KUNMING, Oct. 15 (Xinhua) -- An endangered bird, one of the most elusive members of the heron family, was again recently spotted in mountains in southwest China, nature reserve officials told Xinhua on Tuesday.

The white-eared night-heron, indigenous to China and Vietnam, has now been seen in this reserve for four consecutive years, said Li Xingzhi, an official with the Ailao Mountains nature reserve in Yunnan Province.

The species is listed as endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. It also enjoys top-level protection from the Chinese government.

Li noted that a spotted adult bird weighing 594 grams and measuring 63.2 cm in length was recently captured in the reserve by a team of experts.

"Bird calls could be heard nearby that night, indicating the presence of more than one such bird," said Zhao Xuebing, a PhD student from Yunnan University, who participated in a bird-banding operation which was taking place when the sighting happened.

The captured heron has since been released back into the wild, equipped with a satellite tracker to monitor its movements.

The Ailao Mountains are rich in biodiversity, serving as home to 86 mammal species and 323 bird species -- including the western black-crested gibbon, clouded leopard and green peafowl.

Currently, authorities have only opened the outer areas of the Ailao Mountains to tourists, as much of the inner area remains a vast, untouched forest with potentially dangerous terrain. The region has gained popularity on Chinese social media platforms, with content creators regularly sharing thrilling videos of their experience in and around the reserve.