Given the dangerously low numbers and low birth rate of giant pandas in the wild, captive breeding programs are essential if we are to sustain the Panda population. Attempts to breed pandas in captivity in China began in 1955, but it was not until eight years later, on September 9 in 1963, that Ming Ming the first ever captive-bred giant panda, was born at the Beijing zoo.
Since then, there have been many advances in breeding programs and in our knowledge of Panda mating cycles and behaviors, pregnancies, and the rearing of captive born cubs.
While captive breeding programs are essential to the survival of the species, getting pandas to mate and raise healthy cubs in captivity is often a complex process.
Early in their efforts, scientists working on captive breeding of pandas realized that there were substantial difficulties in getting the bears to mate naturally. They either lost interest in mating the natural way or simply did not know how. Behavioral research has provided information that has increased the success rate of natural mating.
In addition to the challenges in getting pandas to mate, timing is everything — and it is working against them. A female panda has a single estrous cycle once a year, in the spring, for 2 to 7 of those days, and she’s only actually fertile for 24 to 36 hours. That is a TINY window of opportunity. Many times scientists are forced to rely on artificial insemination procedures.
Years of study have given researchers and veterinarians a wealth of knowledge regarding the female panda’s estrous cycle. Identifying the “perfect time” to perform artificial insemination is much more precise today with advanced medical technology and knowledge about hormone levels and behavioral clues. Female pandas are closely monitored as they approach their fertile season and urine testing confirms optimal hormone levels. During the procedure, the pandas are sedated and a fresh semen sample is obtained from the male (thawed frozen semen can also be used). The semen is then inserted into the female with hopes for a successful fertilization. The procedure is relatively non-invasive and most pandas are “back to normal” within a few hours.
Unfortunately, neither artificial insemination nor natural mating will guarantee a pregnancy, and veterinarians must simply wait (and wait….and wait) before they know for certain that a panda is truly pregnant. As with all aspects of panda mating, determining if a panda is pregnant is complicated. Like many other species, pandas experience embryonic diapause, in which the embryo is fertilized, but not yet implanted in the uterine wall. The offspring can’t continue to grow until it has implanted, so while the gestation period is around 50 days, some panda pregnancies can stretch out to more than 160 days because of diapause.
If diapause doesn’t make pregnancy confirmation difficult enough, female pandas can also experience pseudopregnancy—they aren’t actually pregnant, but exhibit the same behaviors as pregnant pandas (decreased appetite, sluggishness, and even similar changes in hormones). It’s almost impossible to distinguish between the two since panda fetuses are often too small to be spotted on an ultrasound. It is often not until a baby panda is actually born that the pregnancy is confirmed.
A baby panda is born blind, almost hairless, and only about the size of a stick of butter (or 1/900th the size of its mother). These fragile cubs can easily get sick and die. Fortunately, again with advances in knowledge and technology, at breeding centers 90% of baby pandas can survive (compared to no more than 30% in the 1960s).
Female pandas often give birth to twins, but can only effectively care for a single cub. In the wild, this means that one of the cubs is simply left to die. Fortunately, at breeding centers, researchers help the mother pandas to take care of the cubs, thus helping to ensure the survival of both. Cubs are essentially “swapped out” with the mother so that they are both receiving her care. During the time that the cubs are away from mom, staff members serve as surrogate mothers feeding and caring for the newborn cubs. Time in the nursery is also a valuable tool for the veterinary staff to monitor the progress of the cubs making sure they are developing at the proper rate.
Despite all of the challenges of breeding Pandas in captivity, the past 20 years have seen dramatic increases in the number of successful captive births. Much of this success comes from the development of behavioral management strategies, guided by the application of scientific knowledge. There are over 600 pandas now in captivity which is considered to be a very good number for sustaining the population.
For more detailed studies on Captive Breeding in the Giant Panda:
Zhang, G., Swaisgood, R. R. and Zhang, H. (2004), Evaluation of behavioral factors influencing reproductive success and failure in captive giant pandas. Zoo Biol., 23: 15–31. Link to Article
Snyder, N. F.R., Derrickson, S. R., Beissinger, S. R., Wiley, J. W., Smith, T. B., Toone, W. D. and Miller, B. (1996), Limitations of Captive Breeding in Endangered Species Recovery. Conservation Biology, 10: 338–348. Link to Article
Owen, M. A., Swaisgood, R. R., Czekala, N. M., Steinman, K. and Lindburg, D. G. (2004), Monitoring stress in captive giant pandas (Ailuropoda melanoleuca): behavioral and hormonal responses to ambient noise. Zoo Biol., 23: 147–164. Link to Article
Swaisgood, R. R., Lindburg, D. G. and Zhang, H. (2002), Discrimination of oestrous status in giant pandas (Ailuropoda melanoleuca) via chemical cues in urine. Journal of Zoology, 257: 381–386. Link to Article
McGeehan, L., Li, X., Jackintell, L., Huang, S., Wang, A. and Czekala, N. M. (2002), Hormonal and behavioral correlates of estrus in captive giant pandas. Zoo Biol., 21: 449–466. Link to Article
Kleiman, D. G. (1983), Ethology and Reproduction of Captive Giant Pandas (Ailuropoda melanoleuca). Zeitschrift für Tierpsychologie, 62: 1–46. Link to Article
