A newborn giant panda weighs 3 to 5 ounces and is about the size of a stick of butter, according to the Smithsonian’s National Zoo. It’s pink, hairless and blind, and roughly 1/900th the size of its mother. Other references put the birth weight at 90 to 130 grams and the ratio at about 1/800 of the mother’s weight.
Either way, it’s the most extreme size difference between mother and newborn of any placental mammal.
Newborn compared to adult #
| Newborn cub | Adult giant panda | |
|---|---|---|
| Weight | 3 to 5 oz (90 to 130 g) | Males up to 250 lb (113 kg); females rarely over 220 lb (104 kg) |
| Length | Roughly the size of a stick of butter | 4 to 6 ft (1.2 to 1.8 m) |
| Coat | Pink, hairless | Black and white |
| Eyes | Closed | Open |
| Can it move? | Barely | Fully mobile |
To put the ratio in human terms: a 140-pound woman giving birth at 1/900th of her weight would have a baby weighing about 2.5 ounces. A human newborn is closer to 1/20th of its mother’s weight.
Why panda cubs are born so small #
The short answer is that a panda cub does most of its developing after birth rather than before it.
The Smithsonian’s National Zoo gives the gestation period as 90 to 180 days, and that enormous range is the clue. The embryo doesn’t begin developing as soon as mating happens. It floats freely before implanting in the uterine wall, and only then does growth begin in earnest. The actual period of fetal development is short, often a matter of weeks, which is why the total from mating to birth varies so much between individuals.
Bears in general do this, and there are reasonable theories about why it suits a panda in particular. A mother living on bamboo has no fat reserves to spare, so carrying a large fetus through winter would be expensive in a way her diet can’t fund. Producing a tiny, undeveloped cub and feeding it milk afterwards spreads that cost out.
The result is a cub that arrives essentially as a fetus: no fur, no sight, no ability to regulate its own temperature, and entirely dependent on a mother who is more than nine hundred times its size. The black and white markings appear as the fur comes in over the following weeks, which is why photographs of very young cubs look nothing like a panda.
How big does a panda get? #
Adults are proper bears. The Smithsonian’s National Zoo puts them at 2 to 3 feet tall at the shoulder and 4 to 6 feet long, with males weighing up to 250 pounds in the wild and females rarely reaching 220 pounds.
Getting there takes a long time on a diet of bamboo, which makes up about 99% of what a giant panda eats and delivers so little usable energy that adults spend 10 to 16 hours a day feeding. What do pandas eat covers the numbers and why the animal’s carnivore digestive system makes the volume necessary.
How long do pandas live? #
The Smithsonian’s National Zoo gives about 15 to 20 years in the wild and around 30 years for pandas in zoos. Roughly 600 giant pandas live in zoos and breeding centres worldwide, against a wild population of around 1,900. The wild figure and what it means for the species is covered in are giant pandas still endangered.
Watching cubs grow #
Panda cubs are one of the few wildlife subjects where you can genuinely watch the development yourself. Zoos with breeding programmes document births in detail and several run live cameras, and their own pages are the right place to check specific milestones like when eyes open or when a cub first walks, since those vary between individuals and get recorded case by case.
The Smithsonian’s National Zoo and the zoos in Chengdu, Chongqing and Ya’an publish some of the most thorough records. Anything you read about cub development that doesn’t name a source is probably copied from one of them, several steps removed.
The size progression is also, it turns out, the basis of a puzzle game. Merge Panda is a free drop-and-merge game where snacks stack in a bamboo crate and two of a kind merge into the next size up, through eleven tiers. The last three are a Panda Cub, a Mama Panda and an Emperor Panda, each physically larger on the board than the one before, which is the one part of panda biology it gets exactly right.
Frequently asked questions #
How much does a newborn giant panda weigh? #
3 to 5 ounces, according to the Smithsonian’s National Zoo, or 90 to 130 grams in other references. That’s about the weight of a stick of butter, and roughly 1/900th of the mother’s size.
Why are panda babies so small compared to their mothers? #
Because most of their development happens after birth. The embryo implants late and grows for only a short period before delivery, so the cub arrives undeveloped and is fed on milk instead. A mother subsisting on bamboo has little spare energy to invest in a long pregnancy.
Are panda cubs born black and white? #
No. They’re born pink, hairless and blind. The black markings appear as the fur grows in during the first weeks of life.
Do giant pandas have twins? #
Twin births do occur in giant pandas. How often, and how zoos and breeding centres manage them, is documented by the institutions that handle those births, so the Smithsonian’s National Zoo and the Chinese breeding centres are the places to read about it rather than secondhand summaries.
How long do giant pandas live? #
About 15 to 20 years in the wild and around 30 years in zoos, per the Smithsonian’s National Zoo. The difference is what you’d expect: no predation, veterinary care and a reliable supply of bamboo.
How fast do panda cubs grow? #
Very fast in relative terms, since they start at a few ounces and reach adult weights in the hundreds of pounds. Exact growth curves differ between individuals and are tracked by the zoos raising them, which publish cub weights as they go.