The crossword solution for the term 'Bird on a Weather Vane' is 'ROOSTER', which is a seven-letter word. A ROOSTER is a male chicken, and it is often seen perched atop a weather vane. Roosters are known for their loud crowing, which is used to announce the start of the day. Weather vanes are used to indicate the direction of the wind, and having a ROOSTER perched atop one is a common sight in many parts of the world.