A growing number of black-necked cranes have returned to a nature reserve in southwest China's Guizhou Province to spend the winter, thanks to the ongoing ecological protection efforts.

The Caohai National Nature Reserve in Guizhou had recorded more than 2,400 overwinter black-necked cranes as of Monday, with the number steadily increasing compared to the same period in previous years, according to the reserve's management committee.

Meanwhile, this migration transfer station had also observed about 34,000 other birds, including grey cranes, bar-headed geese, and bone-headed chickens.

To ensure the safe wintering of migratory birds, the reserve has established a grid-based patrol system to conduct safety inspections and supervision throughout the area.

"I'm in charge of the largest among the seven nocturnal habitats, which is also the site with the largest number of black-necked cranes. During the same period last year, there were about 800 black-necked cranes. This year, the number has increased to around 1,100," said Ma Mindian, a ranger.

The significant growth in the population of endangered birds such as black-necked cranes is attributed to the reserve's continuous efforts to protect the wetland ecosystem. Caohai currently hosts 252 bird species.