Download Behavior of the Giant Panda

Behavior of the Giant Panda (Ailuropoda melanoleuca):
Reproduction and Captivity
Tanya Hunter
April 5, 2006
The giant panda (Ailuropoda melanoleuca) is indigenous to the forests of China. Their
populations have been in decline for many years, and they are now considered an endangered
species. Many panda reserves and breeding centers, all located in China, have been created to
protect what is left of their population and to help increase their numbers (WWF, 2006).
Reproduction in the panda is complex, and not much is known about it. This is believed to be
one of the many contributions to the decline in panda populations, as well as to problems in
breeding in captivity. Understanding panda physiology and behavior is crucial for ensuring
reproductive success. The ability to identify a female panda in estrus can increase the probability
of a successful mating. This is helpful for male pandas as well as breeders. Maintaining a
pregnancy is required to ensure the birth of healthy offspring. Once an infant is born, the mother
must adequately care for the young. If she is not able to, then sufficient human intervention is
required. However, pandas have trouble adapting to the presence of humans and captive living
conditions. Pandas in captivity are often physically inactive and stressed, so successful mating is
relatively low (Liu, et al., 2003; Swaisgood, et al., 2003). Continuing research is needed to
improve enclosure conditions and improve the survival of the giant panda.
The diet of the giant panda consists primarily of many different species of bamboo,
although they also eat other plants and sometimes animals, such as fish. Since their digestive
system resembles that of a carnivore, they are unable to digest the plants very efficiently, and as
a result must eat large amounts of it and spend most of the day eating (WWF, 2006). Pandas live
in solidarity, except during mating season. They are seasonally monoestrous, with the mating
season taking place between March and May. During this time, the female may only be fertile for
a few days with spontaneous ovulation (Durrant, et al., 2003). Male pandas will compete for
access to multiple females, a form of mating known as polygamy. After mating, the male will
leave the female and she will raise the offspring alone (Durrant, et al., 2003). Birthing takes
place in the early fall of the next year, from August to November. Usually a female will give
birth to one or two cubs, however, if she does give birth to two she will usually abandon one and
raise the other (WWF, 2006). Newborn cubs are very small and weak. They weigh around 200g
and have very little fur. Infants feed on their mother’s milk (Durrant, et al.; Milius, 2001). A
panda cub will grow at a relatively fast rate, especially during it’s first year, until it reaches
sexual maturity at about 4 - 5 years old. The cub will leave its mother when it is about two years
old (WWF, 2006).
Understanding estrus behaviors and their relationship with estrogen levels is important to
the success of breeders and artificial insemination techniques. During breeding season, females
experience a peak in estrogen levels, after which ovulation occurs. High estrogen levels also
appear to trigger mating behavior, such as scent markings, rear presentations and tail-up display
towards males, and vocalizations such as bleating and chirping. These behaviors can occur at all
times during the year, but during estrus the frequency increases, perhaps to help provide an
indication of fertility. While the increase in these behaviors is triggered by estrogen, they do not
appear to be completely maintained by it, so these behaviors continue for a few days afterwards
as well (Lindburg, et al., 2001).
Knowing when a female is pregnant is essential for developing effective breeding
programs. It can help breeders figure out the most efficient methods of impregnating a female, as
well as what factors are needed for its success. However, it can be difficult to determine if and
when pregnancy occurs in a female panda. After fertilization an egg will remain in the female
reproductive tract for a period of time without implantation. During this time it is speculated that
the development of the embryo is suspended. This is referred to as delayed implantation
(Sutherland-Smith, et al., 2004). Pandas can also experience pseudopregnancy, in which they
express behavioral and hormonal changes similar to an actual pregnancy (Sutherland-Smith, et
al., 2004). As a result of this, the precise length of the gestation period is not exactly known. It is
estimated to be an average of 146 days, but the range can be vast (Sutherland-Smith, et al., 2004;
WWF, 2006). In captivity the estimated range of gestation is between 84 to 160 days (WWF,
2006).
