To Breed or Not To Breed, part 2
Posted at 8:05 am May 19, 2006 by Suzanne HallRead To Breed or Not To Breed, part 1 here.
We know that female pandas are able to get pregnant on a yearly basis, as happens frequently in China in captivity when animal managers remove dependent offspring to terminate the lactational suppression of estrus. Once cubs are removed, the female panda is free to cycle again and breed. Many of the adult females will give birth nearly every year of their reproductive lives, from about age 5 through 17.
Is this constant process of gestation, birth, and cub rearing hard on the panda dam? Perhaps. In the human, having multiple births too closely spaced is correlated with increased rates of premature birth. It is hypothesized that this is due to the inability of the maternal body to replenish nutrients in between pregnancies if time is too short. We do not yet know, however, if this is the case for the panda.
It can be said, however, that year after year the female pandas are able to give birth and rear their young. Wolong has a nearly 100% survival rate among its cubs born in the last few years. And in 2000, one female, named " Number 1," gave birth to three cubs, despite having had cubs several years in a row. All of this suggests that the females are physiologically able to cope with the demands of such a captive breeding program.
Perhaps one advantage of a yearly breeding cycle is that it helps the female replenish herself. At the six-month mark, when her dependent young are removed, the cubs are getting quite large and developing quickly. At this point, the young are not yet feeding on bamboo, and rely exclusively on their mothers to meet their nutritional needs. The lactational drain produced by such a cub must be quite significant. However, once the cub is removed, this drain is gone and for a period of months the panda female is free to rest and feed without the constraints of caring for offspring. This may be all she needs to recharge her batteries for the next go-around. One of the blog readers hypothesized that the energetic demands of lactation may be more significant than those of gestation and birth, and for the panda this may very well be true.
What of the cubs once they are removed? Are they harmed by this regime? You may know that the cubs are placed in a communal housing arrangement in which they are able to interact with other cubs of the same age. This experience certainly helps to allow for the social contact needed by the cubs in the early months of life. Although we have not yet completed any studies to quantify the difference between a mother-raised and a peer-raised cub, we can say this: the peer-raised cubs have grown up to breed and mother their own offspring competently. That is a significant statement about their skill set and their mental wellbeing.
The net effect of a yearly breeding cycle is that the population of captive pandas in China has skyrocketed. In the early 90s, the population of Wolong was not sustainable: deaths outnumbered births. Now, they add large numbers of cubs every year (with 17 born in 2005!). As the captive population serves as a buffer for the wild one, an insurance policy against extinction, there are many good things to be said about such a birth rate. However, unless significant numbers of animals are reintroduced to the wild or are located in other facilities worldwide, it is unlikely that the infrastructure of these captive facilities can tolerate such a population growth endlessly. There may yet come a day in which the managers of panda populations within China feel it is in the best interest of the bears to slow the birth rate by returning to a biennial birth schedule. This change will not likely come before Su Lin is added to the breeding population in China, but perhaps her offspring will be subject to a birth schedule that more closely mirrors that of their wild brethren.
Suzanne Hall is the senior research laboratory technician for the San Diego Zoo's Office of Giant Panda Conservation.
You can follow any responses to this entry through the RSS 2.0 feed. Scroll to the end to leave a comment. Pinging is not allowed.
May 19th, 2006 at 8:16 am
it does seem that yearly breeding without adequate facilities (in the wild or in captivity) is poor planning. if the panda is endangered due to loss of habitat, adding more pandas to the shrinking habitat cannot be good for them. but it is wonderful to observe them- as adults and as growing cubs.
May 19th, 2006 at 10:53 am
Is it a possibility that Su Lin and Tai Shan will be able to mate, because I assume they will both be back at Wolong at the same time?? And these pandas that are all kept together: will that cause problems when they are set out on their own? From what I have read, the panda is a solitary animal. Do you think this will effect them later down the road?? When Su Lin returns to Wolong will she find it hard to settle in when she was trained here by certain keepers?
Editor's note: Su Lin and Tai Shan are actually related to each other! The NZP adult male Tian Tian, father of their cub, is a half brother of our very own Bai Yun. Their father, Pan Pan, is one of the most successful captive breeding males ever at the Wolong Nature Reserve in Sichuan, China.
May 19th, 2006 at 11:03 am
Isn't there also a financial element at work here that may be given precedence over the welfare of the panda mothers? The Chinese Government receives millions of dollars from foreign zoos for the the loan of pandas, so increasing the number of cubs increases the potential revenue. I hope Wolong is not little more than a panda mill.
May 19th, 2006 at 12:56 pm
I guess what all this really boils down to is that we are all deeply concerned about the health, welfare and happiness of our precious Hua Mei.
