During the early days of spring at the end of March, when temperatures were still low, photographer Sun Qianglie had his tent set up on the bank of the Hailang River in Heilongjiang province.

Over the years, Sun, a 65-year-old retiree who worked at the Dahailin Forestry Bureau of the State-owned China Longjiang Forest Industry Group, has taken numerous photos of Chinese mergansers at the river and has witnessed the increase of the rare birds in the region.

Listed as a national first-class protected animal and classified as endangered on the International Union for Conservation of Nature's Red List, Chinese mergansers have been dubbed "living fossils".

"By chance, while taking pictures near the river in the spring of 2014, I found a group of white ducks," he said. "After doing some research and confirming with the local resource management department, I learned that they were rare Chinese mergansers, but at that time, there were very few."

After retiring in 2019, Sun began devoting himself to photographing Chinese mergansers.

To that end, he has consulted a large number of books and information to understand the habits of Chinese mergansers and has often spent entire days waiting in areas where the birds were active on the banks of the Hailang.

Starting from April 1, 2014, the China Longjiang Forest Industry Group banned commercial logging to contribute to the nation's green development efforts.

"Since then, the ecological environment in our forest area has improved, and the number of Chinese mergansers has increased year by year," Sun said.

The retiree admits that the quality of his photos isn't always as good as he would like, but he said that he feels fortunate that he's been able to observe the rare birds in person, and that he's been able to promote his hometown with the pictures.

"I hope my photos can encourage more people to learn about the environment of the forest and how it has greatly improved, attracting more wild animals," he said.

With the continuous improvement of the environment in recent years, areas of the forest managed by the Longjiang group have become an ideal habitat for numerous migratory birds.

These areas have welcomed large groups of returning migratory birds, including white-headed cranes, Chinese mergansers, herons and wild geese.

The birds have been seen flocking together and chasing each other in the sky, or circling and landing to rest and search for food along the rivers, creating a unique scene as spring unfolds.

"As early as the end of March, even before the snow melted, migratory birds had already returned," said Gu Yanchang, a staff member from Dazhanhe National Wetland Nature Reserve under the Zhanhe Forestry Bureau in the province. "To create a comfortable, peaceful habitat for migratory birds, in addition to our daily patrols and monitoring, we have also provided some food for them in their activity areas.

"The biodiversity here has been steadily increasing, and more bird species have come to the reserve," he said. "So far, we have monitored 103 species of birds, with more than 240,000 bird sightings."