A weather vane is a device that is used to indicate the direction of wind. Weather vanes may be functional or decorative. They are normally placed on the top of buildings and commonly have a cockerel design. It is also known as wind vane and sometimes as weathercock when it comes with a cockerel or rooster design. Weather vanes were common in America and were used by the farmers to predict the direction of wind. Antique weather vanes are popular collectibles.