It is believed that, considering their short gestation period, most of the mother’s energy
and resources are spent in the time following birth. This is shown through a relatively
insignificant change in weight during pregnancy, as well as through her rather extreme behavior
after giving birth. Also, if a mother gives birth to twins, she will abandon one, allowing her to
concentrate on raising the other. Newborn cubs are weak and fragile, and depend largely on their
mother for survival. The mother may fast at first, eating and drinking very little as she cares for
her cub. The infant feeds off of its mother’s milk for about a year and a half, further adding to the
stress and demands of the mother (Milius, 2001). Its mother’s milk provides essential nutrients
and proteins, and its composition is unlike other animal (Xuanzchen, et al., 2005). This
information is important for panda cubs raised by humans in captivity, as pandas experience a
substantial amount of growth in the first few years of life (WWF, 2006). As with other
mammals, such as rats, newborns has very little fur and will usually have problems with
thermoregulation, showing behavior similar to ectotherms (Alberts, 1978). Therefore the mother
is also responsible for maintaining the body temperature of her young by holding and covering it
to prevent exposure to the external environment.
However, regardless of this attention and care, pandas in captivity experience high rates
of neonatal mortality, with only about 50% of the offspring living for more than a month (Zhang,
et al. 2000). One issue is that some pandas in captivity will simply refuse to provide any
maternal care for her offspring, leaving human intervention as the only option. This can be
problematic on a number of levels. Firstly, maternal behavior is primarily the response of
hormones released during parturition, but it is maintained through contact and exposure to the
infant. If the cub is separated from its mother, then any attempt to reintroduce them at a later
time will prove difficult, as the mother may then be even more unwilling to accept the child.
Secondly, mother-reared cubs are more likely to exhibit adequate social behaviors as an adult.
This increases their likelihood of contributing more to future breeding programs, and of
surviving if released into the wild (Zhang, et al. 2000).
One instance of a cub being successfully reintroduced with its mother after initially being
rejected was extensively studied (Zhang, et al. 2000). While it is not entirely known which
component of infant exposure is most significant, it has been discovered that a combination of
different stimuli can illicit maternal behavior. Such stimuli includes exposure to infant
vocalizations and urine, at first through a surrogate, toy cub. This eventually lead to holding and
nursing of the cub itself as it was gradually integrated into the mother’s environment. Eventually,
the mother began to display normal maternal behavior towards to the infant. Due to ethical
issues, subsequent studies of this matter will be limited, but this example provides promise and
encouragement that such an issue can be resolved in captivity, hopefully leading to an increase in
offspring survival. This can also be helpful in situations that require human intervention, such as
a twin being abandoned by its mother. However, as pandas do not adapt to the presence of
humans very well, most breeding centers and habitat enclosures strive to keep human interaction
with pandas to a minimum. It is only done under extreme circumstances, and maintaining
maternal care is given the upmost importance (Zhang, et al. 2000).
There are numerous reasons as to why breeding pandas is difficult, particularly in
captivity. For example, while the ova in the panda appear to be normal, the follicles undergo
unusually high amounts of atresia and cysts during development (Liao, et al., 2001). Another
concern is that the pituitary cells can be underdeveloped, resulting in an insufficient amount of
gonadotropins needed for normal reproduction (Liao, et al., 2001). Other problems and concerns
for captive pandas involve their behavior. Pandas have trouble adjusting to captivity. This is
because the environment in the wild is constantly changing, which provides challenges for the
panda as it forages for food and explores the terrain. In captivity, the enclosures are small and
contain little variation, usually consisting of a highly predictable routine. For example, pandas in
captivity do not engage in normal eating behaviors because feedings are controlled by human
caregivers. Food is provided at the same time every day and the panda does not have to work to
acquire it (Swaisgood, et al., 2003). Furthermore, the animals have little or no control over what
occurs around them. Although pandas are solitary, access to other pandas is important. For
example, cubs should remain with their mother until they are ready to leave, and if the mother
cannot raise the cub, then interaction with other cubs is important. Pandas also require the option
of being able to remove themselves from other pandas, which in small enclosures is not always
sufficiently possible (Swaisgood, et al., 2003). As a result of these factors, as well as many
others, captive pandas tend to be highly inactive and may engage in stereotypical behaviors, such
as pacing. Such behavior reflects an inadequate environment and is often accompanied by stress
and poor physiological well-being (Swaisgood, et al., 2003). This can have an immense impact
on reproductive success for pandas in captivity. For example, many males pandas are
uninterested in mating and are often aggressive towards other pandas. Females display weak
estrus behavior and have trouble conceiving (Zhang, et al., 2004).
