Cranes are large, long-legged and long-necked birds.  Unlike the similar-looking but unrelated herons, cranes fly with necks outstretched, not pulled back. Most have elaborate and noisy courting displays or "dances". While folklore often states that cranes mate for life, recent scientific research indicates that these birds do change mates over the course of their (considerable) lifetimes (Hayes 2005). Some species and/or populations of cranes migrate over long distances, while some do not migrate at all. Cranes are gregarious, forming large flocks where their numbers are sufficient.