TIANJIN -- More than 5,000 oriental white storks have been spotted in North China's Tianjin municipality since October, accounting for around half of the species' total global population, local authorities said Wednesday.

As Tianjin's ecological environment improves, greater numbers of migratory birds are flocking to the area, making use of its managed wetlands, with 100,000 birds of various species arriving since the start of autumn this year, according to Lu Hong, an official with the planning and natural resources bureau of Tianjin.

To ensure that the migratory birds cross the city safely and survive the winter, the major wetland reserves, including Tianjin Beidagang and Qilihai, have taken timely measures, said Lu Hong.

Through the regulation of water levels at the Qilihai wetland, shoals and swamps have been formed over an area of 1,300 hectares. Perches have also been built on which birds can nest and reproduce.

On Nov 9, the Beidagang wetland released more than five tonnes of fish fry to meet the increasing demand from birds.

The oriental white stork, a migratory bird species under first-class national protection, is listed as "endangered" by the International Union for Conservation of Nature. Its global population has reached 9,000, according to the latest statistics from the joint crane conservation committee of China Wildlife Conservation Association.