In the Zhalong wetland in Heilongjiang province, one of the world's largest breeding and nesting sites for red-crowned cranes, dedicated caretakers have been working for years to nurture and monitor the birds and build up the wild crane population.

Xu Hui, a caretaker at the Zhalong National Nature Reserve, has been working as a bird keeper for 17 years and is responsible for feeding and monitoring cranes released into the wild.

He and his team members use telescopes or get closer when necessary to check on crane eggs.

"For the 33 days of incubation, we observe their situation without disturbing them," he said.

"The monitoring is necessary because if adult birds sense any danger, they will run away, abandoning their babies."

Since the reserve was set up in 1979, caretakers have been training the cranes in survival skills before releasing them into the wild.

Today, nearly 300 wild red-crowned cranes live in the Zhalong wetland, with more than 1,000 artificially bred ones at the reserve, the provincial government said. In 1979, the population was just 150.

Each autumn, the wild cranes migrate from Zhalong to the Yellow River Estuary in Shandong province and Yancheng in Jiangsu province, for the winter.

"It is not possible to release all the cranes into the wild at once," Xu said. "We need to ensure there's enough habitats and food in the wild. Otherwise, they will have difficulty adapting."

The reserve aims to restore and maintain the habitat area, focusing on wetland water supplementation, reed preservation and relocation of people, the local government said.

The Zhalong wetland has been facing the threat of water depletion due to an increase in the local population and human activities.

In response, the reserve established a long-term wetland water supplementation system in 2009 that has replenished more than 3 billion cubic meters of water so far, with the wetland area maintained at more than 170,000 hectares.

The preservation of reeds is also crucial for the habitat of the rare cranes.

"The locals in the area used to fish and harvest reeds for their livelihood, inevitably affecting the environment," Xu said. "Reeds were cut for making crafts and paper."

Wang Tao, Party chief of Qiqihar city's Halawusu village committee and a deputy to the local people's congress, where the people were relocated to, said: "After the relocation, the wetlands were restored to a better state. It became more suitable for natural habitats to thrive."

Some of relocated people now do sanitation work, Wang said, while some work in tourism-related industries.

China's first specialized law on wetland protection made by the National People's Congress came into effect last year, making the division of management responsibilities clearer and punishment for damaging behavior more severe.

The law restricts construction projects in important national wetlands and bans all harmful behavior, including overgrazing, overharvesting, the discharge of wastewater and land reclamation.

The conservation efforts in the Zhalong wetland are part of a broader initiative in Heilongjiang.

Since the 1990s, the province has been committed to wetland protection.

Today, the province boasts 12 internationally important wetlands, the highest number in the country.

lihongyang@chinadaily.com.cn