May 19th, 2006 at 2:15 pm
I think the question becomes " How far do we dare deviate from 'natural' Panda breeding in order to save the species from extinction?"
As I opined in previous comments, these bears belong to China. They ARE a source of revenue to that country, but if America and other wealthy countires are willing to pay for the privilege of leasing these beautiful bears, and if the money goes toward saving Pandas and their habitat, then I believe it's money well-spent.
Here in America we have taken extraordinary steps to save the California condor from extinction, up to and including removing eggs from nests to hatch and hand-raising the chicks to encourage the adult birds to lay another clutch. We actually caught the few wild condors that were left, caged them (In large, free-flight cages), and did everything we could to turn them into baby-making machines. And those extraordinary steps have worked, though the 270 birds now living are highly inbred. But condors are soaring free again and are breeding in the wild.
I would think that the lessons we learned from the condor program- both the failures and the successes - are being applied to save the Pandas. China is trying, with extremely limited resources, to preserve and increase wild Panda habitat. Wolong and other facilities are struggling to increase the Panda population while preserving enough genetic variability to ensure that any released bears will have a fighting chance to survive in the wild.
Sure, it tears at my heart to see cubs removed from their mothers before the natural time for
weaning. And to think of Hua Mei and Mei Sheng and Su Lin and Tai Shan going back to China to become baby-makers. But it is their destiny to do their part to save their species, whatever that destiny requires of them. There is solace in knowing that so many people around the world care deeply about these Pandas, and that people like the SDZ Panda team and the folks at Wolong are doing their best to ensure that while the bears are fulfilling their destiny, they are as healthy and as content as possible.
I guess what I am saying is that I would rather see ten generations of Pandas raised under " unnatural" circumstances than someday see the sad announcement that the last living Panda has gone from the world forever.
May 19th, 2006 at 2:56 pm
With all the information about Wolong and its successful breeding program, I'm curious about your beloved Shi Shi. I know he was getting on in years. Is he still alive and if so, is he healthy?
May 19th, 2006 at 4:11 pm
What a great photo of Bai Yun and Su Lin in the snow!
I hope there are plenty of trees around in China for Su Lin to escape to.
Will our boy, Mei Sheng, be going to China in August or September? If so, will one of his caretakers be able to travel with him to lessen the stress of the transition?
May 20th, 2006 at 10:24 am
Pamela G. said it so well. Trying to save the species is the key to many decisions that are being made right now. The panda research is as humane as possible and those involved that I have met have cared deeply about ALL the pandas. We don't really know, yet, what effect these efforts will have, but the scientists are monitoring things very carefully, to learn and to improve what they are doing.
In Wolong, when we met with Ron Swaisgood from the SDZ, I was very impressed with how much he understands and how concerned he is about the welfare of the bears and about not causing harm. He said the cubs, for example, are doing very well by being with one another in the Kindergarten, which helped him to see that their socialization actually benefitted by their interaction with the other cubs. He has introduced ideas for enrichment practices that appear to be working very well. That includes introducing new " toys" and activities and rotating these frequently to provide positive stimulation for the cubs. From what I observed, I would say it is turning out to be quite successful.
Yes, there is a " price" to pay, but so far, I think it is worth it, from what I have learned from our 2006 Panda Tour in China.
May 20th, 2006 at 5:46 pm
Thank you, Suzanne, for explaining the reasoning behind allowing the pandas to produce cubs yearly. It's clear the humans who work with pandas care deeply for them, so we have to trust the captive pandas are not being unduly harmed in the efforts to preserve them.
May 22nd, 2006 at 6:27 am
I heard on a radio news report a few days ago that for the first year in many, many years, the bamboo forests of Sizchuan Province are actually on the increase, since new laws have been passed against deforestation. So as the pandas themselves are being bred in captivity, with the idea that some may one day be released into the wild, it looks as if more " wild" may be available to them. Maybe not enough - maybe not yet - but maybe a turning point of some sort has been reached.
May 22nd, 2006 at 8:20 am
What a pleasure just now to watch beautiful Momma Bai close up, resting on a branch.
May 22nd, 2006 at 11:19 am
Once again thank you, Suzanne, for the great information about our favorite bears.
May 22nd, 2006 at 1:27 pm
Thank you again for another informational entry. I too was concerned about the growing captive population in China, as space for the bears does not expand as quickly as the number of residents. With the laws protecting the giant panda's natural habitat, it should be difficult to increase captive grounds. Certainly a happy medium between captive breeding and reintroduction is optimal… but would researchers consider the fight against extinction a success if there were only pandas in captivity remaining?
Back in SD… it's nice to see Mei Sheng on the pandacam again!
