Desert oasis a lifeline for migratory birds

'Bird airport'

The wetlands are sometimes described by locals as a "bird airport".

Wetland ranger Jiang Yonghong sees this seasonal traffic firsthand as he patrols the Zhengyi Gorge area in Gaotai, a natural breeding ground for black storks.

Zhangye sits on the edge of the vast Badain Jaran Desert, the third-largest desert in China, covering about 49,200 square kilometers. The desert stretches across much of the landscape to the north and west, while the Qilian Mountains rise to its south. The Heihe River cuts through this dry landscape, creating wetlands where migratory birds can stop, feed and rest.

The Zhangye Heihe Wetland National Nature Reserve includes natural habitats such as the Heihe River and its tributaries and marshes, as well as man-made reservoirs and artificial lakes, said Shan Guofeng, head of the reserve's animal and plant protection department. The diverse habitats support 246 bird species, including 107 waterbird species, along with nationally protected wildlife.

Located along key sections of the Central Asian-India flyway and the East Asian-Australasian flyway, Gansu serves as an important stopover for hundreds of thousands of migratory birds.

Large numbers of migratory birds arrive from early September, with the number peaking around mid-October, Jiang said. Black storks are one of the main species, while other waterbirds use reservoirs, shallow waters and mudflats.

Jiang compares the wetlands to a highway service area.

After flying hundreds or even thousands of kilometers, birds need somewhere to stop, rest and feed, he said. "They may have found this oasis and chosen to stop here," said Shan.

The wetlands are not simply a place for birds to pass through. For black storks, they also provide a breeding ground.

Known as the "giant panda of birds", the black stork is demanding when it comes to its habitat requirements. It needs clean water, sufficient food and minimal human disturbance to breed and survive. For this reason, the species is often seen as a natural indicator of an ecosystem's health.

Black storks often choose the cliffs around Zhengyi Gorge for breeding because they are high and relatively isolated, Jiang said. Their proximity to the wetlands also allows them to forage for fish and shrimp and carry food back to their nests.

The breeding season typically begins in late March or early April. Chicks generally hatch around May and begin leaving the nest in late July or early August.

During the breeding period, conservation workers place warning signs and fences around some nests and, when necessary, place small fish and shrimp in the river to supplement natural food sources.