Shama to allow her cubs to venture out of the den in early fall. At that point, staff will evaluate when the exhibit can be reopened for public viewing. The red pandas in Front Royal have a brand new facility that includes nine outdoor enclosures equipped with numerous insulated dens. Red pandas are born annually and more than 100 surviving cubs have been born at both the Front Royal and Washington facilities since 1962.

National Zoo scientists, veterinarians, keepers, and volunteers from Friends of the National Zoo were keeping a close eye on giant panda Mei Xiang, monitoring her hormone levels and behavior, as well as conducting daily ultrasound exams in an attempt to determine if she was pregnant. (Note: Mei stopped participating in the ultrasound exams after July 3 and remained exclusively in her den.) In late June, giant panda Mei Xiang’s level of urinary progesterone (a hormone associated with pregnancy) began to gradually decline. Upon reaching normal baseline levels, this decline would end in either the birth of a cub or the end of a pseudopregnancy. Based on changes in her behavior, hormone levels and a lack of fetus observed during the ultrasound exams, Zoo researchers have determined that Mei Xiang experienced a pseudopregnancy.

Giant pandas ovulate just once a year. Females undergo a pseudopregnancy when they ovulate but fail to conceive. During a pseudopregnancy, hormonal changes and behaviors are identical to those of a true pregnancy, making it very difficult to determine if a giant panda is actually pregnant or not. This is the sixth time Mei Xiang has had a pseudopregnancy. She gave birth once in 2005 to a male cub, Tai Shan.

Zoo staff expects Mei Xiang to return to normal, hormonally and behaviorally, in the coming days, which includes an increase in appetite and activity level. Although Tian Tian has been on exhibit all summer, Zoo visitors will soon get a chance to view Mei Xiang. The David M. Rubenstein Family Giant Panda Habitat opens daily at 10 a.m. Mei Xiang’s area of the house had been closed to provide her with a quiet environment in the event that she did give birth.

July 13

Mei Xiang continues to throw us curve balls this year. Last week she exhibited behaviors consistent with coming out of a pseudopregnancy, including increased appetite and awareness, and spending time outside of her den. However, last Thursday morning, she “denned up” again, spending almost all of her time in her nest area, eating very little, and sleeping even more than usual. She has also gone back to cradling and grooming both her Kong toy and Boomer ball. Prolonged bouts of body licking have been observed, which is another strong indicator for possible imminent birth. In the midst of all of these encouraging signs, she didn't produce a fresh urine sample until last night. Right now we are all anxiously awaiting the results of that sample, which hopefully will give us a much clearer picture of where things stand.

Due to the extreme heat, Tian Tian is visible outdoors only in the early morning hours. At about 10 a.m. he is given access to his air-conditioned indoor enclosure. We apologize for any inconvenience this may cause, but our priority is to provide the best care possible for Tian Tian during this heat wave.

July 8

Mei Xiang continues to keep us guessing. Last week we saw her hormones decreasing and her activity increasing. With no evidence of a fetus on the daily ultrasounds, we were beginning to await the end of a pseudopregnancy. However, during the past two days she has remained in her den, eating very little, cradling her toys, and body licking. She has not given us a urine sample to check for hormones or been willing to participate in ultrasound, so we can’t confirm what this behavior means. This is a reminder that it is important for us to have pandas at the Zoo as every new behavior is a valuable data point that helps us understand more about the reproductive habits of these amazing animals.

July 1

Mei Xiang has been spending a lot of time away from her nest, and her appetite has increased markedly. In the past couple of days she showed some signs of pregnancy, such as anogenital licking, but our veterinarian colleagues have not detected a fetus during any ultrasound procedures. The fact that she has been eagerly participating in the ultrasound training is a behavioral indicator that is typically linked to a hormonal return to baseline. We expect to have more information next week.

During the holiday weekend, we will continue our close observations and take our cues from Mei Xiang. When she is awake and alert in the morning and looks like she wants to venture outside, we will open the door and give her the opportunity to enjoy her yard. As she shows more interest in food, we will gradually increase the quantity given to her.

June 29

Mei Xiang has been seen doing a lot of paw-licking during the overnight and early morning behavior watches. This behavior is encouraging, as it is a behavior that pregnant pandas often exhibit, but is also seen during false pregnancies. A behavior that is more indicative of a true pregnancy is anogenital (or "AG") licking. Back in 2005, Mei Xiang exhibited prolonged bouts of this behavior for several days prior to giving birth to Tai Shan. Beginning in the wee hours of the morning on June 25, behavior watchers noted a couple of short bouts of AG licking. While this is no way conclusive as to whether or not Mei Xiang is really pregnant, it is certainly a positive sign.

The vets are still conducting ultrasounds on Mei Xiang almost every day. For the most part, she is still very cooperative, although she is very clear when she is done participating. Nothing definitive has been seen yet, but we’re still all waiting and hoping.

June 22

Mei Xiang is spending even more time in her den these days. She continues to eat very little, and spends almost all her time conserving her energy, which is consistent with both pregnancy and pseudopregnancy. She has been intermittently participating in ultrasound sessions, picking and choosing which times are agreeable to her, but there have been no significant findings thus far.

The 24-hour behavior watch began Monday morning. Our dedicated team of Friends of the National Zoo behavior watch volunteers is an integral part of the panda program, manning the cameras round the clock. They are given special training with specific instructions on the behaviors that indicate imminent birth. Panda staff are on call round the clock as well, ready to race to the Zoo once those behaviors have been observed. We know that a birth can occur any time, day or night. Mei Xiang’s first cub, Tai Shan, was born at 3:41 a.m. Panda keepers eagerly await that kind of wake-up call!

June 15

Mei Xiang continues to spend most of her time indoors, resting on the mountain structure and adding to her nest. She is still participating in ultrasounds, which are now occurring three times a week, but she's becoming even more sensitive to noises around her. Over the weekend, when keepers attempted to re-shave her belly, she was easily distracted by the sound of the clippers as well as the birds calling over the training cage.

Mei Xiang has also become pickier when it comes to the kinds of produce she's eating. She has been leaving her cooked sweet potatoes (usually a favorite treat) for the past several days. Also, during Monday’s ultrasound, she refused to take any apple pieces, and would only train for pear rewards. When the ultrasound was completed, she cradled her half-pear “jackpot” for several minutes before consuming most, but not all, of it. Her behavior continues to keep us guessing.

June 8

Tian TianThis year, spring seemed to last only a few days, which didn't give the pandas a chance to ease into the warmer temperatures like they usually do. Although the temperature ranges are pretty much identical in Washington, D.C., and the Sichuan province of China, our pandas do not seem to be fond of the sweltering summer weather. We keep Mei Xiang and Tian Tian comfortable by keeping the pools in their yards full of water for wading and by offering frozen treats. The pandas’ yards have cooling features such as water misters and foggers, lots of shady spots for resting, and cooled rockwork. On most summer days, you will find Tian Tian napping in his favorite cave, with his head resting near the air vent. When the weather really heats up, the pandas prefer resting indoors in their air-conditioned habitats. We notice a decrease in both activity and appetite when the temperatures soar into the 90s.

Mei Xiang has been spending most of her time indoors lately, most days only going out for a quick bamboo breakfast. Within minutes, she is waiting at the gate for us to finish cleaning her enclosure. Once inside, she usually climbs onto the rockwork for a long nap. This behavior is consistent with previous years, and is typical for pregnancy or psuedopregnancy. Now that her appetite has dropped off almost completely, we know we’re nearing the end of the pregnancy or pseudopregnancy. Mei Xiang has also been consistently adding to her nest in the den—it doubled in size over the weekend!

June 1

Panda mothers give birth to twins about 60 percent of the time. In most cases in the wild, the female would simply not be able to care for both, and would focus all of her time and energy on the stronger cub to ensure its survival. Occasionally in captivity, a female is able to raise twins with only a little help from human caregivers. Our Chinese colleagues have developed a method of twin swapping that has greatly increased survival rates of panda twins. Each day, one twin is removed to receive supplemental hand-feeding in the nursery from specially trained staff. The other cub is left to receive care and nourishment from the mother. The next day, the cubs are swapped. Staff members from the National Zoo have traveled to China to observe this process and to receive training in nursery operations for neonatal panda cubs. Based on these observations, our staff have developed a plan for twin swapping and nursery care.

