Behavioral and Hormonal Consequences of Transporting Giant Pandas from China to the United States
It is well recognized that transportation, which involves an abrupt and dramatic change in environment, is a common cause of animal distress. Yet transfers between institutions are one of the primary tools of captive animal management. Transfers of giant pandas between institutions in China are becoming more frequent as breeding recommendations to increase genetic diversity are followed. Furthermore, several pandas have been transferred internationally as part of the giant panda loan program. This study evaluated the effects of transporting giant pandas from China to the United States by measuring behavior and urinary cortisol.
This study was a collaborative effort among Zoo Atlanta, Smithsonian’s National Zoological Park (SNZP), and the Zoological Society of San Diego (ZSSD). Subjects were pandas loaned to Zoo Atlanta and SNZP. Both SNZP and ZSSD assayed urinary cortisol and assisted with interpretation of results.
The Zoo Atlanta (ZA) female’s (Lun Lun) urinary cortisol was highest in the sample collected on the plane from Beijing to Atlanta and in the sample collected her first day in Atlanta. By her second day in Atlanta, Lun Lun’s cortisol levels had dropped substantially. For Lun Lun, initiating contact with a conspecific was significantly positively correlated with cortisol concentrations, indicating that she established contact with the male more frequently when she experienced her strongest endocrinological stress response. The ZA male’s (Yang Yang) urinary cortisol pattern was different from the female’s. He displayed a peak in cortisol concentration on his second day in Atlanta. Then he exhibited declining values before his highest peak, which occurred 28 days after transport. For Yang Yang, a significant negative correlation was found between locomote and cortisol concentration, indicating that he spent less time locomoting when experiencing his strongest endocrinological stress response. Smithsonian’s National Zoological Park (SNZP) female (Mei Xiang) exhibited a highly variable urinary cortisol profile. Although her cortisol concentration was relatively high in the first days after transport, she had higher cortisol levels eight times throughout the 30 days after transport. The NZP male (Tian Tian) displayed a peak in urinary cortisol the day after transport. His cortisol levels decreased substantially within a few days but still remained variable with the second highest value occurring 15 days after transport. For the NZP subjects, no significant correlations were found between behavioral and cortisol measures.
All subjects displayed significant changes in behavior during the month after transport. Lun Lun exhibited a significant reduction over time in play initiation. Yang Yang exhibited significant increases over time in approach and contact conspecific. He also displayed a significant reduction in resting. Tian Tian displayed a significant increase in affiliative behavior and feeding, whereas he rested and groomed less. Mei Xiang also groomed significantly less over time.
No common pattern was found in the behavioral and endocrinological responses across the subjects. Although the sample size was too small to statistically test for sex differences, some interesting intrasexual similarities emerged. Both females displayed less overall change in behavior and cortisol between pre-transport and post-transport conditions compared to the males. After transport, both males locomoted less, rested more, and displayed greater fluctuation in absolute cortisol values than did the females. In the month following transport, both males displayed increased social behavior and reduced resting.
It is important to recognize that, although the subjects displayed an endocrinological stress response to transport, they adapted fairly rapidly to their new environments and have done well since that time. None of the subjects demonstrated any long-term consequences indicative of chronic stress, such as suppression of growth or immune function. On the contrary, all subjects have gained weight and are in good health.