National Zoo keepers were alerted to the giant panda cub's death by Mei Xiang's distress call.
The National Zoo has released new video of the moment when giant panda mom Mei Xiang alerted zookeepers that there was a problem with her cub.
The cub died Sunday, just one week after her surprise birth.
In the video, Mei Xiang makes a huffing sound of distress that panda keepers have described as a "honk." It was that unusual sound Sunday morning that led veterinarians to come into the panda's carefully constructed nest and find the lifeless cub.
The Zoo still is investigating the panda's death. Veterinarians said Monday that a preliminary examination found two abnormalities: fluid in the cub's abdomen and an area of hardness in the liver.
Mei Xiang seems to be recovering: Tuesday, she ate her normal diet - bamboo, fruit and biscuits - and drank water, the National Zoo said in a press release Tuesday. Vets are watching her closely and running tests to monitor her health.
However, since her cub's death, Mei Xiang has been seen cradling a toy - a nurturing behavior that she had also shown before the cub's birth. Zookeepers described this as "expression of her natural mothering instinct."
Once she returns fully to her normal behavior and health, the Zoo said, it will reopen the David M. Rubenstein Giant Panda Habitat to visitors.
Before the surprise birth of the cub last Sunday, there had been some talk that the Zoo might return either Mei Xiang or the cub's father ,Tian Tian, to China. However, today the Zoo said that there would be no decision about the pandas' future at the National Zoo "until Mei Xiang’s behavior returns to normal."