San Diego Zoo’s Panda Team


The Scoop on Panda Poop

Yun Zi munches his bamboo like a pro!

Yun Zi munches his bamboo like a pro!

I spoke with panda narrator Alyssa Medeiros to get the latest on our bamboo bears. Alyssa has been helping the San Diego Zoo’s Panda Team as a panda keeper these days and promises to write a blog about that experience when she can. In the meantime, she shared some fun stuff about our two youngest bears.

Yun Zi is a typical “teenaged mess maker,” according to Alyssa. This four year old panda continues to rip and shred anything he can get his paws on. Yet his most challenging mess for keepers to clean is his location of choice for bathroom duties. Yun Zi has decided that the top of the artificial den is the perfect spot. Why does this make extra work for his caretakers? The poop goes into the den’s nooks and crannies, making it more difficult to clean. Apparently, he cares not!

Xiao Liwu, nicknamed Mr. Wu, is now leaving “treasures” behind. Previously, his mother, Bai Yun, would clean up any waste her cub left behind, presumably so predators would not be alerted to his presence. But now that he is larger and starting to ingest, rather than just mouth, bamboo leaves, he is producing “little gifts.” Apparently, Bai Yun is willing to let keepers dispose of them these days. Talk about room service! Alyssa says that Mr. Wu is also chewing on sticks and attempting to peel the larger bamboo culms—an advanced skill for a panda boy of just 14 months. He has not attempted to chew those culms yet but often mouths some of Bai Yun’s shredded leftovers.

Xiao Liwu’s training sessions continue, and Alyssa is quite proud of his progress. He has learned to touch his nose to a pool buoy on a stick (it looks like a very large Q-tip!) and to a dot on the wall for a honey water reward. And he is getting better at shifting off the exhibit and into his bedroom when asked.

Thank you for the update, Alyssa!

Debbie Andreen is an associate editor for San Diego Zoo Global. Read her previous post, Our Panda Family.


Pandas: Unraveling a Mystery

A wild panda rests in a tree in China's Foping Nature Reserve.

A male panda sits, hour upon hour, lazily grabbing bamboo stems, pulling them to his mouth, where powerful jaws and crushing teeth make short work of it. A few hours later, it comes out the other end, changed little by the passage through his intestines. After a few days of this routine, intermittently sleeping and eating in a circumscribed area, the panda rouses and begins heading up the slope. He pushes through the dense bamboo, slow and shuffling but somehow graceful.

Upon reaching the ridge, he enters a different world—the dense bamboo gives way to open understory beneath a towering canopy of ancient spruce and fir trees. It’s a pleasant enough place for a picnic, but for pandas, the picnicking is better below in the valley. This panda has come here not to eat but to communicate: this ridge is like a community bulletin board, and scent messages are posted on these ancient trees.

Every move a panda makes is calculated to conserve energy. Even his placement of scent marks is efficient. He walks past a smooth-barked tree in favor of one with rough bark, lifts his tail, and rubs his gland in a circular motion. His scent is spread across little crevices that increase the surface area, maximizing the “odor field” of his scent. He approaches another tree and sprays urine over the trunk while doing a handstand.

He chooses a large tree, lest he miss his target and let the golden message fall to the ground. He needs his urine mark to be up high; it will waft farther through the air where it is more likely to capture the attention of a passing panda. The height of his mark also conveys his status; other pandas will read “dominant male,” at least in this neck of the woods. For a urine mark, he chooses a tree with ultra-rough textured bark that captures the urine, keeps it from trickling down the trunk, and perhaps keeps it from washing off easily in the frequent rainfall characteristic of these Chinese mountains.

Other pandas will be able to read his urine mark for about two weeks, but the mark from his gland will last four months! This way he does not to have to climb back up to the ridge again for a few weeks. He ambles further down the ridge path, stopping to sniff the marks left by pandas that have come before him. This one, his nose tells him, comes from a young male that came here and left his scent several weeks ago; it represents no threat.

The next one, however, came from another large dominant male. He has tangled with him before, he remembers, and two years ago this male bested him in a long, drawn-out contest for access to a fertile female. The next mark encountered really gets his attention: it’s from that same female, and she is again nearing her fertile period. After leaving the scent ridge, he will expand his range in search of signs of this female. She will be marking frequently now, and several males will catch her scent and track her down. There’s bound to be trouble.

Such is the life of a giant panda. I can be relatively certain about my scenario only because of years of study, working with many partners and colleagues at breeding centers in China and wild pandas at the Foping Nature Reserve. Our collective effort allows me to paint this picture and begin to unravel the mystery of this rare and difficult-to-study species.