Mei Xiang has been busy constructing her nest of bamboo and mulberry branches, adding bamboo shreds almost every night. She has moved a drain cover into her nest, as she has in previous years. While Mei continues work on her nest, the panda keepers are doing a bit of nesting as well. Keepers annually prepare and re-stock the nursery, just in case there are twins, or a single cub that needs a little extra attention in order to thrive. The hope, of course, is that Mei Xiang will exhibit the same phenomenal mothering skills she showed in 2005, with the birth of her first cub, Tai Shan. We still have to be ready for any outcome, or to offer any extra help that Mei may need.

May 25

Mei XiangIf you’ve visited the panda house or tuned into the panda cams recently, you may have noticed something about Mei Xiang that you hadn’t before—her cute freckled belly! This is because keepers have been able to shave her closer than in previous years, allowing the Zoo's veterinarians to get a clearer ultrasound picture. Mei Xiang eagerly participates in ultrasound training twice a week, seemingly motivated by the pear and apple bits she receives as reinforcement, and the ultrasound gel that she rubs off of her belly and onto her ears after each session is completed.

As the pregnancy watch continues at the panda house, the keepers are also focusing on a different type of training with Mei Xiang—den training. Den training begins with getting Mei Xiang comfortable with the keepers being next to her in a specially designed area of the den, where safety bars separate the staff from Mei Xiang but still allow close proximity. From this protected area, a prized item, such as a pear, is removed through the bars using modified grabbers, which have special cushioning on the grabbing end (to be extra gentle). Mei Xiang is praised for her cooperation and for not trying to prevent the removal of the object, and is rewarded with food. The understanding is that the item is returned for her to enjoy at the end of the session. In the event of a twin birth, this is how keepers would retrieve a cub for supplemental feedings in the nursery. A high level of trust needs to exist on both sides for this to be successful. Mei Xiang does extremely well with den training, as she does in all other aspects of her training.

May 17

We are waiting and hoping to hear the pitter-patter of little panda paws in the coming weeks. It is still too early to determine whether or not Mei Xiang is pregnant, but we hopefully make preparations in case she is.

Mei Xiang has begun her secondary progesterone rise, an indicator that the pregnancy or pseudo pregnancy will end in the next several weeks. Staff and behavior watch volunteers are carefully looking for every little behavior sign to coincide with the hormonal data—nest building, decreased appetite and energy, cradling objects—which will give us a more accurate timeline of when to expect the birth or the end of pseudo pregnancy. For now, we are in a wait-and-see mode. The veterinarians are conducting ultrasounds twice a week, hoping to catch a glimpse of a cub. After each ultrasound, Mei thoroughly enjoys rubbing the ultrasound gel all over her ears before eating her pear reward.

The million-dollar question around the panda house continues to be “Is she or isn’t she?” Panda house staff and volunteers are not being evasive with our standard “I don’t know” answer—it truly is too early to know for sure. In the meantime, we can all cross our fingers in hopes of a new little bundle of panda joy in early summer.

February 1

Mei Xiang and Tian TianOur giant panda mating season began early for the third consecutive year with Mei Xiang and Tian Tian attempting to mate on January 29. Mei continues her January ovulation pattern that started in 2009; historically her estrus occurred in March or April.

In accordance with the new Giant Panda Cooperative Research and Breeding Agreement, reproductive experts from the China Conservation and Research Center for the Giant Panda in Wolong and experts from the Smithsonian Conservation Biology Institute will collaborate on the breeding plan for Mei and Tian for 2011 and 2012. Tang Chunxiang, the Chinese Center’s chief veterinarian, flew here last week to work with the Zoo’s panda team.

