The birds were put under observation for 24 hours, and then Cui began to feed them egg yolks and glucose powder using a small syringe.

"Four days later, the birds could be fed small live fish and shrimp," he said. "We also had to pay a lot of attention to their health by monitoring their weight."

The weight of the Chinese merganser had climbed from about 75 grams when it was born to more than 800 grams when it was released at the river, Cui said.

"As far as I know, there had been no successful artificial incubation of the Chinese merganser in the Changbai Mountain region or even across the country," he said. "Now we have gained more experience with artificial incubation and are fully prepared for such situations in the future, which also provides hope for the survival of these abandoned duck eggs."

Located in the Changbai Mountain Nature Reserve, the Toudao River is one of the most important habitats for the mergansers.

"Every year around March 10, a group of Chinese mergansers migrate from the southern regions to the river to reproduce," said Luan Jian, a staff member at the management center. "We have placed great emphasis on employing a series of methods to provide the birds with a more comfortable habitat, including building artificial bird nests, adding new fish fry and increasing daily monitoring.

"Data shows that this year, 16 pairs of Chinese mergansers have built their nests in the Toudao River area, and 140 eggs have been incubated," he added.