Black-winged Stilt (Himantopus himantopus, 黑翅长脚鹬).
They range all over Africa, Europe and Asia, but they are infrequent visitors to Changsha; sometimes they venture into the small lakes, sometimes they feed in the shallow parts of the Xiang river, most likely on small crustaceans but I have not observed this closely. Individuals vary in black and white colouration. Their pink legs stand out anywhere but in the right light, and right angle they easily blend into the shimmering water.
