With the onset of winter, migratory birds flock to the Napa Lake Wetland in Shangri-La, southwest China's Yunnan province to seek warmth there.

Over 200 black storks, recognizable by their black plumage, white underparts, long red legs, and pointed red beaks,have been spotted foraging in the muddy silt around the lake, feasting on their favorite fishes, frogs, and crustacean shellfish.

"This indicates that the food supply in this place is sufficient, so these black storks can forage here. Some of them will stay here for a while before they continue to head south with fully replenishing, while more than 100 of them will stay at the Napa Lake for the whole winter," said Chen Zhiming, senior engineer at the administration of Napa Lake provincial nature reserve.

With more and more black storks and other migratory birds coming, Chen and his colleagues have ramped up their daily patrols and inspections.

Recent observations show a growing influx of migratory birds at the Napa Lake for wintering, with black-necked cranes (Grus nigricollis) numbering over 400.

The migratory birds arrive in mid-October and leave from late March to mid-April. In the last wintering season, a record high of 510 black-necked cranes were recorded, indicating a positive trend in the habitat's condition.

Black-necked cranes, black storks, and white-tailed eagles are all under the top-class state protection. Apart from them, other migratory birds like Eastern spot-billed ducks and bar-headed geese have also come to the Napa Lake in succession.

"Forest birds around the Napa Lake and water birds in the lake have counted more than 200 species, and numbered over 50,000 at the peak of the wintering season. This indicates that the environment of the Napa Lake has changed, with sufficient food and a safe ecology for the wintering birds," said Chen.