New Clues Found On Why Giant Pandas Are Born Tiny
Wed, April 21, 2021

New Clues Found On Why Giant Pandas Are Born Tiny

Giant pandas, with their unique black and white coat, are adored in different countries and treated as a national treasure in China / Photo by: Fernando Revilla via Wikimedia Commons

 

Giant pandas, with their unique black and white coat, are adored in different countries and treated as a national treasure in China. A full-grown giant panda stands between 2 and 3 feet tall at the shoulders and reaches 4 to 6 feet long. Males usually weigh up to 250 pounds and are larger than females, according to the Smithsonian's National Zoo. 

However, pandas are born so tiny with an average weight of only 0.2 pounds or 1/900 of their mother’s original weight compared to 1/20 for human newborns and mothers. Experts believe that it is a breeding strategy for why pandas have a small birth size. Some believe that it is because pandas rely almost entirely on bamboo that has low nutritional value. 

 

Decade-Old Theory: Pregnancy Overlapping Hibernation

The decade-old theory has also associated the low birthweight to a panda’s hibernation. The theory is that a mother panda’s pregnancy overlaps with her winter hibernation. This is why pregnant pandas don’t drink or eat during this time and the baby would rely mostly on the mother’s fat reserves to survive. This also caused the breakdown of muscle to supply the amount of protein needed by the fetus.

A team of researchers from Duke University in North Carolina recently found new clues as to why giant pandas are born so tiny. They believe that the decade-old theory is unlikely to be true because they didn’t find significant differences in the bone growth of hibernating bears to their counterparts that remain active and did not fast during the mother’s pregnancy.

The researchers added that although pandas are born small, their skeletons are just as mature during birth as their close animal cousins.

The decade-old theory has also associated the low birthweight to a panda’s hibernation. The theory is that a mother panda’s pregnancy overlaps with her winter hibernation / Photo by: 995645 via Pixabay

 

The Quirk of Giant Panda Pregnancy: Delayed Implantation

Peishu Li and Kathleen K. Smith from the Department of Biology believe that the factor that pushed giant panda babies to have a small size is the quirk of the mother’s pregnancy. They explained that all bears, including pandas, experience what they refer to as delayed implantation. The moment the egg is fertilized, it will undergo a suspended animation and will float in the mother’s womb for several months before it will be implanted in the uterine to resume development and finally be ready for birth.

Other bears gestate two months after the implantation but pandas gestate in one month. This means that baby pandas are “undercooked,” Li said. Smith also said that pandas’ development is “cut short.”

The duo went on to explain that they have only focused on the bears’ skeletons for their research and other organs, such as the brain, may have a different explanation for future research. For now, they can say that baby pandas have the same trajectory as other mammalian relatives, which means that their bones also mature at the same rate and sequence but just on a shortened timetable.

Other scientists also continue to search for a complete explanation of baby pandas’ peculiar size and how they evolve. Smith said that they need more insights about reproduction and ecology in the wild and they may not have enough time, considering the risk of the animals’ extinction. Somehow, their study puts scientists a step closer to finding their answers.

The researchers said that their work was supported by the Undergraduate Research Office at Duke, the Department of Biology, and the Shared Material Instrumentation Facility Undergraduate User Program grant.

A Panda’s Growth Process

China travel agency China Highlights mentioned that when a panda is already one week old, black patches will begin to appear on its skin and black hair will begin to grow around its ears and eyes. At three weeks old, the black markings will be fully apparent and its eyes will open and it will also begin to crawl. At three months old, its hearing will improve and can already walk a yard. At six months, it will start to eat bamboo. By the time it reaches one year old, it will weigh 88 pounds. At two years old, they leave their mothers to begin fending for themselves.

Conservation Status: Endangered to Vulnerable Species

Endangered species conservation organization the World Wildlife Fund has published that wild pandas have been upgraded from the endangered label to vulnerable. This category means that they are likely to become endangered unless circumstances that threaten their reproduction and survival will be improved. 

WWF-China has been preventing habitat loss to protect the wild pandas. They worked with partners to preserve and protect their critical habitat not just for them but for other species as well, including snow leopards, takins (gnu goats), and snub-nosed monkeys.

After years of conservation work, their efforts yielded success. The numbers of wild pandas are finally rebounding. The International Union for Conservation of Nature, the governing body of protected sites working in the field of nature conservation, declared in September that pandas are now on “vulnerable” status after a population growth of nearly 17% in the last 10 years. WWF-China’s CEO Lo Sze Ping, however, reminded the public that the change in the status is encouraging but it does not mean that the pandas are out of the woods already. Much of their habitats are still threatened today because of poor planning of infrastructure projects. So far, they’ve counted only 1,864 pandas in the wild.

It is still a long way to go, but the change in panda status is an encouraging sign that maybe finally, humans are starting to really value the gifts of nature.

Endangered species conservation organization the World Wildlife Fund has published that wild pandas have been upgraded from the endangered label to vulnerable / Photo by: Cliff via Flickr