SHIJIAZHUANG, April 9 (Xinhua) -- Thousands of migratory birds have made stopovers in a national wetland park in north China's Hebei Province as they flock north.

The Shandianhe National Wetland Park, in the county of Guyuan, has seen more than 5,000 migratory birds, the biggest number in recent years, according to the park staff.

Some of the birds have tags around their feet, and a bird expert said the birds come from Mongolia.

"They fly to Poyang Lake every year to get through the winter and go back when the temperature rises in the north," said Guo Yuming, a professor with Beijing Forestry University.

The Shandianhe National Wetland Park covers an area of about 4,120 hectares and consists of rivers, lakes, intertidal zones and artificial ponds.

As the environment keeps improving in the wetland and food abounds, more migratory birds rest there during migration.