A flock of bean geese fly above the Dongting lake in Hunan province, Mar 1, 2017. Many birds gather together near the Dongting lake district as they prepare to fly north. Each October, a significant number of migratory birds fly from the northern part of China to the Dongting lake to spend the harsh winter. A survey conducted in January this year showed that there were more than 180,000 migratory water birds in the region, which is the highest since 2006.[Photo/Xinhua]