Giant pandas in parts of southern China are facing food shortages because a favourite staple - arrow bamboo - is blossoming and therefore inedible.
The pandas will probably be forced to adapt to other foodstuffs
The official Xinhua news agency said that the plant normally takes a decade to complete the blossoming process.
The agency said it left 19 pandas at the Piankou Nature Reserve in south-west China at risk.
It quoted Li Zuobin, a wildlife specialist in the region, as saying the situation was "very serious".
"Giant pandas in serious condition will be rushed to two neighbouring giant panda research and breeding areas," he was quoted as saying.
Zhang Heping, director of another panda reserve in south-western China - Wolong Nature Reserve - said that while the strong pandas will probably survive, the weaker ones may die.
China earlier this year announced the results of a first comprehensive survey of its wild panda population.
This showed there were an estimated 1,600 of the creatures left in the wild, 40% more than previous figures suggested.
Correspondents warned that the numbers might reflect the fact that the survey was so thorough, rather than a genuine recovery in numbers.
A further 161 pandas were reported to be living in captivity.