ATLANTA - Lun Lun, a 19-year-old giant panda, gave birth to the second of her twins at 8:07 a.m. on September 3, 2016. Her first cub arrived at 7:20 a.m. The cubs, the first giant pandas born in the U.S. in 2016, are the second pair of twins for Lun Lun.
Giant pandas exhibit delayed implantation, and the twin cubs developed from two separate eggs. Following the birth of the first cub, the Zoo Atlanta teams continued to await the arrival of the second cub. Although it is possible for giant panda twins to be born as far apart as days, up until the second cub's birth, there had remained the possibility that the second fetus could be resorbed, or reabsorbed, and would thus not be born. Fetal resorption is not uncommon in giant pandas.
"We're thrilled and relieved that the second of Lun Lun's twins has arrived. While we were aware of the possibility that the two might not be born close together, we were also aware of the possibility that the second fetus could be resorbed, resulting in a failed pregnancy," said Hayley Murphy, DVM, Vice President of Animal Divisions. "Our focus now will be the care and monitoring of the cubs and Lun Lun to ensure that both cubs have the best opportunity to succeed."
Giant panda cubs, which are born nearly hairless, blind and barely larger than a cell phone, are some of the animal kingdom's most fragile newborns, and their early days of life are critical. The Animal Management and Veterinary Teams will employ the same cub-swapping method used with success following the births of the cubs' sisters, Mei Lun and Mei Huan, caring for one cub in a nursery unit while Lun Lun cares for the other. The cubs' time with their mother will be rotated to ensure that both receive equal amounts of maternal care.
Although twins are not unusual in giant pandas, the risk of infant mortality is higher in twins than in single-cub births. In the wild, giant panda mothers who give birth to twins generally care for only one cub, and it is normal in the wild for only one twin to survive. The cub-swapping approach allows the mother to provide care and feeding for both of her offspring without becoming overexerted.
Lun Lun was artificially inseminated on March 28, 2016, and round-the-clock birth watch began on August 22, 2016. Since the time of the artificial insemination, the Animal Management and Veterinary Teams have been conducting regular ultrasounds and monitoring Lun Lun's behavior, as well as monitoring hormone analyses conducted by David Kersey, PhD, an expert in giant panda endocrinology from Western University of Health Sciences.
The cubs are the sixth and seventh giant pandas born at Zoo Atlanta. All of Lun Lun's and Yang Yang's cubs have been the result of artificial insemination. The pair's first three offspring, male Mei Lan (born 2006), male Xi Lan (born 2008) and female Po (born 2010), now reside at the Chengdu Research Base. Their fourth and fifth offspring, females Mei Lun and Mei Huan (born 2013), reside at Zoo Atlanta and are now joined by their younger siblings as the only sets of giant panda twins in the U.S.
Zoo Atlanta Members and guests can expect to meet the cubs in December 2016 or January 2017. Their father, 18-year-old Yang Yang, and 3-year-old sisters Mei Lun and Mei Huan remain in their usual habitats and will not be introduced to the cubs. This separation is normal for giant pandas, which are solitary in the wild.