HARBIN, March 29 (Xinhua) -- About 20 red-crowned cranes have been spotted in Zhenbao Island, a wetland reserve in the northeastern province of Heilongjiang, the biggest group ever recorded in the area.

Red-crowned cranes are an endangered species mainly found in the northeast of China, Japan and Democratic People's Republic of Korea (DPRK).

On Tuesday, 18 cranes were found following a sighting of two on Monday, according to Han Zhaojiang, a worker at the reserve.

The birds were rarely seen in Zhenbao Island, Han said, adding that in 2017, only eight were spotted at the reserve.

Covering about 29,000 hectares, Zhenbao Island wetland has been included on the Ramsar List of Wetlands of International Importance.