May 22nd, 2006 at 5:29 pm
Annie #13,
I think most researchers would agree that it is a heartbreaking tragedy whenever the last member of any species is gone forever. True extinction is a depressing state for any conservation-minded person to consider. But extinct in the wild isn't much better, given our human species' propensity to make the wild habitat situation worse, not better. Sure, there are some exceptions to this rule, and a few success stories to boot (the Arabian oryx comes to mind), but usually it's hard to reverse the trend once no animals are left in the wild. Let's hope the panda never faces that dismal predicament.
That said, so long as there are individuals in managed care facilities - and the panda benefits from a now robust and thriving captive population - there is always hope for a repatriation should the wild population cease to exist. And so long as there is hope, there will be people out there working to see that hope realized.
May 24th, 2006 at 6:31 am
i read that Hua Mei is pregnant again. can anyone from sdz confirm that? i wonder if she is, is she is going to have another set of twins………..lol poor mommy.
May 24th, 2006 at 8:12 am
The video of Bai Yun, Su Lin and brown bear friend in the snow is glorious; the shots of the visitors reinforce what I've always thought - look at a bear and you can't help but smile! Pandas particularly; I don't know what it is about them, but they are instant sunshine and should be available on prescription!! Thanks for sharing the video.
May 24th, 2006 at 12:18 pm
Elly #15,
If Hua Mei is indeed pregnant again, it is far too soon to confirm it. We know that she bred successfully in April at Wolong, and in all likelihood she could be pregnant. She may be showing some signs of pregnancy, but such signs don't actually confirm pregnancy, due to the panda phenomenom of " pseudopregnancy." The earliest an ultrasound has confirmed pregnancy is a few weeks prior to birth, and it's too early for that in Hua Mei's case.
Anyone who is willing to go on record as saying she is definately pregnant at this point is rather bold. We have to just wait and see.
May 24th, 2006 at 1:24 pm
An Interview with Su Lin (No. 3)
Reporter: " Good Evening, Su Lin.â€
Su Lin: " Hello! I "member you! We talked before, when I was very little.â€
R: " That's right. And you are getting bigger every day.â€
S: " Mother says I'm a growing girl, so I must learn to eat bamboo and other crunchy things…but I still like milk and frooties best.â€
R: " Fruitsicles?â€
S: " 'Frooties' is easier to say.â€
R: " OK. Did your mother talk about Panda Home and the Panda Dream today?â€
S: " No. But she said that once she made a Long Jour-ney – did I say that right? – and so did my sister. What is a Long Jour-ney?â€
R: " It means that you go far, far away.â€
S: " Like when I climb my trees?.â€
R: " I think a Long Journey is a lot farther than that.â€
S: " Oh my! Well, Mother says that my brother will make a Long Jour-ney, and someday so will I. I telled….told her I would like that if there are trees to climb….and good things to eat.â€
R: " What did she say?â€
S: " She called me "Miss Smarty-Paws'! Mother only calls me that when I do something good. Like when I sang her my climbing song.â€
R: " You make up songs? Will you sing your climbing song?â€
S: " Pandas make songs about lots of things:
Hold with my paws
Grab with my claws
Up in the tree
Nothing sees me
High in the air
BIG Panda bear!â€
" I'm making a song about frooties, but nothing goes with "frooties'.â€
R: " Ummmmm….how about "fruitsicle' and "tummy tickle'?â€
S: " Oh my! I must go tell Mother! Thank you!â€
R: " Thank YOU, Miss Smarty-Paws Su Lin.â€
May 24th, 2006 at 4:00 pm
Oh Pamela G…that's adorable!
I love your Su Lin interviews… Can't wait to hear her 'frooties song'. 
May 24th, 2006 at 5:50 pm
Pamela G (#18)
Thank you so much for the great " interview with Su Lin (No.3)" .
I know it will bring smiles to a lot of panda lovers.
May 24th, 2006 at 10:47 pm
Yes, thanks Pamela G. for reporting the interview with Su Lin. It sounds just like her. I'll bet she went skipping off to tell her mother a new poem about those " frooties."
May 25th, 2006 at 9:16 am
Pamela G.–Thanks for another lovely interview with Princess Su Lin. It's so enjoyable to read them. Especially loved her poem.
May 27th, 2006 at 9:51 am
Pamela keep those interviews coming, I love 'em!
January 17th, 2007 at 12:55 pm
I'm doing a project at school on giant pandas and am unable to find out if any have been released back in to the wild which have been bred in captivity to try and help the population.Thank you for your help, James
Moderator's note: Read this blog about a captive-born released panda: http://www.sandiegozoo.org/wordpress/general/going-home/
April 22nd, 2008 at 2:18 am
LOVE PANDA