With early spring temperatures rising, the Fenglin National Nature Reserve in Heilongjiang province recently welcomed increasing numbers of migratory birds coming back from the South.

Staff members in the reserve monitored migratory birds including scaly-sided mergansers, mandarin ducks, waxwings and mallard ducks.

To provide a comfortable living and breeding environment for birds, 20 nests for scaly-sided mergansers and mandarin ducks had been installed in the reserve in early March.

In addition, far-infrared cameras were installed near the nests to monitor the living habits of the birds and keep precious video data.

"We welcomed the first couple of scaly-sided mergansers on March 25, nearly one month earlier than previous years," said Wang Quanbo, a staff member from the reserve.

The scaly-sided merganser, also known as the Chinese merganser, is under first-grade national protection and classified as "endangered" on the International Union for Conservation of Nature's Red List.

In the reserve, there are more than 220 species of wild birds and 747 kinds of wild animals.