Avian guardian: What are the 'migratory bird restaurants' in E China?

Poyang Lake is located in east China's Jiangxi Province. Situated at the convergence of three migratory bird routes and recognized as China's largest freshwater lake, it has welcomed over 700,000 migratory birds for wintering since the onset of the current winter.

The Siberian crane, a flagship species among the wintering birds in the wetlands of Poyang Lake, is a first-class state-protected bird in China. The International Union for Conservation of Nature lists the Siberian crane as critically endangered, with a global population estimate of merely 3,500 to 4,000 disclosed in previous years.

Yu Changhao, director of the Wetland and Grassland Management department at the Forestry Bureau of Jiangxi Province, remarked, "In the past two to three years, there has been a noticeable change in the Siberian crane population that migrated to the Poyang Lake. The numbers departing from breeding grounds have already increased. Additionally, they have passed through many newly-established protected areas along their migration routes which allow them to take a break and feed. Consequently, the number of deaths during the migration has decreased, leading to a rise in the annual arrivals to the Poyang Lake area."

According to China's latest survey in 2022, the Siberian crane population has surged to over 5,600. Simultaneously, populations of other rare bird species like the white-naped crane and oriental white stork have also notably increased. However, with the burgeoning bird populations, ensuring an adequate food supply has emerged as a new challenge.

Yu said that with the continuous increase in population, the adequacy of food supply in Poyang Lake for these birds has become a pressing issue. The dietary preferences among migratory birds also vary significantly: some are piscivorous, feeding on fish and shrimp; others are herbivorous, consuming grasses, while some subsist on underground plant roots.

In recent years, drastic changes in climate, like extreme weather, have significantly altered the hydrology of Poyang Lake, impacting vegetation growth patterns in the lake area. To ensure food resources for wintering birds like wild ducks and swans, which feed on tender leaves, roots, and seeds, the region initiated cutting aging grasses starting in late September this year.

Vallisneria spinulosa, a common species in the Poyang Lake area, provides winter buds as a primary food source for some migratory birds. However, its growth has been heavily affected by hydrological changes. Due to insufficient natural food sources during certain years affected by climate change, many migratory birds shift from the lake's wetlands to nearby farmlands for foraging.

In recent years, relative departments have established numerous "bird restaurants" around Poyang Lake, reserving portions of agricultural production in farmland and ponds as supplementary food for wintering birds. Additionally, ecological compensation funds have been provided to local farmers.