Giant Panda Cub Bei Bei Marks Big Milestone

Blink, blink: The National Zoo announced Tuesday that Bei Bei, their celebrated Giant Panda cub, is opening his eyes.

Here’s their special news, delivered in a tweet:

“Bei Bei’s eyes are now partially open & teeth buds are developing. Weighing in at 4.5 lbs. of adorable. #PandaStory”

Six-week old Bei Bei, born Aug. 22, will eventually weigh about 250 pounds, according to the National Zoo.

The giant panda is listed as endangered in the World Conservation Union’s (IUCN’s) Red List of Threatened Species. There are about 1,600 left in the wild. More than 300 pandas live in zoos and breeding centers around the world, mostly in China.

It’s kind of surprising how small giant pandas are when they’re born. Except for a marsupial (such as the kangaroo or opossum) though, a giant panda baby is the smallest mammal newborn relative to its mother’s size, the zoo notes.

Cubs do not open their eyes until they are six to eight weeks of age and are not mobile until three months. A cub may nurse for eight to nine months. A cub is nutritionally weaned at one year, but not socially weaned for up to two years.

In addition to opening his eyes, Bei Bei recently got a tour, with his mama Mei guiding him, of the ”big room” outside the little den where they usually hang out: