For the past six consecutive years, Pinglu has compensated local farmers 400,000 yuan ($57,100) annually to return farmland to wetland.

Pinglu strives to find a "balance point" between the ecological and economic benefits. The county is constructing a swan ecological economic demonstration zone with an investment of 3 billion yuan. After the completion of its first stage, it is expected to receive more than 500,000 tourists a year.

The rise of the "swan economy" has strengthened the awareness of authorities and people across China of the need to protect the species and the ecological environment.

In 2014, Sanmenxia has designated Nov 22 as "Swans Protection Day".

Last winter, an international academic exchange conference on swan conservation was held in the city of Rongcheng in East China's Shandong province, another important swan migration site.

Representatives and scholars from China, Russia and Japan, among other countries, jointly issued the Rongcheng Declaration on Swans Conservation, aimed at strengthening international cooperation in the protection of the birds.

Guo Lixin, deputy secretary-general of the China Wildlife Conservation Association, said at the meeting that Rongcheng's swan protection and management model based on community participation has formed an urban ecology in which people and nature harmoniously coexist.

In 2013, China set a "red line" of no less than 53 million hectares of wetlands by 2020. In 2019, 158 pilot national wetland parks in China passed appraisal, according to the National Forestry and Grassland Administration.

Thanks to the introduction of multiple protection policies and increasing financial investment, China's continuous improvement of the ecological environment has become the best "escort" for the migration of swans.

"As China continues to improve its ecological environment, there may be more swans flying from Siberia to spend the winter in China," Zhang says.