The surviving specimen of the two giant panda cubs born last Saturday at the National Zoo is male, and was fathered by the zoo’s resident adult male bear, Tian Tian. While zoo staffers are still elated to have another panda cub in their mix regardless of the parentage, the results of the paternity test reject the zoo’s attempt earlier this year to increase the species’s genetic diversity by inseminating the adult female panda, Mei Xiang, with sperm collected from a male bear living in China.
“We don’t have enough background,” said Pierre Comizzoli, a Smithsonian research biologist, to determine how Tian Tian’s sample overcame the imported stuff. “But fresh sperm is better.”
The cub that died Wednesday was also a male born of Tian Tian’s semen, the zoo announced Friday. Zoo officials believe it succumbed to pneumonia developed after aspirating on formula that lodged in its respiratory system while on a feeding tube.
Mei Xiang gave birth to her fifth and sixth cubs on Saturday. Because female pandas tend to only mother one cub at a time, the zoo’s veterinary staff attempted to swap the two cubs between Mei Xiang’s care and laboratory feeding and observation. Eventually, the swapping became difficulte as Mei Xiang refused to let go of the healthier cub, leaving the smaller one in the zoo staff’s possession.
“All indications were that it was fine except it was two-thirds the size of its brother,” said the zoo’s chief veterinarian, Don Neiffer.
But aside from glimpses on the National Zoo’s live cameras and social-media accounts, the public won’t see much of the surviving cub until at least January. Not that there’s much to see. The cub, while plenty vocal, currently weighs 163 grams and looks more like a fuzzy, pink splotch of rubber than the black-and-white bear it’ll grow up to be.
The new cub will also make the panda exhibit a bit crowded for a while. The habitat is capable of supporting four bears, meaning it will be fully booked until 2017, when Bao Bao, the female cub born in 2013, is sent to China, which legally owns all giant pandas everywhere. (Pandas born in US zoos are denied birthright citizenship, a caveat that should meet with President Trump’s approval when it’s time to send Bao Bao home.) Until 2017, the pandas will have to deal with cramped quarters, especially Mei Xiang, who currently enjoys twice as much indoor space as the others, said Brandie Smith, who oversees the pandas’ care.
Don’t expect any panda family holiday cards, though. While this new cub is a full sibling of both Bao Bao and Mei Xiang’s and Tian Tian’s first cub, Butterstick (d/b/a Tai Shan), it will almost certainly never cross paths with its older sister. Pandas are solitary creatures in the wild, and the National Zoo tries to mimic that environment as closely as possible. There are a few incidents of zoos allowing sibling pandas to cross paths, and the results are not good—think fighting and inbreeding.
“The siblings won’t hang out together,” Smith said.