To help improve the reproductive success of pandas in captivity, measurements need to
be taken to change their environment. One crucial aspect is that the animals must be provided
with choices and variation in regards to food and activities. They must also be given more
control of their surroundings (Swaisgood, et al., 2003). This can be done on a number of ways.
They include: providing larger enclosures with areas of different trees, shrubs and terrain;
changing feeding times and locations; allowing pandas to hear, smell and see neighboring
animals while keeping them in separate inclosures; and providing objects and devices that
require the pandas to work for their food. These methods have proven to decease stereotypic
behaviors and stress, and increase overall activity (Lui, et al., 2003; Swaisgood, et al., 2003).
In an endeavor to protect and maintain the remaining giant panda (Ailuropoda
melanoleuca) populations, knowledge of reproduction and behavior can provide many answers
and solutions. The ability to identify a female panda that is pregnant or in estrus can indicate
which breeding programs are effective. Understanding maternal behavior and being able to
accurately mimic it can help infants survive and remain healthy. As we increase our
understanding of reproductive physiology and behavior, as well as the effect of humans and
enclosures, improvements can be made to maintain the well-being of pandas in captivity.
Literature Cited
Alberts, J. R. 1978. Huddling by rat pups: group behavioral mechanisms of temperature
regulation and energy conservation. Journal of Comparative and Physiological
Psychology. 92 (2): 231 - 245.
Durrant, B. S., Olsen, M., Amodeo, D., Anderson, A., Russ, K. D., Campos-Morales, R., GualSill, F., and Garza, J. R. 2003. Vaginal cytology and vulvar swelling as indicators of
impending estrus and ovulation in the giant panda (Ailuropoda melanoleuca). Zoo
Biology. 22. 313 - 321.
Liao, M. J., Zhu, M. Y., Zhang, Z. H., Zhang, A. J., Li, G. H., Sheng, F. J. 2003. Cloning and
sequence analysis of FSH and LH in the giant panda (Ailuropoda melanoleuca). Animal
Reproduction Science. 77. 107 - 116.
Lindburg, D. G., Czekala, N. M., and Swaisgood, R. R. 2001. Hormonal and behavioral
relationships during estrus in the giant panda. Zoo Biology. 20. 537 - 543.
Liu, D., Wang, Z., Tian, H., Yu, C., Zhang, G., Wei, R., and Zhang, H. 2003. Behavior of giant
pandas (Ailuropoda melanoleuca) in captive conditions: gender differences and enclosure
effects. Zoo Biology. 22. 77 - 82.
Milius, S. The Lives of Pandas. 2001. Science News. 159 (4). 61.
<http://www.sciencenews.org/articles/20010127/bob10.asp>
Sutherland-Smith, M.., Morris, P. J., and Silverman, S. 2004. Pregnancy detection and fetal
monitoring via ultrasound in a giant panda (Ailuropoda melanoleuca). Zoo Biology. 23.
449 - 461.
Swaisgood, R. R., Ellis, S., Forthman, D. L., and Shepherdson, D. J. 2003. Commentary:
improving well-being for captive giant pandas: Theoretical and practical issues. Zoo
Biology. 22. 347 - 354.
World Wide Fund for Nature. Panda Central: Panda Q & A. WWF China. March 22, 2006.
<http://www.wwfchina.org/english/loca.php?loca=75#5>
Xuanzhen, L., Mingxi, L., Jianqui, Y., Zhihe, Z., Xiangming, H., Jingchao, L., and Zhi, Y. 2005.
Composition of captive giant panda milk. Zoo Biology. 24. 393 - 398.
Zhang, G. Q., Swaisgood, R. R., Wei, R. P., Zhang, H. M., Han, H. Y., Li, D. S., Wu, L. F.,
White, A. M., and Lindburg, D.G. 2000. A method for encouraging maternal care in the
giant panda. Zoo Biology. 19. 53 - 63.
Zhang, G., Swaisgood, R. R., and Zhang, H. 2004. Evaluation of behavioral factors influencing
reproductive success and failure in captive giant pandas. Zoo Biology 23. 15 - 31.