With a camera snapping photos of migratory birds, Liu Guanghui starts his daily patrol in the Caohai National Nature Reserve in Guizhou province.

The 54-year-old is vice-captain of the team patrolling Caohai Lake, a primary wetland area in the Yi, Hui, and Miao autonomous county of Weining. It is one of the largest wintering locations for black-necked cranes, a species under first-class national protection.

"The priority of our current work is to dynamically record the populations of the migratory birds and observe their activities to help them overwinter," say Liu, who has been patrolling the area for more than three decades.

Every mid-November, hordes of migratory birds fly to Caohai reserve to spend winter. "This is a ruddy shelduck, and that is a bar-headed goose," says Liu, pointing at the birds.

Liu is also a shutterbug who loves taking photos of migratory birds, which, in his eyes, is an objective way to record the changing bird species in the area.

"The majority of migratory birds are vigilant, so I take the snapshots quickly," says Liu. Sometimes, it takes several days at a time to keep watch on them during harsh winters in order to capture their natural and unique habits.

Feb 2 marked World Wetlands Day. Over the years, China has stepped up efforts in ecological conservation, with significant progress made in protecting and expanding wetlands through the construction of national parks, the restoration of shrinking wetlands and other measures.

Over the years, the populations and types of wintering rare bird species in Caohai reserve have increased. This year it has welcomed oriental white storks, an endangered bird species.

The reserve is home to over 100,000 wintering migratory birds, including gray cranes, bar-headed geese, and black-necked cranes, among other species. The number of wintering black-necked cranes has reached 2,588.

This season's cold weather has caused foraging trouble for the wintering birds. To ensure these birds have ample food, on Jan 15, the reserve's management committee launched a feeding program.

"Over 1,000 kilograms of grain is provided per day, and the feeding will continue until mid-March," says a staffer with the management committee.

The wintering migratory birds have flocked to Caohai reserve, thanks to the efforts of Guizhou's governments at various levels in local ecosystem restoration.

Since a plan for Caohai's ecological protection and comprehensive treatment was approved in November 2015, 4,000 hectares of cultivated land have reverted to wetland, according to data from the management committee.

At present, the area of Caohai reserve has been restored to 120 square kilometers. The number of migratory bird species and biological species has increased from 220 and 1,954, respectively, in 2016 to 246 and 2,600 today.