09-23-2012 - The giant panda cub born a week ago at the National Zoo in Washington died Sunday morning, saddening zoo officials and visitors who had heralded its unexpected arrival.

The 4-ounce cub, about the size of a stick of butter, showed no obvious signs of distress and made its final recorded noise shortly before 9 a.m. Sunday, zoo officials said at a news conference.

The cub's mother, Mei Xiang, then made an unusual honking sound at 9:17 a.m. that her keepers interpreted as a distress call, and she moved away from where she had been nesting with the cub. About an hour later, one keeper distracted her with honey water while another used an instrument similar to a lacrosse stick to pick up the cub.

The cub, whose gender could not be determined externally, was not breathing and its heart had stopped. A veterinarian attempted CPR before it was pronounced dead at 10:28 a.m.

"This is devastating for all of us here," National Zoo director Dennis Kelly said at a news conference. "It's hard to describe how much passion and energy and thought and care has gone into this."

Four American zoos have pandas, but Washington's pandas are treated like royalty. The zoo was given its first set of pandas in 1972 as a gift from China to commemorate President Richard Nixon's historic visit to the country.

Mei Xiang's first cub, Tai Shan, born in 2005, enjoyed enormous popularity before he was returned to China in 2010.

The new cub, born Sept. 16, had been a surprise at the zoo. Fourteen-year-old Mei Xiang had five failed pregnancies before giving birth.

Panda cubs are especially delicate and vulnerable to infection and other illness. The first weeks of life are critical for the cubs as mothers have to make sure they stay warm and get enough to eat.

Panda mothers are about 1,000 times heavier than their cubs, and sometimes they accidentally crush them. On any given day in the first two weeks of life, cubs have a mortality rate of 17 to 18 percent, zoo officials said.

A necropsy was being conducted to determine the cause of death, and preliminary findings were expected Monday, said Suzan Murray, the zoo's chief veterinarian. The cub showed no external signs of trauma, she said.

"The cub was just beautiful. Beautiful little body, beautiful face, with markings just beginning to show around the eye," Murray said.

As they did after Tai Shan was born, keepers had been leaving Mei Xiang alone with her offspring, monitoring her on video feeds that were also streamed on the zoo's website. Mei Xiang was resting comfortably after the cub's death, officials said.

The zoo's first panda couple, Ling Ling and Hsing Hsing, had five cubs during the 1980s, but none lived more than a few days. One of the cubs was stillborn; two others died of pneumonia within a day; another died from lack of oxygen after birth; and the final cub died of an infection after four days.

Atlanta has had three cubs, and the San Diego zoo has had six, including a cub born this year. A panda couple in Memphis has yet to have a cub, despite several tries.

The cub had not yet been named in accordance with Chinese tradition — it was to receive a name after 100 days on Dec. 24. Had the cub survived until then, it would have been roughly the size of a loaf of bread and weighed around 10 pounds. It will not be named posthumously, Kelly said.

Kelly said it was too soon to know if the zoo would attempt to breed Mei Xiang again. She was artificially inseminated with sperm from the zoo's male panda, Tian Tian.

"These bears are so critically endangered that every panda cub is important," Kelly said.

The panda exhibit was closed indefinitely. Early Sunday afternoon, there was still a sign outside the panda house announcing the cub's birth, and many visitors were unaware of the death.

At the zoo's panda-themed gift shop, Diana Salguero, 24, of Manassas, Va., was trying on a headband with panda ears when she learned from a reporter about the cub's death.

"I want to cry right now," she said. "I'm heartbroken. I've been excited all week. That's why I came out today."