KUNMING -- A white-bellied heron, also called Ardea insignis, a critically endangered bird species, was spotted and rescued in Southwest China's Yunnan province, local authorities said Saturday.

The physically exhausted bird was found in Changning county by a local villager on Nov 10, and transferred to the Wildlife Shelter and Rescue Center of Baoshan City for feeding and nursing after identification.

"The bird has been identified as a white-bellied heron," said Han Lianxian, an ornithologist and professor at Southwest Forestry University, adding that the bird is a large heron unique to the southern slopes of the Himalayas, and listed as critically endangered by the International Union for Conservation of Nature.

"The bird may be a newborn and suffered from physical exhaustion as it strayed from its natural habitat," Han said.

The researchers conducted a two-day assessment of the bird's physical condition and whether it was fit for release. The bird was released from a vast river valley in Changning on Friday, after experts determined that it had regained its physical fitness and was able to survive in the wild.

"The scarcity of white-bellied herons is closely related to their stringent habitat requirements, making them an indicator species of river ecology," Han said.

Researchers have installed a satellite tracking recorder on the white-bellied heron's back and put on an ankle ring to monitor it and develop rescue measures.