LANZHOU - Four snow leopards were spotted by an infrared camera in Northwest China's Gansu province, according to local authorities Friday.

The leopard family was wading across a river. The mother held one cub in her mouth, while another cub made its way without mother's help.

Yanchiwan Nature Reserve said they set up 86 infrared cameras in May this year, and found that 53 of the cameras had recorded images of snow leopards over 341 shots.

In the past five years, a total of 3,105 photos and 515 pieces of video footage of snow leopards have been taken at the reserve.

Dou Zhigang, head of the reserve management bureau, told Xinhua that snow leopards had a good sense of smell, so it was hard for researchers to catch sight of them.

The nature reserve covers an area of 1.36 million hectares. In recent years grazing was banned or controlled in the area, and the population of wild animals has grown.

Snow leopards are a Class A protected animal in China. They live in the Himalayas in central and south Asia at an altitude of 2,500 to 4,500 meters. They have been spotted in China's provinces of Gansu, Qinghai, Sichuan and Yunnan, and autonomous regions of Tibet and Xinjiang.

The animal has rarely been seen in the wild this century due to loss of habitat and poaching. There are an estimated 3,500 to 7,000 snow leopards living in the wild in addition to around 650 in captivity worldwide, according to official figures released in 2015.