I would like to bring to your attention the horror that is 'roller' pigeons.
These pigeons are bred specifically for their ability to 'roll' backwards on the floor. This is caused by a genetic defect resulting in spasmodic movements and an inability to fly.
Another breed is able to fly, doing backwards somersaults in the air. These birds frequently crash land, resulting in death.
I believe these birds should be banned, breeding them is like breeding humans for epilepsy. These birds are deprived of flight, the very essence of being a bird.
The following video shows a 'roller' pigeon in action:http://www.youtube.com/watch?v=jxQeTq-FmVA