On January 29, Tang, alongside Zoo scientists and veterinarians, performed the first of two nonsurgical artificial inseminations on Mei Xiang after it was determined that competent natural breeding between the pair had not occurred. Due in part to the bears’ rigorous attempts at natural mating, efforts to retrieve semen from Tian Tian were not successful. The team decided to thaw high-quality semen of Tian Tian collected and frozen in 2005. Mei Xiang was then anesthetized for the procedure. A second artificial insemination was performed on January 30.

“Both procedures went extremely well and the staff at the Zoo were happy to collaborate with Dr. Tang,” said Pierre Comizzoli, a research physiologist at the Zoo. “Comparing our process and Dr. Tang’s in China, we found our insemination techniques were very similar. Both countries really do have common practices in giant panda reproduction. We are all hopeful for a cub this spring.”

Giant pandas have one very brief breeding season each year, with only a day or two of actual mating. The early start of these past three seasons is unusual, but the expertise of the Zoo’s staff enabled them to immediately identify signs of this early reproductive activity and prepare natural mating as well as a possible artificial insemination.

As early as two weeks ago, the Zoo’s animal care team noticed Mei Xiang exhibiting signs of estrus, including distinctive vocalizations that are associated with mating season. Staff immediately began monitoring the hormone levels in her urine, which allowed them to predict when she was in peak estrus and most fertile. Timing is crucial—female giant pandas only have about one day a year in which conception can occur.

There is no conclusive study that indicates what induces the breeding season in giant pandas. Although scientists know that they mostly breed in late winter to early spring, it is not known if the onset of reproductive activity is triggered by increasing day length, temperature or some other environmental factor.

The Zoo took measures to provide optimum conditions for both pandas prior to mating. Automatic lighting and excessive noise were kept at a minimum at the panda house afterhours, which included closing the exhibit to visitors during the Zoo’s evening holiday event, ZooLights last month.

In addition, keepers worked for several months on the physical stamina of the bears in preparation for mating season. Tian Tian underwent behavioral training to stand tall on his hind legs by receiving food treats to build stronger leg muscles; Mei Xiang was trained to lie across a large log in her enclosure to improve her breeding positioning.

“We wanted them to be well-rested and in the best possible shape physically to breed naturally,” said curator Brandie Smith. “And if there was anything we could do to enhance that success, then we did our best to apply it.”

Tang is an expert in breeding pandas in China. He worked with Mei and Tian to encourage natural breeding over several days; however, the pair never successfully mated. Therefore, Zoo staff separated the bears before performing the artificial insemination. They will remain separated for the next few months, until Mei either delivers a cub or Zoo scientists determine that she is not pregnant. Keeping the pandas separated will reduce the risk of increased stress-hormone levels in Mei Xiang, which could jeopardize a developing embryo.

Panda gestation typically lasts from 90 to 185 days. Veterinarians and scientists will monitor Mei’s hormone levels and perform ultrasounds to determine if she is pregnant. At present there is no way of knowing for sure if she conceived; hormone levels are the same regardless of whether she is pregnant or pseudo pregnant.

Mei and Tian have produced one cub, Tai Shan, who was born July 9, 2005, as a result of artificial insemination. Tai Shan now resides at the China Conservation and Research Center for the Giant Panda in Wolong, China.

January 20

As President Barack Obama met with President Hu Jintao of the People’s Republic of China this week, another notable U.S./China meeting took place this morning at the National Zoo.

Dennis Kelly, the Zoo's dirctor, and Zang Chunlin, secretary general of the China Wildlife Conservation Association, signed a new Giant Panda Cooperative Research and Breeding Agreement, extending the Zoo’s giant panda program for five more years, further cementing the two countries’ commitment to the conservation of the species. Celebrate the news—adopt a giant panda!

The new agreement, effective immediately through December 5, 2015, stipulates that the Zoo will conduct research in the areas of breeding and cub behavior. The first two years of the agreement include a cooperative study involving reproductive experts from the China Conservation and Research Center for the Giant Panda in Wolong, China, and the Smithsonian Conservation Biology Institute; they will oversee the breeding of Mei Xiang and Tian Tian.

