White swans frolic by the waterside at the Sanmenxia Swan Lake National Urban Wetland Park, Oct. 23, 2018. The Yellow River wetland in Sanmenxia, covering an area of 28,500 hectares, accounts for around 42 percent of the total area of the Henan Yellow River Wetland National Nature Reserve. Till Oct. 26 this year, over 500 white swans have migrated there to spend the upcoming winter. (Photo/Asianewsphoto)
White swans frolic by the waterside at the Sanmenxia Swan Lake National Urban Wetland Park, Oct. 23, 2018. The Yellow River wetland in Sanmenxia, covering an area of 28,500 hectares, accounts for around 42 percent of the total area of the Henan Yellow River Wetland National Nature Reserve. Till Oct. 26 this year, over 500 white swans have migrated there to spend the upcoming winter. (Photo/Asianewsphoto)
White swans frolic by the waterside at the Sanmenxia Swan Lake National Urban Wetland Park, Oct. 23, 2018. The Yellow River wetland in Sanmenxia, covering an area of 28,500 hectares, accounts for around 42 percent of the total area of the Henan Yellow River Wetland National Nature Reserve. Till Oct. 26 this year, over 500 white swans have migrated there to spend the upcoming winter. (Photo/Asianewsphoto)
White swans frolic by the waterside at the Sanmenxia Swan Lake National Urban Wetland Park, Oct. 23, 2018. The Yellow River wetland in Sanmenxia, covering an area of 28,500 hectares, accounts for around 42 percent of the total area of the Henan Yellow River Wetland National Nature Reserve. Till Oct. 26 this year, over 500 white swans have migrated there to spend the upcoming winter. (Photo/Asianewsphoto)