The body of Xiang Xiang, a five-year-old male panda, was discovered on snow-covered ground in the bamboo forests of Sichuan Province on February 19. The news was held until experts could conduct a full examination.
The panda appears to have died from injuries it sustained in a fall after getting into a fight with wild-born males.
Released last April, Xiang Xiang was the first and only giant panda to be set free since captive breeding of the rare animals began more than 40 years ago.
Conservationists had hoped that the pioneer panda would mark the start of a successful program to reintroduce the endangered mammals in their native habitat.
The examination of Xiang Xiang's body revealed that the panda had suffered broken ribs and serious internal damage, according to staff at the Research and Conservation Center for the Giant Panda at Wolong Nature Reserve in China.
"Scratches and other minor injuries caused by other wild pandas were found on his body," the center's Heng Yi told the Associated Press.
"Xiang Xiang may have fallen from trees when being chased by those pandas."
The 176-pound (80-kilogram) male was reared at the Wolong center, where he was trained for a new life in the wild from the age of two.
Xiang Xiang, whose name means "lucky" or "auspicious," had been fitted with a collar carrying a satellite tracking device.
Researchers last picked up signals from the device 40 days before the panda was found dead, according to reports.
In December Xiang Xiang had been discovered suffering from injuries, including bite marks to his back and shoulders. He was taken back to the Wolong center for treatment before being re-released.
Marc Brody, a panda conservationist and National Geographic Society Conservation Trust grantee, said the area where Xiang Xiang was released is already well populated by pandas.
"Males have their territory and they are likely to defend it fiercely," he added.
A panda's range is typically 1.5 to 2 square miles (4 to 5 square kilometers). But radio tracking of Xiang Xiang indicated that he had been roaming over a much greater area.
Researchers believe that other males were keeping the panda on the move by chasing him away from their patches, Brody said.
"He was trying to find a spot to call his own, but he was unsuccessful in doing so," Brody said.
Brody is the founder of the U.S.-China Environmental Fund, which is working with Chinese researchers to conserve wild pandas and their habitat.
Xiang Xiang's death, he said, is a setback to efforts to reintroduce pandas to the wild. But researchers at Wolong intend to continue with the program.
"There are preparations to have two more pandas go through wild training for reintroduction," Brody added. "No dates for the releases of those pandas have yet been given."
In the future, Brody said, it's hoped that captive-bred pandas can be used to repopulate areas where wild pandas currently survive in low numbers or are absent.
Brody emphasized that the key is to place greater effort on habitat restoration and conservation. He also said he encourages efforts to help Wolong personnel identify areas suitable for reintroducing captive-bred animals.
The Wolong project, for example, includes surveys to identify degraded forest areas that could be restored, providing potential new panda habitat.
Only about 1,600 giant pandas are still left in the wild, conservationists say.