On hot summer days, flocks of birds either paddle on the tranquil waters or perch among the lush reeds at Nandagang wetland in Cangzhou city, North China's Hebei province.
SHIJIAZHUANG, June 30 (Xinhua) On hot summer days, flocks of birds either paddle on the tranquil waters or perch among the lush reeds at Nandagang wetland in