Aerial photo shows trees in the Yellow River's wetlands becoming a gathering place for grey herons in Haidong City, northwest China's Qinghai Province. As temperatures gradually rise, a group of special "guests", grey herons, have arrived along the Yellow River, adding a beautiful ecological touch to the early spring landscape. (Photo: China News Service)

Grey herons build a nest with its partners in Haidong City, northwest China's Qinghai Province. (Photo: China News Service)

Grey herons build their new homes in the riverside forests in Haidong City, northwest China's Qinghai Province. (Photo: China News Service)

A grey heron rests on the branches in Haidong City, northwest China's Qinghai Province. (Photo: China News Service)