If, after two years, either panda is found unsuitable for breeding, the two institutions will discuss the possibility of exchanging them with breeding pandas from China. The current pair has not produced a cub since 2005, when Tai Shan was born. Tai Shan was sent to China in February 2010 per the terms of the former agreement. If another cub is born at the Zoo, it will stay until the age of four. Previously, cubs were sent to China before age two. Both parents and any offspring remain under the ownership of China.

“We are happy to announce that for now, we will keep our beloved Mei Xiang and Tian Tian at the Smithsonian’s National Zoo,” said Kelly. “With only about 1,600 now found in the wild, giant pandas are among the most endangered animals on Earth, so it is a great privilege and responsibility to have two animals in our care.”

Ken Salazar, secretary of the Department of Interior commended the work of a delegation from the department’s U.S. Fish and Wildlife Service that met with Chinese officials in Beijing late last year to strengthen ties on panda conservation and improve coordination in the overall effort to save the species and its rapidly declining habitat.

Those successful discussions led to consensus on a new framework for working with China on its priorities for giant panda conservation. Under the new framework, the government of China will fund specific projects to support wild panda conservation based on a mutually agreed list of activities. 

“The loan of giant pandas to the National Zoo has long symbolized the close partnership the United States has with China as we work together to conserve and recover one of the world’s most endangered species in the wild,” Salazar said. “I am proud that this agreement not only ensures that visitors to the National Zoo will continue to be able to visit and learn about these beautiful animals, but also provides a strong platform for improving the conservation of wild pandas and their habitat in China.”

Mei Xiang and Tian Tian have lived here since December 6, 2000. They were both born at the China Conservation and Research Center for the Giant Panda in Wolong; their parents were born in the wild.

January 13

There has been no significant progression of estrus behavior from Mei Xiang this week. On January 8, Mei bleated once in the morning and then had a restless day with frequent scent marking. None of this behavior was repeated during the week. Mei Xiang’s estrogen levels remain at baseline. Tian Tian has had another consistent week of rut behaviors.

Yesterday, a light snow coated everything in crystalline white to interrupt the pace of life at the panda house. While keepers struggled to move bamboo and keep warm, the pandas did their best to wrap themselves around the meager snowfall. They rolled and tumbled on the hills, the snow providing an exhilarating coating of renewal to their usual habitat haunts. We were all privileged guests, watching their inner cub emerge again. While watching their fun in the snow, that fleeting moment of civility, peace, and beauty knows no words.

January 7

It is a happy and hopeful new year at the panda house. For the past two years Mei Xiang has come into estrus (her ovulatory period) in January. The average female panda experiences estrus between March and May, and Mei Xiang was on this more typical schedule up until 2009, when she surprised us with this very early estrus.

When females are in estrus, it's as though someone pushed a fast-forward button. They become very restless and pace, pausing to scent mark (rubbing their tails on surfaces) every few steps to announce their impending brief two-day window of fertility. One particular vocalization called a bleat is also heard during this time. A bleat is a contact call between pandas, heard when they interact with each other (or their keepers). Mei Xiang usually only emits this low, soft, sheepish sound when she is ready to mate. In 2010 her first recorded bleat was followed by peak estrus, just 11 days later. This year her first bleat was heard 20 days ago! So far Mei has yet to show any additional signs of estrus. We expectantly watch her behavior and monitor her hormones for a rise in her estrogen levels. Each year is a bit different, and so we are left guessing about her timing.

Tian Tian is ready, and no guess work is required. Unlike Mei, Tian bleats all year round to the keepers on a daily basis to indicate his need for food or attention. As a male panda, his male hormone testosterone rises in early winter in preparation for the breeding season. Tian becomes extremely restless and patrols his yard expectantly. If only it could rain female pandas! When he is rotated into Mei Xiang’s yards he inspects where she has been and leaves his scent mark behind. During this time he adds an odd hopping-forward motion when urinating to add spread and extra emphasis.

In the wild, male pandas have to compete with other males in their home ranges for breeding access to females. Studies have shown that placement of scent marks communicates the status, size, and maturity of males and females in the area. Tian Tian has recently taken to scent marking in trees, proving to all that he is truly a giant among pandas.

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