Patrollers have made the first discovery of Mute Swans breeding in the Yellow River Delta National Nature Reserve in Dongying, Shandong province, this summer, with a pair of adult Mute Swans playing and foraging with their six cygnets captured.

The swan family was initially found in June. The cygnets are now over two months old, nearly the size of adult swans, and are seen to be growing healthily.

Experts said that the Mute Swan is a second-class nationally protected species in China and is relatively rare. They typically breed in regions, such as Xinjiang and Inner Mongolia autonomous regions, and Qinghai, Gansu provinces. Their migration routes could pass through Shandong province, before heading south for the winter.

In July, the bird habitat at the Yellow River Estuary in Dongying, Shandong, was listed as a World Natural Heritage site as part of the Migratory Bird Sanctuaries along the Coast of the Yellow Sea-Bohai Gulf of China (Phase II).

This area is a crucial stopover, wintering, and breeding site for migratory birds in the East Asian-Australasian Flyway, earning the nickname "International Airport for Birds" from experts both domestic and international.

With the improvement of the ecological environment, the number of bird species living in the Yellow River Delta National Nature Reserve has doubled over the past 30 years, increasing from 187 species to the current 373 species.

Yang Bin contributed to this story.