White swans are seen on the Ulunggur Lake in Fuhai County of Altay Prefecture, northwest China's Xinjiang Uygur Autonomous Region, April 6, 2014. (Xinhua/Liu Xinhai)

White swans are seen on the Ulunggur Lake in Fuhai County of Altay Prefecture, northwest China's Xinjiang Uygur Autonomous Region, April 6, 2014. (Xinhua/Liu Xinhai)

White swans are seen on the Ulunggur Lake in Fuhai County of Altay Prefecture, northwest China's Xinjiang Uygur Autonomous Region, April 6, 2014. (Xinhua/Liu Xinhai)

White swans are seen on the Ulunggur Lake in Fuhai County of Altay Prefecture, northwest China's Xinjiang Uygur Autonomous Region, April 6, 2014. (Xinhua/Liu Xinhai)

White swans are seen on the Ulunggur Lake in Fuhai County of Altay Prefecture, northwest China's Xinjiang Uygur Autonomous Region, April 6, 2014. (Xinhua/Liu Xinhai)

White swans are seen on the Ulunggur Lake in Fuhai County of Altay Prefecture, northwest China's Xinjiang Uygur Autonomous Region, April 6, 2014. (Xinhua/Liu Xinhai)