What is a "spur"?

A spur is a bony projection found on the legs or wings of certain birds, particularly in roosters and some species of birds of prey. It is a specialized structure that serves various purposes depending on the species. In roosters, spurs are located on the lower leg and are used as a weapon during territorial disputes or when defending against predators. They can be sharp and pointed, capable of inflicting injury. In birds of prey, such as hawks and eagles, spurs are typically found on the wings and are used for gripping and maneuvering during flight.