In March of early spring, when winter snow has not yet melted in Tanghe Wetland in Liaoyang County, Liaoyang City, Liaoning Province, flocks of slim and beautiful grey herons come into sight. These birds, either flap their wings to soar or seek for food in the water, adding much vitality to spring here. From March to August every year, they come to Tanghe Wetland for food and breed before migrating to wintering ground all over the world. With its population growing from few hundreds to more than 1000 now, grey heron has become an iconic bird in Tanghe Wetland.