The great blue windrunner is a large bird with a wingspan of 3 meters (about 10 feet). This bird inhabits the mountainous Great Plateau during the warmer months. Its ancestors were cranes. The Great Plateau is much higher than the former Tibetan Plateau, so the windrunner had to adapt to cope with the thin air. These birds are able to reach high altitudes but the thin air cannot support wings as well as denser air near the ground, and the windrunner must also be able to spend its winters in the lowlands. To solve the problem, the windrunner evolved flight feathers on its legs, so it can use them as an extra pair of wings for gliding by spreading them out to the sides in midflight, like the prehistoric Microraptor. Its head also has feathery tufts which act as gliding wings to support its head in flight. At such high altitude, more ultraviolet light from the sun leaks through the atmosphere. The windrunner is covered in fluorescent blue feathers that reflect this ultraviolet light. Windrunners can also see in ultraviolet and so use the light to recognize one another. Their eyes are protected from this otherwise dangerous light by lenses which act as "built-in sunglasses". The great blue windrunners primarily eat silver spiders snatched from their webs. During early summer months the birds gather together to mate. The males will perform a dance that will attract a female. When the eggs hatch their parents take care of their young for 3 months.