We now know, for example, that pandas require very different habitats for communicating with one another than what they need for foraging. We must work to protect all the panda’s habitat, including the palette upon which they paint their scent messages.

Ron Swaisgood is the director of Applied Animal Ecology, San Diego Zoo Institute for Conservation Research and co-head of the San Diego Zoo’s Panda Team. Read his previous post, Cocha Cashu: Exploring Uncharted Territory.

Author’s note: The story described here is derived from years of collaborative research with many partners, most prominently Professor Wei Fuwen’s Key Laboratory for Ecology and Conservation Biology at the Institute of Zoology at the Chinese Academy of Science and the China Conservation and Research Center for the Giant Panda.

Photos courtesy of the Institute of Zoology, Chinese Academy of Science.

Visit San Diego Zoo Global’s Wildlife Conservancy website for photos, videos, and great stories of our work to help wildlife near and far.


Considering the Sisters

Zhen Zhen

Zhen Zhen

Many of you have asked if we are planning to put our young panda girls Su Lin and Zhen Zhen together for a full-contact playdate. I wanted to offer some insight into the San Diego Zoo’s Panda Team’s thinking as to why this will not happen for these girls.

You may be familiar with our constant references to the fact that the panda is a solitary animal. You may then be surprised to hear that this was not a factor in determining not to put these two bears together. In fact, we readily acknowledge that when pandas are young, they are more apt to be social than when they are adults.

There is some evidence that wild sub-adult males may shadow adult males as they travel throughout their home range. The young animals may not be much of a threat to an older, established male, and may therefore be tolerated. We have seen in San Diego how social our youngsters are, and in need of some kind of contact, shortly after weaning. Of course, mother bears with their dependent offspring are not living alone. Certainly, at various points in their lives pandas are not solitary.

Being solitary is a lifestyle employed by wild adult pandas, most likely as a strategy for coping with their food supply. We have all seen pictures or video of brown bears congregating at salmon hot spots along rivers. The bears are willing to ignore each other in those feeding zones because the food is abundant and nutrient- and fat-dense. Why don’t pandas do the same? Bamboo stands do not pack much of a caloric punch, requiring pandas to consume large quantities of the plant to achieve the full meal they need to fuel their bodies. The best way to get that belly full is to find a patch of bamboo, sit for a while, and eat heartily. However, if a gaggle of pandas sat together, the food in the area would be depleted that much more rapidly, requiring the bears to get up and hunt around for more to eat, a process which burns calories. From the energy equation point of view, it makes more sense not to have to share.

No, there are other reasons we have concerns about putting our two girls together. For one: Su Lin is now four years old and has had her first estrus. She is no longer a little sub-adult bear. In Wolong, several females have given birth at age five, and it is likely that Su Lin’s spring hormonal changes will be very dramatic, reflecting her new status as a full-fledged adult. These hormonal swings, however, open the door to aggressive behavior on her part. Though we don’t expect an estrus from her until early next year, we can’t guarantee that she will not experience some aggressiveness at other times as her body continues to mature and grow. Though Su Lin is generally considered a sweet-tempered animal, it would be good to remember that Mei Sheng was always thought to be sweet as well. Yet, at the age of four, he climbed over a wall in his Chinese home and picked a fight with another panda. Sweet-tempered or not, both of these bears are just that: bears.

Given her larger size as compared to Zhen Zhen, an aggressive encounter instigated by Su Lin could turn out badly for our youngest female. Bears in China are put together as members of the same age class and so are matched for size. Among adult bears, temperament is weighed heavily in making these pairings, and the older bears are placed together in large pens with many options for solitude should one or both bears require it. In fact, our panda narrators have observed some aggressive interactions through the howdy gate that have caused Zhen Zhen to keep her distance from the gate recently, seeking solace away from her sister. For this reason, we will desist with howdy gate interactions between these bears at this time. It appears the enriching value of these protected-contact episodes may have run its course, for now.

Finally, even if signs for direct contact were favorable, the resulting play sessions would be short lived. Su Lin will be journeying to the land of her mother’s birth in the next year, as China has requested. Even more pressing, Bai Yun and her young cub will be moving down to the howdy gate area in December, with preparations for this beginning several weeks prior. At that time, one or both of the girls will need to rotate back to the classroom area, enclosures not well suited for direct contact. In the end, the time allotted for direct contact would be a few weeks at most.

Our team has the very best interests of our bears at heart in making decisions of this sort. We weigh the risk of injury or frustration to any animal against the benefit of social interactions. In the end, we feel it is best for this particular pair not to continue to socialize. In the future, we may revisit this topic when Zhen Zhen’s little brother is old enough to be considered a possible playmate for her.

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

Watch our bears daily on Panda Cam!